From a14a7288cd1909c6df573d2fbe16374d32b701aa Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 26 Aug 2023 16:14:00 +0800
Subject: [PATCH 01/28] Update Duke.java

renamed chatbot from duke to Dom, added the various lines
---
 src/main/java/Duke.java | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 5d313334c..9a10124c3 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,10 +1,14 @@
 public class Duke {
     public static void main(String[] args) {
-        String logo = " ____        _        \n"
-                + "|  _ \\ _   _| | _____ \n"
-                + "| | | | | | | |/ / _ \\\n"
-                + "| |_| | |_| |   <  __/\n"
-                + "|____/ \\__,_|_|\\_\\___|\n";
+        String logo = "  ____                  \n"
+                + " |  _ \\  ___  _ __ ___  \n"
+                + " | | | |/ _ \\| '_ ` _ \\ \n"
+                + " | |_| | (_) | | | | | |\n"
+                + " |____/ \\___/|_| |_| |_|\n";
         System.out.println("Hello from\n" + logo);
+        System.out.println("Hello! I'm Dom");
+        System.out.println("What can I do for you?");
+
+        System.out.println(("Bye. Hope to see you again soon"));
     }
 }

From cbd58cc55444745d8955ed66a5e2693d7b5c767a Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sun, 27 Aug 2023 11:51:26 +0800
Subject: [PATCH 02/28] Level 0 increment, edited code

---
 src/main/java/Duke.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 9a10124c3..b18e9d794 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -6,7 +6,7 @@ public static void main(String[] args) {
                 + " | |_| | (_) | | | | | |\n"
                 + " |____/ \\___/|_| |_| |_|\n";
         System.out.println("Hello from\n" + logo);
-        System.out.println("Hello! I'm Dom");
+        System.out.println("Hello! I'm Dom!");
         System.out.println("What can I do for you?");
 
         System.out.println(("Bye. Hope to see you again soon"));

From b5b91a42ae50ff04f6d5eed2ab3639dfda848738 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Tue, 29 Aug 2023 22:33:26 +0800
Subject: [PATCH 03/28] Level 1

---
 .gitignore              |  1 +
 src/main/java/Duke.java | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/.gitignore b/.gitignore
index 2873e189e..09df8809c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,3 +15,4 @@ bin/
 
 /text-ui-test/ACTUAL.TXT
 text-ui-test/EXPECTED-UNIX.TXT
+*.class
diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index b18e9d794..bf3bc5105 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,3 +1,5 @@
+import java.util.Scanner;
+
 public class Duke {
     public static void main(String[] args) {
         String logo = "  ____                  \n"
@@ -8,7 +10,17 @@ public static void main(String[] args) {
         System.out.println("Hello from\n" + logo);
         System.out.println("Hello! I'm Dom!");
         System.out.println("What can I do for you?");
-
-        System.out.println(("Bye. Hope to see you again soon"));
+        Scanner in = new Scanner(System.in);
+        while (true) {
+            String command = in.nextLine();
+            System.out.println("____________________________________________________________");
+            System.out.println(" " + command);
+            System.out.println("____________________________________________________________");
+            if (command.equals("bye")) {
+                System.out.println(("Bye. Hope to see you again soon"));
+                break;
+            }
+        }
     }
 }
+

From 82224dd3bab19a73cee32c763c3a8f35d7f531dd Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 30 Aug 2023 01:29:51 +0800
Subject: [PATCH 04/28] Completed Level 2 increment and updated code

---
 src/main/java/Duke.java | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index bf3bc5105..64ecee416 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,4 +1,5 @@
 import java.util.Scanner;
+import java.util.ArrayList;
 
 public class Duke {
     public static void main(String[] args) {
@@ -10,17 +11,40 @@ public static void main(String[] args) {
         System.out.println("Hello from\n" + logo);
         System.out.println("Hello! I'm Dom!");
         System.out.println("What can I do for you?");
+
         Scanner in = new Scanner(System.in);
+        ArrayList<String> list = new ArrayList<>();
+
         while (true) {
             String command = in.nextLine();
             System.out.println("____________________________________________________________");
-            System.out.println(" " + command);
-            System.out.println("____________________________________________________________");
-            if (command.equals("bye")) {
-                System.out.println(("Bye. Hope to see you again soon"));
+            if(command.equalsIgnoreCase("bye")) {
+                System.out.println("Bye. Hope to see you again soon!");
                 break;
+            } else if (command.equalsIgnoreCase("list")) {
+                System.out.println(" " + getTaskList(list));
+            } else {
+                list.add(command);
+                System.out.println("added: " + command);
+            }
+            //System.out.println(" " + command);
+            System.out.println("____________________________________________________________");
+            //if (command.equals("bye")) {
+                //System.out.println(("Bye. Hope to see you again soon"));
+                //break;
+            }
+        }
+        private static String getTaskList(ArrayList<String>  list) {
+            StringBuilder task = new StringBuilder();
+            if(list.isEmpty()) {
+                task.append("There is no task in your list");
+            } else {
+                for(int i = 0; i < list.size(); i++) {
+                    task.append(i + 1).append(".").append(list.get(i)).append("\n");
+                }
             }
+            return task.toString();
         }
     }
-}
+
 

From 59939a70b9de1172d3acd701f4e667428d6a2b66 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 30 Aug 2023 21:59:00 +0800
Subject: [PATCH 05/28] Added Task.java file, imporved on level-2 code
 completed level-3

---
 src/main/java/Duke.java | 133 ++++++++++++++++++++++++++++++----------
 src/main/java/Task.java |  27 ++++++++
 2 files changed, 128 insertions(+), 32 deletions(-)
 create mode 100644 src/main/java/Task.java

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 64ecee416..38c54a7e1 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,49 +2,118 @@
 import java.util.ArrayList;
 
 public class Duke {
-    public static void main(String[] args) {
+    /*
+     * This method prints the greetings message when the user starts the program.
+     */
+    public static void greetings() {
         String logo = "  ____                  \n"
                 + " |  _ \\  ___  _ __ ___  \n"
                 + " | | | |/ _ \\| '_ ` _ \\ \n"
                 + " | |_| | (_) | | | | | |\n"
                 + " |____/ \\___/|_| |_| |_|\n";
         System.out.println("Hello from\n" + logo);
-        System.out.println("Hello! I'm Dom!");
-        System.out.println("What can I do for you?");
+        String greetings = "____________________________________________________________" + "\n" +
+                "Hello! I'm Dom" + "\n" +
+                "What can I do for you?" + "\n" +
+                "____________________________________________________________";
+        System.out.println(greetings);
+    }
+
+    /*
+     * This method prints the goodbye message when the user exits the program.
+     */
+    public static void goodbye() {
+        String goodbye = "____________________________________________________________" + "\n" +
+                "Bye. Hope to see you again soon!" + "\n" +
+                "____________________________________________________________";
+        System.out.println(goodbye);
+    }
 
-        Scanner in = new Scanner(System.in);
-        ArrayList<String> list = new ArrayList<>();
+    /*
+     * This method prints the input message.
+     */
+    public static void echo(String input) {
+        System.out.println(input);
+    };
 
-        while (true) {
-            String command = in.nextLine();
-            System.out.println("____________________________________________________________");
-            if(command.equalsIgnoreCase("bye")) {
-                System.out.println("Bye. Hope to see you again soon!");
-                break;
-            } else if (command.equalsIgnoreCase("list")) {
-                System.out.println(" " + getTaskList(list));
-            } else {
-                list.add(command);
-                System.out.println("added: " + command);
-            }
-            //System.out.println(" " + command);
-            System.out.println("____________________________________________________________");
-            //if (command.equals("bye")) {
-                //System.out.println(("Bye. Hope to see you again soon"));
-                //break;
+    /*
+     * This method prints the list of tasks.
+     */
+    private static void listTasks(ArrayList<Task> tasks) {
+        if (tasks.isEmpty()) {
+            System.out.println(" No tasks.");
+        } else {
+            System.out.println(" Here are the tasks in your list:");
+            for (int i = 0; i < tasks.size(); i++) {
+                Task task = tasks.get(i);
+                System.out.println(" " + (i + 1) + "." + task.getStatusIcon() + " " + task.getDescription());
             }
         }
-        private static String getTaskList(ArrayList<String>  list) {
-            StringBuilder task = new StringBuilder();
-            if(list.isEmpty()) {
-                task.append("There is no task in your list");
-            } else {
-                for(int i = 0; i < list.size(); i++) {
-                    task.append(i + 1).append(".").append(list.get(i)).append("\n");
+    }
+
+    public static void main(String[] args) {
+        greetings(); // when user runs the program, UI greets user
+
+        try (Scanner givenTask = new Scanner(System.in)) {  
+            ArrayList<Task> tasks = new ArrayList<>();
+
+            while (true) {
+                String command = givenTask.nextLine();
+                System.out.println("____________________________________________________________");
+                
+                // if user inputs "bye", UI prints goodbye message and exits the program
+                if (command.equalsIgnoreCase("bye")) {
+                    goodbye();
+                    break;
+                } else if (command.equalsIgnoreCase("list")) { // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList    
+                    listTasks(tasks);
+                
+                // split the command into two parts, "mark" and the task number
+                // e.g. "mark 1" will be split into "mark" and "1"
+                // the task number is then parsed into an integer
+                // the task number is then used to get the task from the ArrayList
+                // the task is then marked as done
+                // the UI prints the task that is marked as done
+                // if the task number is invalid, the UI prints an error message
+                } else if (command.startsWith("mark")) { // if user inputs "mark", UI marks the task as done
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsDone(true);
+                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                                    + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
+                        }
+                    }
+                // split the command into two parts, "unmark" and the task number
+                // e.g. "unmark 1" will be split into "unmark" and "1"
+                // the task number is then parsed into an integer
+                // the task number is then used to get the task from the ArrayList
+                // the task is then marked as not done yet
+                // the UI prints the task that is marked as not done yet
+                // if the task number is invalid, the UI prints an error message
+                } else if (command.startsWith("unmark")) {
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsUndone(true);
+                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                                    + task.getStatusIcon() + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
+                        }
+                    }
+                } else {
+                    tasks.add(new Task(command));
+                    echo(" added: " + command);
                 }
+                System.out.println("____________________________________________________________");
             }
-            return task.toString();
         }
     }
-
-
+}
diff --git a/src/main/java/Task.java b/src/main/java/Task.java
new file mode 100644
index 000000000..0b589191d
--- /dev/null
+++ b/src/main/java/Task.java
@@ -0,0 +1,27 @@
+public class Task {
+    protected String description;
+    protected boolean isDone;
+
+
+    public Task(String description) {
+        this.description = description;
+        this.isDone = false;
+    }
+
+    public String getStatusIcon() {
+        //return (isDone ? "\u2713" : "\u2718"); //return tick or X symbols
+        return (isDone ? "[X]" : "[ ]"); //return X symbols when done, else return empty space
+    }
+
+    public void markAsDone(boolean isDone) {
+        this.isDone = true;
+    }
+    
+    public void markAsUndone(boolean isDone) {
+        this.isDone = false;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+}

From 8b1d144a214cc8ced04def62ff6c18e6d13a5bec Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Tue, 5 Sep 2023 00:34:00 +0800
Subject: [PATCH 06/28] edited code

---
 src/main/java/Duke.java | 12 +++++++-----
 src/main/java/Task.java |  1 -
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 38c54a7e1..23232a4fc 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,11 +1,13 @@
-import java.util.Scanner;
+
+
 import java.util.ArrayList;
+import java.util.Scanner;
 
 public class Duke {
     /*
      * This method prints the greetings message when the user starts the program.
      */
-    public static void greetings() {
+    public static void greet() {
         String logo = "  ____                  \n"
                 + " |  _ \\  ___  _ __ ___  \n"
                 + " | | | |/ _ \\| '_ ` _ \\ \n"
@@ -34,7 +36,7 @@ public static void goodbye() {
      */
     public static void echo(String input) {
         System.out.println(input);
-    };
+    }
 
     /*
      * This method prints the list of tasks.
@@ -52,10 +54,10 @@ private static void listTasks(ArrayList<Task> tasks) {
     }
 
     public static void main(String[] args) {
-        greetings(); // when user runs the program, UI greets user
+        greet(); // when user runs the program, UI greets user
 
         try (Scanner givenTask = new Scanner(System.in)) {  
-            ArrayList<Task> tasks = new ArrayList<>();
+            ArrayList<Task> tasks = new ArrayList<Task>();
 
             while (true) {
                 String command = givenTask.nextLine();
diff --git a/src/main/java/Task.java b/src/main/java/Task.java
index 0b589191d..cff338d6e 100644
--- a/src/main/java/Task.java
+++ b/src/main/java/Task.java
@@ -9,7 +9,6 @@ public Task(String description) {
     }
 
     public String getStatusIcon() {
-        //return (isDone ? "\u2713" : "\u2718"); //return tick or X symbols
         return (isDone ? "[X]" : "[ ]"); //return X symbols when done, else return empty space
     }
 

From cdbc6b6a321c483a5cce7c2502cbd83e314ba4a3 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 6 Sep 2023 00:32:15 +0800
Subject: [PATCH 07/28] level-4 completed, edited code

---
 src/main/java/Deadline.java | 17 +++++++++++
 src/main/java/Duke.java     | 59 ++++++++++++++++++++++++++++++++-----
 src/main/java/Event.java    | 23 +++++++++++++++
 src/main/java/Task.java     |  6 +++-
 src/main/java/Todo.java     | 10 +++++++
 5 files changed, 106 insertions(+), 9 deletions(-)
 create mode 100644 src/main/java/Deadline.java
 create mode 100644 src/main/java/Event.java
 create mode 100644 src/main/java/Todo.java

diff --git a/src/main/java/Deadline.java b/src/main/java/Deadline.java
new file mode 100644
index 000000000..ca89bce00
--- /dev/null
+++ b/src/main/java/Deadline.java
@@ -0,0 +1,17 @@
+public class Deadline extends Task{
+    protected String by;
+
+    public Deadline(String description, String by) {
+        super(description);
+        this.by = by;
+    }
+
+    public String getBy() {
+        return this.by;
+    }
+
+    @Override
+    public String toString() {
+        return "[D]" + super.toString() + " (by: " + this.by + ")";
+    }
+}
diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 23232a4fc..493f71c26 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,4 +1,4 @@
-
+//package main.java;
 
 import java.util.ArrayList;
 import java.util.Scanner;
@@ -46,15 +46,24 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println(" No tasks.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-            for (int i = 0; i < tasks.size(); i++) {
-                Task task = tasks.get(i);
-                System.out.println(" " + (i + 1) + "." + task.getStatusIcon() + " " + task.getDescription());
+        for (int i = 0; i < tasks.size(); i++) {
+            Task task = tasks.get(i);
+            String taskType = task instanceof Todo ? "[T]" : (task instanceof Deadline ? "[D]" : "[E]");
+            String statusIcon = task.getStatusIcon();
+            String description = task.getDescription();
+            
+            if (task instanceof Deadline) {
+                description += " (by: " + ((Deadline) task).getBy() + ")";
+            } else if (task instanceof Event) {
+                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
             }
+            
+            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
         }
     }
-
+}
     public static void main(String[] args) {
-        greet(); // when user runs the program, UI greets user
+        greet();
 
         try (Scanner givenTask = new Scanner(System.in)) {  
             ArrayList<Task> tasks = new ArrayList<Task>();
@@ -62,8 +71,7 @@ public static void main(String[] args) {
             while (true) {
                 String command = givenTask.nextLine();
                 System.out.println("____________________________________________________________");
-                
-                // if user inputs "bye", UI prints goodbye message and exits the program
+
                 if (command.equalsIgnoreCase("bye")) {
                     goodbye();
                     break;
@@ -110,6 +118,41 @@ public static void main(String[] args) {
                             System.out.println(" Invalid task number.");
                         }
                     }
+                } else if (command.startsWith("todo ")) {
+                    // Handle adding a ToDo task
+                    String description = command.substring(5); // Remove "todo "
+                    tasks.add(new Todo(description));
+                    System.out.println(" Got it. I've added this task:");
+                    System.out.println("   " + tasks.get(tasks.size() - 1));
+                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                } else if (command.startsWith("deadline ")) {
+                    String[] parts = command.substring(9).split(" /by ");
+                    if (parts.length == 2) {
+                        // Handle adding a Deadline task
+                        String description = parts[0];
+                        String by = parts[1];
+                        tasks.add(new Deadline(description, by));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } else {
+                        System.out.println(" Invalid command.");
+                    }
+                } else if (command.startsWith("event ")) {
+                    // Handle adding an Event task
+                    String[] parts = command.substring(6).split(" /from ");
+                    if (parts.length == 2) {
+                        String description = parts[0];
+                        String[] timeParts = parts[1].split(" /to ");
+                        String from = timeParts[0];
+                        String to = timeParts[1];
+                        tasks.add(new Event(description, from, to));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } else {
+                        System.out.println(" Invalid event command format.");
+                    }
                 } else {
                     tasks.add(new Task(command));
                     echo(" added: " + command);
diff --git a/src/main/java/Event.java b/src/main/java/Event.java
new file mode 100644
index 000000000..0afd4c71a
--- /dev/null
+++ b/src/main/java/Event.java
@@ -0,0 +1,23 @@
+public class Event extends Task {
+    protected String from;
+    protected String to;
+
+    public Event(String description, String from, String to) {
+        super(description);
+        this.from = from;
+        this.to = to;
+    }
+
+    public String getFrom() {
+        return this.from;
+    }
+
+    public String getTo() {
+        return this.to;
+    }
+
+    @Override
+    public String toString() {
+        return "[E]" + super.toString() + "(from: " + this.from + " to: " + this.to + ")";
+    }
+}
diff --git a/src/main/java/Task.java b/src/main/java/Task.java
index cff338d6e..1ceabe3c0 100644
--- a/src/main/java/Task.java
+++ b/src/main/java/Task.java
@@ -20,7 +20,11 @@ public void markAsUndone(boolean isDone) {
         this.isDone = false;
     }
 
+    public String toString() {
+        return getStatusIcon() + " " + this.description;
+    }
+
     public String getDescription() {
-        return description;
+        return this.description;
     }
 }
diff --git a/src/main/java/Todo.java b/src/main/java/Todo.java
new file mode 100644
index 000000000..08ff10ce4
--- /dev/null
+++ b/src/main/java/Todo.java
@@ -0,0 +1,10 @@
+public class Todo extends Task {
+    public Todo (String description) {
+        super(description);
+    }
+
+    @Override
+    public String toString() {
+        return "[T]" + super.toString();
+    }
+}

From cb72979821e12cff1523a3f023b316043a1e8812 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 12:45:09 +0800
Subject: [PATCH 08/28] edited code

---
 src/main/java/Duke.java | 160 ++++++++++++++++++++++++++++------------
 src/main/java/Task.java |   2 +-
 2 files changed, 113 insertions(+), 49 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 493f71c26..6a7c4c161 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,9 +1,9 @@
-//package main.java;
-
 import java.util.ArrayList;
 import java.util.Scanner;
 
 public class Duke {
+    public static final String lineDivider = "____________________________________________________________";
+
     /*
      * This method prints the greetings message when the user starts the program.
      */
@@ -14,10 +14,10 @@ public static void greet() {
                 + " | |_| | (_) | | | | | |\n"
                 + " |____/ \\___/|_| |_| |_|\n";
         System.out.println("Hello from\n" + logo);
-        String greetings = "____________________________________________________________" + "\n" +
-                "Hello! I'm Dom" + "\n" +
-                "What can I do for you?" + "\n" +
-                "____________________________________________________________";
+        String greetings = lineDivider +
+                "\nHello! I'm Dom\n" +
+                "What can I do for you?\n" +
+                lineDivider;
         System.out.println(greetings);
     }
 
@@ -25,12 +25,26 @@ public static void greet() {
      * This method prints the goodbye message when the user exits the program.
      */
     public static void goodbye() {
-        String goodbye = "____________________________________________________________" + "\n" +
-                "Bye. Hope to see you again soon!" + "\n" +
-                "____________________________________________________________";
+        String goodbye = lineDivider +
+                "\nBye. Hope to see you again soon!\n" +
+                lineDivider;
         System.out.println(goodbye);
     }
 
+    public static void getHelp() {
+        String help = 
+                "\nHere are the list of commands that you can use:\n" +
+                "bye - exits the program\n" +
+                "list - lists all the tasks\n" +
+                "todo <description> - adds a ToDo task\n" +
+                "deadline <description> /by <time> - adds a Deadline task\n" +
+                "event <description> /from <time> /to <time> - adds an Event task\n" +
+                "mark <task number> - marks the task as done\n" +
+                "unmark <task number> - marks the task as not done yet\n" 
+                ;
+        System.out.println(help);
+    }
+
     /*
      * This method prints the input message.
      */
@@ -43,21 +57,25 @@ public static void echo(String input) {
      */
     private static void listTasks(ArrayList<Task> tasks) {
         if (tasks.isEmpty()) {
-            System.out.println(" No tasks.");
+            System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
         for (int i = 0; i < tasks.size(); i++) {
             Task task = tasks.get(i);
-            String taskType = task instanceof Todo ? "[T]" : (task instanceof Deadline ? "[D]" : "[E]");
+
+            /*
+            * checks if the task is a ToDo, Deadline or Event
+            * prints the task type, status icon and description
+            * */
+            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
             String statusIcon = task.getStatusIcon();
             String description = task.getDescription();
             
-            if (task instanceof Deadline) {
+            if (task.getClass().equals(Deadline.class)) {
                 description += " (by: " + ((Deadline) task).getBy() + ")";
-            } else if (task instanceof Event) {
+            } else if (task.getClass().equals(Event.class)) {
                 description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
             }
-            
             System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
         }
     }
@@ -66,26 +84,31 @@ public static void main(String[] args) {
         greet();
 
         try (Scanner givenTask = new Scanner(System.in)) {  
-            ArrayList<Task> tasks = new ArrayList<Task>();
-
+            ArrayList<Task> tasks = new ArrayList<>();
+            
             while (true) {
                 String command = givenTask.nextLine();
-                System.out.println("____________________________________________________________");
-
+                System.out.println(lineDivider);
+                
                 if (command.equalsIgnoreCase("bye")) {
                     goodbye();
                     break;
-                } else if (command.equalsIgnoreCase("list")) { // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList    
+                } else if (command.equalsIgnoreCase("list")) {
+                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
                     listTasks(tasks);
                 
-                // split the command into two parts, "mark" and the task number
-                // e.g. "mark 1" will be split into "mark" and "1"
-                // the task number is then parsed into an integer
-                // the task number is then used to get the task from the ArrayList
-                // the task is then marked as done
-                // the UI prints the task that is marked as done
-                // if the task number is invalid, the UI prints an error message
-                } else if (command.startsWith("mark")) { // if user inputs "mark", UI marks the task as done
+                /** 
+                * split the command into two parts, "mark" and the task number
+                 * e.g. "mark 1" will be split into "mark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as done
+                 * the UI prints the task that is marked as done
+                 * if the task number is invalid, the UI prints an error message
+                 */
+
+                } else if (command.startsWith("mark")) { 
+
                     String[] parts = command.split(" ");
                     if (parts.length == 2) {
                         int taskIndex = Integer.parseInt(parts[1]) - 1;
@@ -98,13 +121,15 @@ public static void main(String[] args) {
                             System.out.println(" Invalid task number.");
                         }
                     }
-                // split the command into two parts, "unmark" and the task number
-                // e.g. "unmark 1" will be split into "unmark" and "1"
-                // the task number is then parsed into an integer
-                // the task number is then used to get the task from the ArrayList
-                // the task is then marked as not done yet
-                // the UI prints the task that is marked as not done yet
-                // if the task number is invalid, the UI prints an error message
+                /**
+                 * split the command into two parts, "unmark" and the task number
+                 * e.g. "unmark 1" will be split into "unmark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as not done yet
+                 * the UI prints the task that is marked as not done yet
+                 * if the task number is invalid, the UI prints an error message
+                 */
                 } else if (command.startsWith("unmark")) {
                     String[] parts = command.split(" ");
                     if (parts.length == 2) {
@@ -118,17 +143,41 @@ public static void main(String[] args) {
                             System.out.println(" Invalid task number.");
                         }
                     }
+                
+                /**
+                 * Handle adding a ToDo task
+                 * e.g. "todo read book" will be split into "todo" and "read book"
+                 * the description is then parsed into a ToDo task.
+                 * the ToDo task is then added to the ArrayList
+                 * the UI prints the ToDo task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description is empty, the UI prints an error message
+                 */
                 } else if (command.startsWith("todo ")) {
-                    // Handle adding a ToDo task
-                    String description = command.substring(5); // Remove "todo "
-                    tasks.add(new Todo(description));
-                    System.out.println(" Got it. I've added this task:");
-                    System.out.println("   " + tasks.get(tasks.size() - 1));
-                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    try {
+                        if (command.substring(5).isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
+                        }
+                        tasks.add(new Todo (command.substring(5)));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } catch (Exception e) {
+                        System.out.println(e.getMessage());
+                    }
+                /**
+                 * Handle adding a Deadline task 
+                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
+                 * the description and by time is then parsed into a Deadline task.
+                 * the Deadline task is then added to the ArrayList
+                 * the UI prints the Deadline task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description or by time is empty, the UI prints an error message
+                 * if the by time is not in the correct format, the UI prints an error message
+                 */
                 } else if (command.startsWith("deadline ")) {
                     String[] parts = command.substring(9).split(" /by ");
-                    if (parts.length == 2) {
-                        // Handle adding a Deadline task
+                    if (parts.length == 2) {                  
                         String description = parts[0];
                         String by = parts[1];
                         tasks.add(new Deadline(description, by));
@@ -138,8 +187,18 @@ public static void main(String[] args) {
                     } else {
                         System.out.println(" Invalid command.");
                     }
+                /**
+                 * Handle adding an Event task
+                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
+                 * the description, from time and to time is then parsed into an Event task.
+                 * the Event task is then added to the ArrayList
+                 * the UI prints the Event task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description, from time or to time is empty, the UI prints an error message
+                 * if the from time or to time is not in the correct format, the UI prints an error message
+                 * if the from time is after the to time, the UI prints an error message
+                 */
                 } else if (command.startsWith("event ")) {
-                    // Handle adding an Event task
                     String[] parts = command.substring(6).split(" /from ");
                     if (parts.length == 2) {
                         String description = parts[0];
@@ -153,12 +212,17 @@ public static void main(String[] args) {
                     } else {
                         System.out.println(" Invalid event command format.");
                     }
-                } else {
-                    tasks.add(new Task(command));
-                    echo(" added: " + command);
+                } else if (command.startsWith("help")) {
+                    getHelp();
                 }
-                System.out.println("____________________________________________________________");
+                 else {
+                    System.out.println("Error: Invalid command.");
+                    System.out.println("If assistance is required, please type 'help' for more information.");
+                    //tasks.add(new Task(command));
+                    //echo(" added: " + command);
+                }
+                System.out.println(lineDivider);
             }
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/Task.java b/src/main/java/Task.java
index 1ceabe3c0..6d0e98293 100644
--- a/src/main/java/Task.java
+++ b/src/main/java/Task.java
@@ -9,7 +9,7 @@ public Task(String description) {
     }
 
     public String getStatusIcon() {
-        return (isDone ? "[X]" : "[ ]"); //return X symbols when done, else return empty space
+        return (isDone ? "[X]" : "[ ]"); 
     }
 
     public void markAsDone(boolean isDone) {

From 75ddef5646d6a5a92c521de48eedf3e72e8240f1 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 18:58:51 +0800
Subject: [PATCH 09/28] Level-5 increment + edit code

---
 src/main/java/Duke.java          | 353 ++++++++++++++++++-------------
 src/main/java/DukeException.java |   4 +
 2 files changed, 209 insertions(+), 148 deletions(-)
 create mode 100644 src/main/java/DukeException.java

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 6a7c4c161..137018acb 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,7 +2,7 @@
 import java.util.Scanner;
 
 public class Duke {
-    public static final String lineDivider = "____________________________________________________________";
+    public static final String lineDivider = "______________________________________________________________________";
 
     /*
      * This method prints the greetings message when the user starts the program.
@@ -32,16 +32,15 @@ public static void goodbye() {
     }
 
     public static void getHelp() {
-        String help = 
-                "\nHere are the list of commands that you can use:\n" +
+        String help = "\nHere are the list of commands that you can use:\n" +
                 "bye - exits the program\n" +
                 "list - lists all the tasks\n" +
                 "todo <description> - adds a ToDo task\n" +
                 "deadline <description> /by <time> - adds a Deadline task\n" +
                 "event <description> /from <time> /to <time> - adds an Event task\n" +
                 "mark <task number> - marks the task as done\n" +
-                "unmark <task number> - marks the task as not done yet\n" 
-                ;
+                "unmark <task number> - marks the task as not done yet\n";
+
         System.out.println(help);
     }
 
@@ -60,166 +59,224 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-        for (int i = 0; i < tasks.size(); i++) {
-            Task task = tasks.get(i);
-
-            /*
-            * checks if the task is a ToDo, Deadline or Event
-            * prints the task type, status icon and description
-            * */
-            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
-            String statusIcon = task.getStatusIcon();
-            String description = task.getDescription();
-            
-            if (task.getClass().equals(Deadline.class)) {
-                description += " (by: " + ((Deadline) task).getBy() + ")";
-            } else if (task.getClass().equals(Event.class)) {
-                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
+            for (int i = 0; i < tasks.size(); i++) {
+                Task task = tasks.get(i);
+
+                /*
+                 * checks if the task is a ToDo, Deadline or Event
+                 * prints the task type, status icon and description
+                 */
+                String taskType = task.getClass().equals(Todo.class) ? "[T]"
+                        : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
+                String statusIcon = task.getStatusIcon();
+                String description = task.getDescription();
+
+                if (task.getClass().equals(Deadline.class)) {
+                    description += " (by: " + ((Deadline) task).getBy() + ")";
+                } else if (task.getClass().equals(Event.class)) {
+                    description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
+                }
+                System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
             }
-            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
         }
     }
-}
+
     public static void main(String[] args) {
         greet();
 
-        try (Scanner givenTask = new Scanner(System.in)) {  
+        try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
-            
+
             while (true) {
                 String command = givenTask.nextLine();
                 System.out.println(lineDivider);
-                
-                if (command.equalsIgnoreCase("bye")) {
-                    goodbye();
-                    break;
-                } else if (command.equalsIgnoreCase("list")) {
-                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
-                    listTasks(tasks);
-                
-                /** 
-                * split the command into two parts, "mark" and the task number
-                 * e.g. "mark 1" will be split into "mark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as done
-                 * the UI prints the task that is marked as done
-                 * if the task number is invalid, the UI prints an error message
-                 */
 
-                } else if (command.startsWith("mark")) { 
-
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsDone(true);
-                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                    + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
+                try {
+                    if (command.equalsIgnoreCase("bye")) {
+                        goodbye();
+                        break;
+                    } else if (command.equalsIgnoreCase("list")) {
+                        // if user inputs "list", UI prints the list of tasks that is stored in the
+                        // ArrayList
+                        listTasks(tasks);
+
+                        /**
+                         * split the command into two parts, "mark" and the task number
+                         * e.g. "mark 1" will be split into "mark" and "1"
+                         * the task number is then parsed into an integer
+                         * the task number is then used to get the task from the ArrayList
+                         * the task is then marked as done
+                         * the UI prints the task that is marked as done
+                         * if the task number is invalid, the UI prints an error message
+                         */
+
+                    } else if (command.startsWith("mark")) {
+                        if (command.substring(5).isEmpty()) {
+                            System.out.println("Error: Task number cannot be empty\n");
+                            System.out.println("Please enter command in the format: mark <task number>");
                         }
-                    }
-                /**
-                 * split the command into two parts, "unmark" and the task number
-                 * e.g. "unmark 1" will be split into "unmark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as not done yet
-                 * the UI prints the task that is marked as not done yet
-                 * if the task number is invalid, the UI prints an error message
-                 */
-                } else if (command.startsWith("unmark")) {
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsUndone(true);
-                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                    + task.getStatusIcon() + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
+                        try {
+                            String[] parts = command.split(" ");
+                            if (parts.length == 2) {
+                                int taskIndex = Integer.parseInt(parts[1]) - 1;
+                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                                    Task task = tasks.get(taskIndex);
+                                    task.markAsDone(true);
+                                    System.out.println(
+                                            " Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                                                    + " " + task.getDescription());
+                                } else {
+                                    System.out.println(" Invalid task number.");
+                                }
+                            }
+                        } catch (NumberFormatException e) {
+                            System.out.println("Please enter a valid task number");
                         }
-                    }
-                
-                /**
-                 * Handle adding a ToDo task
-                 * e.g. "todo read book" will be split into "todo" and "read book"
-                 * the description is then parsed into a ToDo task.
-                 * the ToDo task is then added to the ArrayList
-                 * the UI prints the ToDo task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description is empty, the UI prints an error message
-                 */
-                } else if (command.startsWith("todo ")) {
-                    try {
-                        if (command.substring(5).isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
+                        /**
+                         * split the command into two parts, "unmark" and the task number
+                         * e.g. "unmark 1" will be split into "unmark" and "1"
+                         * the task number is then parsed into an integer
+                         * the task number is then used to get the task from the ArrayList
+                         * the task is then marked as not done yet
+                         * the UI prints the task that is marked as not done yet
+                         * if the task number is invalid, the UI prints an error message
+                         */
+                    } else if (command.startsWith("unmark")) {
+                        if (command.substring(7).isEmpty()) {
+                            System.out.println("Error: Task number cannot be empty\n");
+                            System.out.println("Please enter command in the format: unmark <task number>");
                         }
-                        tasks.add(new Todo (command.substring(5)));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } catch (Exception e) {
-                        System.out.println(e.getMessage());
-                    }
-                /**
-                 * Handle adding a Deadline task 
-                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
-                 * the description and by time is then parsed into a Deadline task.
-                 * the Deadline task is then added to the ArrayList
-                 * the UI prints the Deadline task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description or by time is empty, the UI prints an error message
-                 * if the by time is not in the correct format, the UI prints an error message
-                 */
-                } else if (command.startsWith("deadline ")) {
-                    String[] parts = command.substring(9).split(" /by ");
-                    if (parts.length == 2) {                  
-                        String description = parts[0];
-                        String by = parts[1];
-                        tasks.add(new Deadline(description, by));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } else {
-                        System.out.println(" Invalid command.");
-                    }
-                /**
-                 * Handle adding an Event task
-                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
-                 * the description, from time and to time is then parsed into an Event task.
-                 * the Event task is then added to the ArrayList
-                 * the UI prints the Event task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description, from time or to time is empty, the UI prints an error message
-                 * if the from time or to time is not in the correct format, the UI prints an error message
-                 * if the from time is after the to time, the UI prints an error message
-                 */
-                } else if (command.startsWith("event ")) {
-                    String[] parts = command.substring(6).split(" /from ");
-                    if (parts.length == 2) {
-                        String description = parts[0];
-                        String[] timeParts = parts[1].split(" /to ");
-                        String from = timeParts[0];
-                        String to = timeParts[1];
-                        tasks.add(new Event(description, from, to));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                        try {
+                            String[] parts = command.split(" ");
+                            if (parts.length == 2) {
+                                int taskIndex = Integer.parseInt(parts[1]) - 1;
+                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                                    Task task = tasks.get(taskIndex);
+                                    task.markAsUndone(true);
+                                    System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                                            + task.getStatusIcon() + " " + task.getDescription());
+                                } else {
+                                    System.out.println(" Invalid task number.");
+                                }
+                            }
+                        } catch (NumberFormatException e) {
+                            System.out.println("Please enter a valid task number");
+                        }
+
+                        /**
+                         * Handle adding a ToDo task
+                         * e.g. "todo read book" will be split into "todo" and "read book"
+                         * the description is then parsed into a ToDo task.
+                         * the ToDo task is then added to the ArrayList
+                         * the UI prints the ToDo task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description is empty, the UI prints an error message
+                         */
+                    } else if (command.startsWith("todo ")) {
+                        try {
+                            if (command.substring(5).isEmpty()) {
+                                throw new DukeException();
+                            }
+                            tasks.add(new Todo(command.substring(5)));
+                            System.out.println(" Got it. I've added this task:");
+                            System.out.println("   " + tasks.get(tasks.size() - 1));
+                            System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
+                            System.out.println("please enter command in the format: todo <description>");
+                        }
+                        /**
+                         * Handle adding a Deadline task
+                         * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return
+                         * book /by 2pm"
+                         * the description and by time is then parsed into a Deadline task.
+                         * the Deadline task is then added to the ArrayList
+                         * the UI prints the Deadline task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description or by time is empty, the UI prints an error message
+                         * if the by time is not in the correct format, the UI prints an error message
+                         */
+                    } else if (command.startsWith("deadline ")) {
+                        try {
+                            if (command.substring(9).isEmpty()) {
+                                throw new DukeException();
+                            }
+                            String[] parts = command.substring(9).split(" /by ");
+                            if (parts.length == 2) {
+                                String description = parts[0];
+                                String by = parts[1].trim();
+                                if (by.isEmpty()) {
+                                    throw new DukeException();
+                                }
+                                tasks.add(new Deadline(description, by));
+                                System.out.println(" Got it. I've added this task:");
+                                System.out.println("   " + tasks.get(tasks.size() - 1));
+                                System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                            } else {
+                                System.out.println(" Invalid command.");
+                            }
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
+                            System.out.println("please enter command in the format: deadline <description> /by <time>");
+                        }
+                        /**
+                         * Handle adding an Event task
+                         * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and
+                         * "project meeting /from 2pm /to 4pm"
+                         * the description, from time and to time is then parsed into an Event task.
+                         * the Event task is then added to the ArrayList
+                         * the UI prints the Event task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description, from time or to time is empty, the UI prints an error
+                         * message
+                         * if the from time or to time is not in the correct format, the UI prints an
+                         * error message
+                         * if the from time is after the to time, the UI prints an error message
+                         */
+                    } else if (command.startsWith("event ")) {
+                        try {
+                            String descriptionAndTime = command.substring(6).trim(); // Trim to handle leading/trailing spaces
+                    
+                            if (descriptionAndTime.isEmpty()) {
+                                throw new DukeException();
+                            }
+                    
+                            String[] parts = descriptionAndTime.split(" /from ");
+                    
+                            if (parts.length == 2) {
+                                String description = parts[0];
+                                String[] timeParts = parts[1].split(" /to ");
+                    
+                                if (timeParts.length == 2) {
+                                    String from = timeParts[0].trim(); // Trim to handle leading/trailing spaces
+                                    String to = timeParts[1].trim(); // Trim to handle leading/trailing spaces
+                    
+                                    //if (from.isEmpty() || to.isEmpty()) {
+                                        //throw new DukeException();
+                                    //}
+                    
+                                    tasks.add(new Event(description, from, to));
+                                    System.out.println(" Got it. I've added this task:");
+                                    System.out.println("   " + tasks.get(tasks.size() - 1));
+                                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                                } else {
+                                    throw new DukeException();
+                                }
+                            } else {
+                                System.out.println(" Invalid event command format.");
+                            }
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description and /from or /to time of an event cannot be empty.\n");
+                            System.out.println("Please enter the command in the format: event <description> /from <time> /to <time>");
+                        }
+                    } else if (command.startsWith("help")) {
+                        getHelp();
                     } else {
-                        System.out.println(" Invalid event command format.");
+                        throw new DukeException();
                     }
-                } else if (command.startsWith("help")) {
-                    getHelp();
-                }
-                 else {
-                    System.out.println("Error: Invalid command.");
+                } catch (DukeException e) {
+                    System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
                     System.out.println("If assistance is required, please type 'help' for more information.");
-                    //tasks.add(new Task(command));
-                    //echo(" added: " + command);
                 }
                 System.out.println(lineDivider);
             }
diff --git a/src/main/java/DukeException.java b/src/main/java/DukeException.java
new file mode 100644
index 000000000..6c48ce85a
--- /dev/null
+++ b/src/main/java/DukeException.java
@@ -0,0 +1,4 @@
+public class DukeException extends Exception{
+    
+}
+

From 41ac3310970987df65bffca4bc432eefd3d258f1 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 19:13:23 +0800
Subject: [PATCH 10/28] no message

---
 src/main/java/Duke.java | 339 +++++++++++++++++++++++++++-------------
 src/main/java/Task.java |   2 +-
 2 files changed, 231 insertions(+), 110 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 493f71c26..137018acb 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,9 +1,9 @@
-//package main.java;
-
 import java.util.ArrayList;
 import java.util.Scanner;
 
 public class Duke {
+    public static final String lineDivider = "______________________________________________________________________";
+
     /*
      * This method prints the greetings message when the user starts the program.
      */
@@ -14,10 +14,10 @@ public static void greet() {
                 + " | |_| | (_) | | | | | |\n"
                 + " |____/ \\___/|_| |_| |_|\n";
         System.out.println("Hello from\n" + logo);
-        String greetings = "____________________________________________________________" + "\n" +
-                "Hello! I'm Dom" + "\n" +
-                "What can I do for you?" + "\n" +
-                "____________________________________________________________";
+        String greetings = lineDivider +
+                "\nHello! I'm Dom\n" +
+                "What can I do for you?\n" +
+                lineDivider;
         System.out.println(greetings);
     }
 
@@ -25,12 +25,25 @@ public static void greet() {
      * This method prints the goodbye message when the user exits the program.
      */
     public static void goodbye() {
-        String goodbye = "____________________________________________________________" + "\n" +
-                "Bye. Hope to see you again soon!" + "\n" +
-                "____________________________________________________________";
+        String goodbye = lineDivider +
+                "\nBye. Hope to see you again soon!\n" +
+                lineDivider;
         System.out.println(goodbye);
     }
 
+    public static void getHelp() {
+        String help = "\nHere are the list of commands that you can use:\n" +
+                "bye - exits the program\n" +
+                "list - lists all the tasks\n" +
+                "todo <description> - adds a ToDo task\n" +
+                "deadline <description> /by <time> - adds a Deadline task\n" +
+                "event <description> /from <time> /to <time> - adds an Event task\n" +
+                "mark <task number> - marks the task as done\n" +
+                "unmark <task number> - marks the task as not done yet\n";
+
+        System.out.println(help);
+    }
+
     /*
      * This method prints the input message.
      */
@@ -43,122 +56,230 @@ public static void echo(String input) {
      */
     private static void listTasks(ArrayList<Task> tasks) {
         if (tasks.isEmpty()) {
-            System.out.println(" No tasks.");
+            System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-        for (int i = 0; i < tasks.size(); i++) {
-            Task task = tasks.get(i);
-            String taskType = task instanceof Todo ? "[T]" : (task instanceof Deadline ? "[D]" : "[E]");
-            String statusIcon = task.getStatusIcon();
-            String description = task.getDescription();
-            
-            if (task instanceof Deadline) {
-                description += " (by: " + ((Deadline) task).getBy() + ")";
-            } else if (task instanceof Event) {
-                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
+            for (int i = 0; i < tasks.size(); i++) {
+                Task task = tasks.get(i);
+
+                /*
+                 * checks if the task is a ToDo, Deadline or Event
+                 * prints the task type, status icon and description
+                 */
+                String taskType = task.getClass().equals(Todo.class) ? "[T]"
+                        : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
+                String statusIcon = task.getStatusIcon();
+                String description = task.getDescription();
+
+                if (task.getClass().equals(Deadline.class)) {
+                    description += " (by: " + ((Deadline) task).getBy() + ")";
+                } else if (task.getClass().equals(Event.class)) {
+                    description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
+                }
+                System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
             }
-            
-            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
         }
     }
-}
+
     public static void main(String[] args) {
         greet();
 
-        try (Scanner givenTask = new Scanner(System.in)) {  
-            ArrayList<Task> tasks = new ArrayList<Task>();
+        try (Scanner givenTask = new Scanner(System.in)) {
+            ArrayList<Task> tasks = new ArrayList<>();
 
             while (true) {
                 String command = givenTask.nextLine();
-                System.out.println("____________________________________________________________");
-
-                if (command.equalsIgnoreCase("bye")) {
-                    goodbye();
-                    break;
-                } else if (command.equalsIgnoreCase("list")) { // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList    
-                    listTasks(tasks);
-                
-                // split the command into two parts, "mark" and the task number
-                // e.g. "mark 1" will be split into "mark" and "1"
-                // the task number is then parsed into an integer
-                // the task number is then used to get the task from the ArrayList
-                // the task is then marked as done
-                // the UI prints the task that is marked as done
-                // if the task number is invalid, the UI prints an error message
-                } else if (command.startsWith("mark")) { // if user inputs "mark", UI marks the task as done
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsDone(true);
-                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                    + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
+                System.out.println(lineDivider);
+
+                try {
+                    if (command.equalsIgnoreCase("bye")) {
+                        goodbye();
+                        break;
+                    } else if (command.equalsIgnoreCase("list")) {
+                        // if user inputs "list", UI prints the list of tasks that is stored in the
+                        // ArrayList
+                        listTasks(tasks);
+
+                        /**
+                         * split the command into two parts, "mark" and the task number
+                         * e.g. "mark 1" will be split into "mark" and "1"
+                         * the task number is then parsed into an integer
+                         * the task number is then used to get the task from the ArrayList
+                         * the task is then marked as done
+                         * the UI prints the task that is marked as done
+                         * if the task number is invalid, the UI prints an error message
+                         */
+
+                    } else if (command.startsWith("mark")) {
+                        if (command.substring(5).isEmpty()) {
+                            System.out.println("Error: Task number cannot be empty\n");
+                            System.out.println("Please enter command in the format: mark <task number>");
                         }
-                    }
-                // split the command into two parts, "unmark" and the task number
-                // e.g. "unmark 1" will be split into "unmark" and "1"
-                // the task number is then parsed into an integer
-                // the task number is then used to get the task from the ArrayList
-                // the task is then marked as not done yet
-                // the UI prints the task that is marked as not done yet
-                // if the task number is invalid, the UI prints an error message
-                } else if (command.startsWith("unmark")) {
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsUndone(true);
-                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                    + task.getStatusIcon() + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
+                        try {
+                            String[] parts = command.split(" ");
+                            if (parts.length == 2) {
+                                int taskIndex = Integer.parseInt(parts[1]) - 1;
+                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                                    Task task = tasks.get(taskIndex);
+                                    task.markAsDone(true);
+                                    System.out.println(
+                                            " Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                                                    + " " + task.getDescription());
+                                } else {
+                                    System.out.println(" Invalid task number.");
+                                }
+                            }
+                        } catch (NumberFormatException e) {
+                            System.out.println("Please enter a valid task number");
                         }
-                    }
-                } else if (command.startsWith("todo ")) {
-                    // Handle adding a ToDo task
-                    String description = command.substring(5); // Remove "todo "
-                    tasks.add(new Todo(description));
-                    System.out.println(" Got it. I've added this task:");
-                    System.out.println("   " + tasks.get(tasks.size() - 1));
-                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                } else if (command.startsWith("deadline ")) {
-                    String[] parts = command.substring(9).split(" /by ");
-                    if (parts.length == 2) {
-                        // Handle adding a Deadline task
-                        String description = parts[0];
-                        String by = parts[1];
-                        tasks.add(new Deadline(description, by));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } else {
-                        System.out.println(" Invalid command.");
-                    }
-                } else if (command.startsWith("event ")) {
-                    // Handle adding an Event task
-                    String[] parts = command.substring(6).split(" /from ");
-                    if (parts.length == 2) {
-                        String description = parts[0];
-                        String[] timeParts = parts[1].split(" /to ");
-                        String from = timeParts[0];
-                        String to = timeParts[1];
-                        tasks.add(new Event(description, from, to));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                        /**
+                         * split the command into two parts, "unmark" and the task number
+                         * e.g. "unmark 1" will be split into "unmark" and "1"
+                         * the task number is then parsed into an integer
+                         * the task number is then used to get the task from the ArrayList
+                         * the task is then marked as not done yet
+                         * the UI prints the task that is marked as not done yet
+                         * if the task number is invalid, the UI prints an error message
+                         */
+                    } else if (command.startsWith("unmark")) {
+                        if (command.substring(7).isEmpty()) {
+                            System.out.println("Error: Task number cannot be empty\n");
+                            System.out.println("Please enter command in the format: unmark <task number>");
+                        }
+                        try {
+                            String[] parts = command.split(" ");
+                            if (parts.length == 2) {
+                                int taskIndex = Integer.parseInt(parts[1]) - 1;
+                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                                    Task task = tasks.get(taskIndex);
+                                    task.markAsUndone(true);
+                                    System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                                            + task.getStatusIcon() + " " + task.getDescription());
+                                } else {
+                                    System.out.println(" Invalid task number.");
+                                }
+                            }
+                        } catch (NumberFormatException e) {
+                            System.out.println("Please enter a valid task number");
+                        }
+
+                        /**
+                         * Handle adding a ToDo task
+                         * e.g. "todo read book" will be split into "todo" and "read book"
+                         * the description is then parsed into a ToDo task.
+                         * the ToDo task is then added to the ArrayList
+                         * the UI prints the ToDo task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description is empty, the UI prints an error message
+                         */
+                    } else if (command.startsWith("todo ")) {
+                        try {
+                            if (command.substring(5).isEmpty()) {
+                                throw new DukeException();
+                            }
+                            tasks.add(new Todo(command.substring(5)));
+                            System.out.println(" Got it. I've added this task:");
+                            System.out.println("   " + tasks.get(tasks.size() - 1));
+                            System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
+                            System.out.println("please enter command in the format: todo <description>");
+                        }
+                        /**
+                         * Handle adding a Deadline task
+                         * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return
+                         * book /by 2pm"
+                         * the description and by time is then parsed into a Deadline task.
+                         * the Deadline task is then added to the ArrayList
+                         * the UI prints the Deadline task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description or by time is empty, the UI prints an error message
+                         * if the by time is not in the correct format, the UI prints an error message
+                         */
+                    } else if (command.startsWith("deadline ")) {
+                        try {
+                            if (command.substring(9).isEmpty()) {
+                                throw new DukeException();
+                            }
+                            String[] parts = command.substring(9).split(" /by ");
+                            if (parts.length == 2) {
+                                String description = parts[0];
+                                String by = parts[1].trim();
+                                if (by.isEmpty()) {
+                                    throw new DukeException();
+                                }
+                                tasks.add(new Deadline(description, by));
+                                System.out.println(" Got it. I've added this task:");
+                                System.out.println("   " + tasks.get(tasks.size() - 1));
+                                System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                            } else {
+                                System.out.println(" Invalid command.");
+                            }
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
+                            System.out.println("please enter command in the format: deadline <description> /by <time>");
+                        }
+                        /**
+                         * Handle adding an Event task
+                         * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and
+                         * "project meeting /from 2pm /to 4pm"
+                         * the description, from time and to time is then parsed into an Event task.
+                         * the Event task is then added to the ArrayList
+                         * the UI prints the Event task that is added
+                         * the UI prints the number of tasks in the ArrayList
+                         * if the description, from time or to time is empty, the UI prints an error
+                         * message
+                         * if the from time or to time is not in the correct format, the UI prints an
+                         * error message
+                         * if the from time is after the to time, the UI prints an error message
+                         */
+                    } else if (command.startsWith("event ")) {
+                        try {
+                            String descriptionAndTime = command.substring(6).trim(); // Trim to handle leading/trailing spaces
+                    
+                            if (descriptionAndTime.isEmpty()) {
+                                throw new DukeException();
+                            }
+                    
+                            String[] parts = descriptionAndTime.split(" /from ");
+                    
+                            if (parts.length == 2) {
+                                String description = parts[0];
+                                String[] timeParts = parts[1].split(" /to ");
+                    
+                                if (timeParts.length == 2) {
+                                    String from = timeParts[0].trim(); // Trim to handle leading/trailing spaces
+                                    String to = timeParts[1].trim(); // Trim to handle leading/trailing spaces
+                    
+                                    //if (from.isEmpty() || to.isEmpty()) {
+                                        //throw new DukeException();
+                                    //}
+                    
+                                    tasks.add(new Event(description, from, to));
+                                    System.out.println(" Got it. I've added this task:");
+                                    System.out.println("   " + tasks.get(tasks.size() - 1));
+                                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                                } else {
+                                    throw new DukeException();
+                                }
+                            } else {
+                                System.out.println(" Invalid event command format.");
+                            }
+                        } catch (DukeException e) {
+                            System.out.println("☹ OOPS!!! The description and /from or /to time of an event cannot be empty.\n");
+                            System.out.println("Please enter the command in the format: event <description> /from <time> /to <time>");
+                        }
+                    } else if (command.startsWith("help")) {
+                        getHelp();
                     } else {
-                        System.out.println(" Invalid event command format.");
+                        throw new DukeException();
                     }
-                } else {
-                    tasks.add(new Task(command));
-                    echo(" added: " + command);
+                } catch (DukeException e) {
+                    System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
+                    System.out.println("If assistance is required, please type 'help' for more information.");
                 }
-                System.out.println("____________________________________________________________");
+                System.out.println(lineDivider);
             }
         }
     }
-}
+}
\ No newline at end of file
diff --git a/src/main/java/Task.java b/src/main/java/Task.java
index 1ceabe3c0..6d0e98293 100644
--- a/src/main/java/Task.java
+++ b/src/main/java/Task.java
@@ -9,7 +9,7 @@ public Task(String description) {
     }
 
     public String getStatusIcon() {
-        return (isDone ? "[X]" : "[ ]"); //return X symbols when done, else return empty space
+        return (isDone ? "[X]" : "[ ]"); 
     }
 
     public void markAsDone(boolean isDone) {

From e8ec87639a5e9b357c3beca454959354117b1759 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 19:14:24 +0800
Subject: [PATCH 11/28] Revert "Level-5 increment + edit code"

This reverts commit 75ddef5646d6a5a92c521de48eedf3e72e8240f1.
---
 src/main/java/Duke.java | 353 +++++++++++++++++-----------------------
 1 file changed, 148 insertions(+), 205 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 137018acb..6a7c4c161 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,7 +2,7 @@
 import java.util.Scanner;
 
 public class Duke {
-    public static final String lineDivider = "______________________________________________________________________";
+    public static final String lineDivider = "____________________________________________________________";
 
     /*
      * This method prints the greetings message when the user starts the program.
@@ -32,15 +32,16 @@ public static void goodbye() {
     }
 
     public static void getHelp() {
-        String help = "\nHere are the list of commands that you can use:\n" +
+        String help = 
+                "\nHere are the list of commands that you can use:\n" +
                 "bye - exits the program\n" +
                 "list - lists all the tasks\n" +
                 "todo <description> - adds a ToDo task\n" +
                 "deadline <description> /by <time> - adds a Deadline task\n" +
                 "event <description> /from <time> /to <time> - adds an Event task\n" +
                 "mark <task number> - marks the task as done\n" +
-                "unmark <task number> - marks the task as not done yet\n";
-
+                "unmark <task number> - marks the task as not done yet\n" 
+                ;
         System.out.println(help);
     }
 
@@ -59,224 +60,166 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-            for (int i = 0; i < tasks.size(); i++) {
-                Task task = tasks.get(i);
-
-                /*
-                 * checks if the task is a ToDo, Deadline or Event
-                 * prints the task type, status icon and description
-                 */
-                String taskType = task.getClass().equals(Todo.class) ? "[T]"
-                        : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
-                String statusIcon = task.getStatusIcon();
-                String description = task.getDescription();
-
-                if (task.getClass().equals(Deadline.class)) {
-                    description += " (by: " + ((Deadline) task).getBy() + ")";
-                } else if (task.getClass().equals(Event.class)) {
-                    description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
-                }
-                System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
+        for (int i = 0; i < tasks.size(); i++) {
+            Task task = tasks.get(i);
+
+            /*
+            * checks if the task is a ToDo, Deadline or Event
+            * prints the task type, status icon and description
+            * */
+            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
+            String statusIcon = task.getStatusIcon();
+            String description = task.getDescription();
+            
+            if (task.getClass().equals(Deadline.class)) {
+                description += " (by: " + ((Deadline) task).getBy() + ")";
+            } else if (task.getClass().equals(Event.class)) {
+                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
             }
+            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
         }
     }
-
+}
     public static void main(String[] args) {
         greet();
 
-        try (Scanner givenTask = new Scanner(System.in)) {
+        try (Scanner givenTask = new Scanner(System.in)) {  
             ArrayList<Task> tasks = new ArrayList<>();
-
+            
             while (true) {
                 String command = givenTask.nextLine();
                 System.out.println(lineDivider);
+                
+                if (command.equalsIgnoreCase("bye")) {
+                    goodbye();
+                    break;
+                } else if (command.equalsIgnoreCase("list")) {
+                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
+                    listTasks(tasks);
+                
+                /** 
+                * split the command into two parts, "mark" and the task number
+                 * e.g. "mark 1" will be split into "mark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as done
+                 * the UI prints the task that is marked as done
+                 * if the task number is invalid, the UI prints an error message
+                 */
 
-                try {
-                    if (command.equalsIgnoreCase("bye")) {
-                        goodbye();
-                        break;
-                    } else if (command.equalsIgnoreCase("list")) {
-                        // if user inputs "list", UI prints the list of tasks that is stored in the
-                        // ArrayList
-                        listTasks(tasks);
-
-                        /**
-                         * split the command into two parts, "mark" and the task number
-                         * e.g. "mark 1" will be split into "mark" and "1"
-                         * the task number is then parsed into an integer
-                         * the task number is then used to get the task from the ArrayList
-                         * the task is then marked as done
-                         * the UI prints the task that is marked as done
-                         * if the task number is invalid, the UI prints an error message
-                         */
-
-                    } else if (command.startsWith("mark")) {
-                        if (command.substring(5).isEmpty()) {
-                            System.out.println("Error: Task number cannot be empty\n");
-                            System.out.println("Please enter command in the format: mark <task number>");
-                        }
-                        try {
-                            String[] parts = command.split(" ");
-                            if (parts.length == 2) {
-                                int taskIndex = Integer.parseInt(parts[1]) - 1;
-                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                                    Task task = tasks.get(taskIndex);
-                                    task.markAsDone(true);
-                                    System.out.println(
-                                            " Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                                    + " " + task.getDescription());
-                                } else {
-                                    System.out.println(" Invalid task number.");
-                                }
-                            }
-                        } catch (NumberFormatException e) {
-                            System.out.println("Please enter a valid task number");
-                        }
-                        /**
-                         * split the command into two parts, "unmark" and the task number
-                         * e.g. "unmark 1" will be split into "unmark" and "1"
-                         * the task number is then parsed into an integer
-                         * the task number is then used to get the task from the ArrayList
-                         * the task is then marked as not done yet
-                         * the UI prints the task that is marked as not done yet
-                         * if the task number is invalid, the UI prints an error message
-                         */
-                    } else if (command.startsWith("unmark")) {
-                        if (command.substring(7).isEmpty()) {
-                            System.out.println("Error: Task number cannot be empty\n");
-                            System.out.println("Please enter command in the format: unmark <task number>");
-                        }
-                        try {
-                            String[] parts = command.split(" ");
-                            if (parts.length == 2) {
-                                int taskIndex = Integer.parseInt(parts[1]) - 1;
-                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                                    Task task = tasks.get(taskIndex);
-                                    task.markAsUndone(true);
-                                    System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                            + task.getStatusIcon() + " " + task.getDescription());
-                                } else {
-                                    System.out.println(" Invalid task number.");
-                                }
-                            }
-                        } catch (NumberFormatException e) {
-                            System.out.println("Please enter a valid task number");
-                        }
-
-                        /**
-                         * Handle adding a ToDo task
-                         * e.g. "todo read book" will be split into "todo" and "read book"
-                         * the description is then parsed into a ToDo task.
-                         * the ToDo task is then added to the ArrayList
-                         * the UI prints the ToDo task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description is empty, the UI prints an error message
-                         */
-                    } else if (command.startsWith("todo ")) {
-                        try {
-                            if (command.substring(5).isEmpty()) {
-                                throw new DukeException();
-                            }
-                            tasks.add(new Todo(command.substring(5)));
-                            System.out.println(" Got it. I've added this task:");
-                            System.out.println("   " + tasks.get(tasks.size() - 1));
-                            System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
-                            System.out.println("please enter command in the format: todo <description>");
+                } else if (command.startsWith("mark")) { 
+
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsDone(true);
+                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                                    + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
                         }
-                        /**
-                         * Handle adding a Deadline task
-                         * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return
-                         * book /by 2pm"
-                         * the description and by time is then parsed into a Deadline task.
-                         * the Deadline task is then added to the ArrayList
-                         * the UI prints the Deadline task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description or by time is empty, the UI prints an error message
-                         * if the by time is not in the correct format, the UI prints an error message
-                         */
-                    } else if (command.startsWith("deadline ")) {
-                        try {
-                            if (command.substring(9).isEmpty()) {
-                                throw new DukeException();
-                            }
-                            String[] parts = command.substring(9).split(" /by ");
-                            if (parts.length == 2) {
-                                String description = parts[0];
-                                String by = parts[1].trim();
-                                if (by.isEmpty()) {
-                                    throw new DukeException();
-                                }
-                                tasks.add(new Deadline(description, by));
-                                System.out.println(" Got it. I've added this task:");
-                                System.out.println("   " + tasks.get(tasks.size() - 1));
-                                System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                            } else {
-                                System.out.println(" Invalid command.");
-                            }
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
-                            System.out.println("please enter command in the format: deadline <description> /by <time>");
+                    }
+                /**
+                 * split the command into two parts, "unmark" and the task number
+                 * e.g. "unmark 1" will be split into "unmark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as not done yet
+                 * the UI prints the task that is marked as not done yet
+                 * if the task number is invalid, the UI prints an error message
+                 */
+                } else if (command.startsWith("unmark")) {
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsUndone(true);
+                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                                    + task.getStatusIcon() + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
                         }
-                        /**
-                         * Handle adding an Event task
-                         * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and
-                         * "project meeting /from 2pm /to 4pm"
-                         * the description, from time and to time is then parsed into an Event task.
-                         * the Event task is then added to the ArrayList
-                         * the UI prints the Event task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description, from time or to time is empty, the UI prints an error
-                         * message
-                         * if the from time or to time is not in the correct format, the UI prints an
-                         * error message
-                         * if the from time is after the to time, the UI prints an error message
-                         */
-                    } else if (command.startsWith("event ")) {
-                        try {
-                            String descriptionAndTime = command.substring(6).trim(); // Trim to handle leading/trailing spaces
-                    
-                            if (descriptionAndTime.isEmpty()) {
-                                throw new DukeException();
-                            }
-                    
-                            String[] parts = descriptionAndTime.split(" /from ");
-                    
-                            if (parts.length == 2) {
-                                String description = parts[0];
-                                String[] timeParts = parts[1].split(" /to ");
-                    
-                                if (timeParts.length == 2) {
-                                    String from = timeParts[0].trim(); // Trim to handle leading/trailing spaces
-                                    String to = timeParts[1].trim(); // Trim to handle leading/trailing spaces
-                    
-                                    //if (from.isEmpty() || to.isEmpty()) {
-                                        //throw new DukeException();
-                                    //}
-                    
-                                    tasks.add(new Event(description, from, to));
-                                    System.out.println(" Got it. I've added this task:");
-                                    System.out.println("   " + tasks.get(tasks.size() - 1));
-                                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                                } else {
-                                    throw new DukeException();
-                                }
-                            } else {
-                                System.out.println(" Invalid event command format.");
-                            }
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description and /from or /to time of an event cannot be empty.\n");
-                            System.out.println("Please enter the command in the format: event <description> /from <time> /to <time>");
+                    }
+                
+                /**
+                 * Handle adding a ToDo task
+                 * e.g. "todo read book" will be split into "todo" and "read book"
+                 * the description is then parsed into a ToDo task.
+                 * the ToDo task is then added to the ArrayList
+                 * the UI prints the ToDo task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description is empty, the UI prints an error message
+                 */
+                } else if (command.startsWith("todo ")) {
+                    try {
+                        if (command.substring(5).isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
                         }
-                    } else if (command.startsWith("help")) {
-                        getHelp();
+                        tasks.add(new Todo (command.substring(5)));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } catch (Exception e) {
+                        System.out.println(e.getMessage());
+                    }
+                /**
+                 * Handle adding a Deadline task 
+                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
+                 * the description and by time is then parsed into a Deadline task.
+                 * the Deadline task is then added to the ArrayList
+                 * the UI prints the Deadline task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description or by time is empty, the UI prints an error message
+                 * if the by time is not in the correct format, the UI prints an error message
+                 */
+                } else if (command.startsWith("deadline ")) {
+                    String[] parts = command.substring(9).split(" /by ");
+                    if (parts.length == 2) {                  
+                        String description = parts[0];
+                        String by = parts[1];
+                        tasks.add(new Deadline(description, by));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } else {
+                        System.out.println(" Invalid command.");
+                    }
+                /**
+                 * Handle adding an Event task
+                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
+                 * the description, from time and to time is then parsed into an Event task.
+                 * the Event task is then added to the ArrayList
+                 * the UI prints the Event task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description, from time or to time is empty, the UI prints an error message
+                 * if the from time or to time is not in the correct format, the UI prints an error message
+                 * if the from time is after the to time, the UI prints an error message
+                 */
+                } else if (command.startsWith("event ")) {
+                    String[] parts = command.substring(6).split(" /from ");
+                    if (parts.length == 2) {
+                        String description = parts[0];
+                        String[] timeParts = parts[1].split(" /to ");
+                        String from = timeParts[0];
+                        String to = timeParts[1];
+                        tasks.add(new Event(description, from, to));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
                     } else {
-                        throw new DukeException();
+                        System.out.println(" Invalid event command format.");
                     }
-                } catch (DukeException e) {
-                    System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
+                } else if (command.startsWith("help")) {
+                    getHelp();
+                }
+                 else {
+                    System.out.println("Error: Invalid command.");
                     System.out.println("If assistance is required, please type 'help' for more information.");
+                    //tasks.add(new Task(command));
+                    //echo(" added: " + command);
                 }
                 System.out.println(lineDivider);
             }

From f50b1a3ef472a79eb10c51299f305f23a9eb9678 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 19:38:27 +0800
Subject: [PATCH 12/28] changes to code

---
 src/main/java/Duke.java | 175 ----------------------------------------
 1 file changed, 175 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index eade37163..137018acb 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,11 +2,7 @@
 import java.util.Scanner;
 
 public class Duke {
-<<<<<<< HEAD
-    public static final String lineDivider = "____________________________________________________________";
-=======
     public static final String lineDivider = "______________________________________________________________________";
->>>>>>> Branch-Level-5
 
     /*
      * This method prints the greetings message when the user starts the program.
@@ -36,25 +32,15 @@ public static void goodbye() {
     }
 
     public static void getHelp() {
-<<<<<<< HEAD
-        String help = 
-                "\nHere are the list of commands that you can use:\n" +
-=======
         String help = "\nHere are the list of commands that you can use:\n" +
->>>>>>> Branch-Level-5
                 "bye - exits the program\n" +
                 "list - lists all the tasks\n" +
                 "todo <description> - adds a ToDo task\n" +
                 "deadline <description> /by <time> - adds a Deadline task\n" +
                 "event <description> /from <time> /to <time> - adds an Event task\n" +
                 "mark <task number> - marks the task as done\n" +
-<<<<<<< HEAD
-                "unmark <task number> - marks the task as not done yet\n" 
-                ;
-=======
                 "unmark <task number> - marks the task as not done yet\n";
 
->>>>>>> Branch-Level-5
         System.out.println(help);
     }
 
@@ -73,25 +59,6 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-<<<<<<< HEAD
-        for (int i = 0; i < tasks.size(); i++) {
-            Task task = tasks.get(i);
-
-            /*
-            * checks if the task is a ToDo, Deadline or Event
-            * prints the task type, status icon and description
-            * */
-            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
-            String statusIcon = task.getStatusIcon();
-            String description = task.getDescription();
-            
-            if (task.getClass().equals(Deadline.class)) {
-                description += " (by: " + ((Deadline) task).getBy() + ")";
-            } else if (task.getClass().equals(Event.class)) {
-                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
-            }
-            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
-=======
             for (int i = 0; i < tasks.size(); i++) {
                 Task task = tasks.get(i);
 
@@ -111,116 +78,12 @@ private static void listTasks(ArrayList<Task> tasks) {
                 }
                 System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
             }
->>>>>>> Branch-Level-5
         }
     }
 
     public static void main(String[] args) {
         greet();
 
-<<<<<<< HEAD
-        try (Scanner givenTask = new Scanner(System.in)) {  
-            ArrayList<Task> tasks = new ArrayList<>();
-            
-            while (true) {
-                String command = givenTask.nextLine();
-                System.out.println(lineDivider);
-                
-                if (command.equalsIgnoreCase("bye")) {
-                    goodbye();
-                    break;
-                } else if (command.equalsIgnoreCase("list")) {
-                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
-                    listTasks(tasks);
-                
-                /** 
-                * split the command into two parts, "mark" and the task number
-                 * e.g. "mark 1" will be split into "mark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as done
-                 * the UI prints the task that is marked as done
-                 * if the task number is invalid, the UI prints an error message
-                 */
-
-                } else if (command.startsWith("mark")) { 
-
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsDone(true);
-                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                    + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
-                        }
-                    }
-                /**
-                 * split the command into two parts, "unmark" and the task number
-                 * e.g. "unmark 1" will be split into "unmark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as not done yet
-                 * the UI prints the task that is marked as not done yet
-                 * if the task number is invalid, the UI prints an error message
-                 */
-                } else if (command.startsWith("unmark")) {
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsUndone(true);
-                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                    + task.getStatusIcon() + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
-                        }
-                    }
-                
-                /**
-                 * Handle adding a ToDo task
-                 * e.g. "todo read book" will be split into "todo" and "read book"
-                 * the description is then parsed into a ToDo task.
-                 * the ToDo task is then added to the ArrayList
-                 * the UI prints the ToDo task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description is empty, the UI prints an error message
-                 */
-                } else if (command.startsWith("todo ")) {
-                    try {
-                        if (command.substring(5).isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
-                        }
-                        tasks.add(new Todo (command.substring(5)));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } catch (Exception e) {
-                        System.out.println(e.getMessage());
-                    }
-                /**
-                 * Handle adding a Deadline task 
-                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
-                 * the description and by time is then parsed into a Deadline task.
-                 * the Deadline task is then added to the ArrayList
-                 * the UI prints the Deadline task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description or by time is empty, the UI prints an error message
-                 * if the by time is not in the correct format, the UI prints an error message
-                 */
-                } else if (command.startsWith("deadline ")) {
-                    String[] parts = command.substring(9).split(" /by ");
-                    if (parts.length == 2) {                  
-                        String description = parts[0];
-                        String by = parts[1];
-                        tasks.add(new Deadline(description, by));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-=======
         try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
 
@@ -408,51 +271,13 @@ public static void main(String[] args) {
                         }
                     } else if (command.startsWith("help")) {
                         getHelp();
->>>>>>> Branch-Level-5
                     } else {
                         throw new DukeException();
                     }
-<<<<<<< HEAD
-                /**
-                 * Handle adding an Event task
-                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
-                 * the description, from time and to time is then parsed into an Event task.
-                 * the Event task is then added to the ArrayList
-                 * the UI prints the Event task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description, from time or to time is empty, the UI prints an error message
-                 * if the from time or to time is not in the correct format, the UI prints an error message
-                 * if the from time is after the to time, the UI prints an error message
-                 */
-                } else if (command.startsWith("event ")) {
-                    String[] parts = command.substring(6).split(" /from ");
-                    if (parts.length == 2) {
-                        String description = parts[0];
-                        String[] timeParts = parts[1].split(" /to ");
-                        String from = timeParts[0];
-                        String to = timeParts[1];
-                        tasks.add(new Event(description, from, to));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } else {
-                        System.out.println(" Invalid event command format.");
-                    }
-                } else if (command.startsWith("help")) {
-                    getHelp();
-                }
-                 else {
-                    System.out.println("Error: Invalid command.");
-                    System.out.println("If assistance is required, please type 'help' for more information.");
-                    //tasks.add(new Task(command));
-                    //echo(" added: " + command);
-                }
-=======
                 } catch (DukeException e) {
                     System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
                     System.out.println("If assistance is required, please type 'help' for more information.");
                 }
->>>>>>> Branch-Level-5
                 System.out.println(lineDivider);
             }
         }

From 4607c8541316c574ac80df9acfd1a651f31f82f8 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 19:41:54 +0800
Subject: [PATCH 13/28] Revert "changes to code"

This reverts commit f50b1a3ef472a79eb10c51299f305f23a9eb9678.
---
 src/main/java/Duke.java | 175 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 175 insertions(+)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 137018acb..eade37163 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,7 +2,11 @@
 import java.util.Scanner;
 
 public class Duke {
+<<<<<<< HEAD
+    public static final String lineDivider = "____________________________________________________________";
+=======
     public static final String lineDivider = "______________________________________________________________________";
+>>>>>>> Branch-Level-5
 
     /*
      * This method prints the greetings message when the user starts the program.
@@ -32,15 +36,25 @@ public static void goodbye() {
     }
 
     public static void getHelp() {
+<<<<<<< HEAD
+        String help = 
+                "\nHere are the list of commands that you can use:\n" +
+=======
         String help = "\nHere are the list of commands that you can use:\n" +
+>>>>>>> Branch-Level-5
                 "bye - exits the program\n" +
                 "list - lists all the tasks\n" +
                 "todo <description> - adds a ToDo task\n" +
                 "deadline <description> /by <time> - adds a Deadline task\n" +
                 "event <description> /from <time> /to <time> - adds an Event task\n" +
                 "mark <task number> - marks the task as done\n" +
+<<<<<<< HEAD
+                "unmark <task number> - marks the task as not done yet\n" 
+                ;
+=======
                 "unmark <task number> - marks the task as not done yet\n";
 
+>>>>>>> Branch-Level-5
         System.out.println(help);
     }
 
@@ -59,6 +73,25 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
+<<<<<<< HEAD
+        for (int i = 0; i < tasks.size(); i++) {
+            Task task = tasks.get(i);
+
+            /*
+            * checks if the task is a ToDo, Deadline or Event
+            * prints the task type, status icon and description
+            * */
+            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
+            String statusIcon = task.getStatusIcon();
+            String description = task.getDescription();
+            
+            if (task.getClass().equals(Deadline.class)) {
+                description += " (by: " + ((Deadline) task).getBy() + ")";
+            } else if (task.getClass().equals(Event.class)) {
+                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
+            }
+            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
+=======
             for (int i = 0; i < tasks.size(); i++) {
                 Task task = tasks.get(i);
 
@@ -78,12 +111,116 @@ private static void listTasks(ArrayList<Task> tasks) {
                 }
                 System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
             }
+>>>>>>> Branch-Level-5
         }
     }
 
     public static void main(String[] args) {
         greet();
 
+<<<<<<< HEAD
+        try (Scanner givenTask = new Scanner(System.in)) {  
+            ArrayList<Task> tasks = new ArrayList<>();
+            
+            while (true) {
+                String command = givenTask.nextLine();
+                System.out.println(lineDivider);
+                
+                if (command.equalsIgnoreCase("bye")) {
+                    goodbye();
+                    break;
+                } else if (command.equalsIgnoreCase("list")) {
+                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
+                    listTasks(tasks);
+                
+                /** 
+                * split the command into two parts, "mark" and the task number
+                 * e.g. "mark 1" will be split into "mark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as done
+                 * the UI prints the task that is marked as done
+                 * if the task number is invalid, the UI prints an error message
+                 */
+
+                } else if (command.startsWith("mark")) { 
+
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsDone(true);
+                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                                    + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
+                        }
+                    }
+                /**
+                 * split the command into two parts, "unmark" and the task number
+                 * e.g. "unmark 1" will be split into "unmark" and "1"
+                 * the task number is then parsed into an integer
+                 * the task number is then used to get the task from the ArrayList
+                 * the task is then marked as not done yet
+                 * the UI prints the task that is marked as not done yet
+                 * if the task number is invalid, the UI prints an error message
+                 */
+                } else if (command.startsWith("unmark")) {
+                    String[] parts = command.split(" ");
+                    if (parts.length == 2) {
+                        int taskIndex = Integer.parseInt(parts[1]) - 1;
+                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                            Task task = tasks.get(taskIndex);
+                            task.markAsUndone(true);
+                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                                    + task.getStatusIcon() + " " + task.getDescription());
+                        } else {
+                            System.out.println(" Invalid task number.");
+                        }
+                    }
+                
+                /**
+                 * Handle adding a ToDo task
+                 * e.g. "todo read book" will be split into "todo" and "read book"
+                 * the description is then parsed into a ToDo task.
+                 * the ToDo task is then added to the ArrayList
+                 * the UI prints the ToDo task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description is empty, the UI prints an error message
+                 */
+                } else if (command.startsWith("todo ")) {
+                    try {
+                        if (command.substring(5).isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
+                        }
+                        tasks.add(new Todo (command.substring(5)));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } catch (Exception e) {
+                        System.out.println(e.getMessage());
+                    }
+                /**
+                 * Handle adding a Deadline task 
+                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
+                 * the description and by time is then parsed into a Deadline task.
+                 * the Deadline task is then added to the ArrayList
+                 * the UI prints the Deadline task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description or by time is empty, the UI prints an error message
+                 * if the by time is not in the correct format, the UI prints an error message
+                 */
+                } else if (command.startsWith("deadline ")) {
+                    String[] parts = command.substring(9).split(" /by ");
+                    if (parts.length == 2) {                  
+                        String description = parts[0];
+                        String by = parts[1];
+                        tasks.add(new Deadline(description, by));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+=======
         try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
 
@@ -271,13 +408,51 @@ public static void main(String[] args) {
                         }
                     } else if (command.startsWith("help")) {
                         getHelp();
+>>>>>>> Branch-Level-5
                     } else {
                         throw new DukeException();
                     }
+<<<<<<< HEAD
+                /**
+                 * Handle adding an Event task
+                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
+                 * the description, from time and to time is then parsed into an Event task.
+                 * the Event task is then added to the ArrayList
+                 * the UI prints the Event task that is added
+                 * the UI prints the number of tasks in the ArrayList
+                 * if the description, from time or to time is empty, the UI prints an error message
+                 * if the from time or to time is not in the correct format, the UI prints an error message
+                 * if the from time is after the to time, the UI prints an error message
+                 */
+                } else if (command.startsWith("event ")) {
+                    String[] parts = command.substring(6).split(" /from ");
+                    if (parts.length == 2) {
+                        String description = parts[0];
+                        String[] timeParts = parts[1].split(" /to ");
+                        String from = timeParts[0];
+                        String to = timeParts[1];
+                        tasks.add(new Event(description, from, to));
+                        System.out.println(" Got it. I've added this task:");
+                        System.out.println("   " + tasks.get(tasks.size() - 1));
+                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
+                    } else {
+                        System.out.println(" Invalid event command format.");
+                    }
+                } else if (command.startsWith("help")) {
+                    getHelp();
+                }
+                 else {
+                    System.out.println("Error: Invalid command.");
+                    System.out.println("If assistance is required, please type 'help' for more information.");
+                    //tasks.add(new Task(command));
+                    //echo(" added: " + command);
+                }
+=======
                 } catch (DukeException e) {
                     System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
                     System.out.println("If assistance is required, please type 'help' for more information.");
                 }
+>>>>>>> Branch-Level-5
                 System.out.println(lineDivider);
             }
         }

From 4729a1e2b48db5a977250546c7b00bd76fcafe6c Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 19:42:27 +0800
Subject: [PATCH 14/28] edited code

---
 src/main/java/Duke.java | 175 ----------------------------------------
 1 file changed, 175 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index eade37163..137018acb 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -2,11 +2,7 @@
 import java.util.Scanner;
 
 public class Duke {
-<<<<<<< HEAD
-    public static final String lineDivider = "____________________________________________________________";
-=======
     public static final String lineDivider = "______________________________________________________________________";
->>>>>>> Branch-Level-5
 
     /*
      * This method prints the greetings message when the user starts the program.
@@ -36,25 +32,15 @@ public static void goodbye() {
     }
 
     public static void getHelp() {
-<<<<<<< HEAD
-        String help = 
-                "\nHere are the list of commands that you can use:\n" +
-=======
         String help = "\nHere are the list of commands that you can use:\n" +
->>>>>>> Branch-Level-5
                 "bye - exits the program\n" +
                 "list - lists all the tasks\n" +
                 "todo <description> - adds a ToDo task\n" +
                 "deadline <description> /by <time> - adds a Deadline task\n" +
                 "event <description> /from <time> /to <time> - adds an Event task\n" +
                 "mark <task number> - marks the task as done\n" +
-<<<<<<< HEAD
-                "unmark <task number> - marks the task as not done yet\n" 
-                ;
-=======
                 "unmark <task number> - marks the task as not done yet\n";
 
->>>>>>> Branch-Level-5
         System.out.println(help);
     }
 
@@ -73,25 +59,6 @@ private static void listTasks(ArrayList<Task> tasks) {
             System.out.println("Error: No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
-<<<<<<< HEAD
-        for (int i = 0; i < tasks.size(); i++) {
-            Task task = tasks.get(i);
-
-            /*
-            * checks if the task is a ToDo, Deadline or Event
-            * prints the task type, status icon and description
-            * */
-            String taskType = task.getClass().equals(Todo.class) ? "[T]" : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
-            String statusIcon = task.getStatusIcon();
-            String description = task.getDescription();
-            
-            if (task.getClass().equals(Deadline.class)) {
-                description += " (by: " + ((Deadline) task).getBy() + ")";
-            } else if (task.getClass().equals(Event.class)) {
-                description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
-            }
-            System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
-=======
             for (int i = 0; i < tasks.size(); i++) {
                 Task task = tasks.get(i);
 
@@ -111,116 +78,12 @@ private static void listTasks(ArrayList<Task> tasks) {
                 }
                 System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
             }
->>>>>>> Branch-Level-5
         }
     }
 
     public static void main(String[] args) {
         greet();
 
-<<<<<<< HEAD
-        try (Scanner givenTask = new Scanner(System.in)) {  
-            ArrayList<Task> tasks = new ArrayList<>();
-            
-            while (true) {
-                String command = givenTask.nextLine();
-                System.out.println(lineDivider);
-                
-                if (command.equalsIgnoreCase("bye")) {
-                    goodbye();
-                    break;
-                } else if (command.equalsIgnoreCase("list")) {
-                    // if user inputs "list", UI prints the list of tasks that is stored in the ArrayList
-                    listTasks(tasks);
-                
-                /** 
-                * split the command into two parts, "mark" and the task number
-                 * e.g. "mark 1" will be split into "mark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as done
-                 * the UI prints the task that is marked as done
-                 * if the task number is invalid, the UI prints an error message
-                 */
-
-                } else if (command.startsWith("mark")) { 
-
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsDone(true);
-                            System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                    + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
-                        }
-                    }
-                /**
-                 * split the command into two parts, "unmark" and the task number
-                 * e.g. "unmark 1" will be split into "unmark" and "1"
-                 * the task number is then parsed into an integer
-                 * the task number is then used to get the task from the ArrayList
-                 * the task is then marked as not done yet
-                 * the UI prints the task that is marked as not done yet
-                 * if the task number is invalid, the UI prints an error message
-                 */
-                } else if (command.startsWith("unmark")) {
-                    String[] parts = command.split(" ");
-                    if (parts.length == 2) {
-                        int taskIndex = Integer.parseInt(parts[1]) - 1;
-                        if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                            Task task = tasks.get(taskIndex);
-                            task.markAsUndone(true);
-                            System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                    + task.getStatusIcon() + " " + task.getDescription());
-                        } else {
-                            System.out.println(" Invalid task number.");
-                        }
-                    }
-                
-                /**
-                 * Handle adding a ToDo task
-                 * e.g. "todo read book" will be split into "todo" and "read book"
-                 * the description is then parsed into a ToDo task.
-                 * the ToDo task is then added to the ArrayList
-                 * the UI prints the ToDo task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description is empty, the UI prints an error message
-                 */
-                } else if (command.startsWith("todo ")) {
-                    try {
-                        if (command.substring(5).isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
-                        }
-                        tasks.add(new Todo (command.substring(5)));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } catch (Exception e) {
-                        System.out.println(e.getMessage());
-                    }
-                /**
-                 * Handle adding a Deadline task 
-                 * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return book /by 2pm"
-                 * the description and by time is then parsed into a Deadline task.
-                 * the Deadline task is then added to the ArrayList
-                 * the UI prints the Deadline task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description or by time is empty, the UI prints an error message
-                 * if the by time is not in the correct format, the UI prints an error message
-                 */
-                } else if (command.startsWith("deadline ")) {
-                    String[] parts = command.substring(9).split(" /by ");
-                    if (parts.length == 2) {                  
-                        String description = parts[0];
-                        String by = parts[1];
-                        tasks.add(new Deadline(description, by));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-=======
         try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
 
@@ -408,51 +271,13 @@ public static void main(String[] args) {
                         }
                     } else if (command.startsWith("help")) {
                         getHelp();
->>>>>>> Branch-Level-5
                     } else {
                         throw new DukeException();
                     }
-<<<<<<< HEAD
-                /**
-                 * Handle adding an Event task
-                 * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and "project meeting /from 2pm /to 4pm"
-                 * the description, from time and to time is then parsed into an Event task.
-                 * the Event task is then added to the ArrayList
-                 * the UI prints the Event task that is added
-                 * the UI prints the number of tasks in the ArrayList
-                 * if the description, from time or to time is empty, the UI prints an error message
-                 * if the from time or to time is not in the correct format, the UI prints an error message
-                 * if the from time is after the to time, the UI prints an error message
-                 */
-                } else if (command.startsWith("event ")) {
-                    String[] parts = command.substring(6).split(" /from ");
-                    if (parts.length == 2) {
-                        String description = parts[0];
-                        String[] timeParts = parts[1].split(" /to ");
-                        String from = timeParts[0];
-                        String to = timeParts[1];
-                        tasks.add(new Event(description, from, to));
-                        System.out.println(" Got it. I've added this task:");
-                        System.out.println("   " + tasks.get(tasks.size() - 1));
-                        System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                    } else {
-                        System.out.println(" Invalid event command format.");
-                    }
-                } else if (command.startsWith("help")) {
-                    getHelp();
-                }
-                 else {
-                    System.out.println("Error: Invalid command.");
-                    System.out.println("If assistance is required, please type 'help' for more information.");
-                    //tasks.add(new Task(command));
-                    //echo(" added: " + command);
-                }
-=======
                 } catch (DukeException e) {
                     System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
                     System.out.println("If assistance is required, please type 'help' for more information.");
                 }
->>>>>>> Branch-Level-5
                 System.out.println(lineDivider);
             }
         }

From 6469a2f190575c36a9d4afb8a218d131e6f254e0 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 13 Sep 2023 22:34:08 +0800
Subject: [PATCH 15/28] included packages

---
 src/main/java/Duke.java                      | 6 ++++++
 src/main/java/{ => tasks}/Deadline.java      | 4 ++++
 src/main/java/{ => tasks}/DukeException.java | 4 ++++
 src/main/java/{ => tasks}/Event.java         | 4 ++++
 src/main/java/{ => tasks}/Task.java          | 2 ++
 src/main/java/{ => tasks}/Todo.java          | 4 ++++
 6 files changed, 24 insertions(+)
 rename src/main/java/{ => tasks}/Deadline.java (90%)
 rename src/main/java/{ => tasks}/DukeException.java (60%)
 rename src/main/java/{ => tasks}/Event.java (93%)
 rename src/main/java/{ => tasks}/Task.java (97%)
 rename src/main/java/{ => tasks}/Todo.java (84%)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 137018acb..6a381b569 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,6 +1,12 @@
 import java.util.ArrayList;
 import java.util.Scanner;
 
+import tasks.Deadline;
+import tasks.Event;
+import tasks.Task;
+import tasks.Todo;
+import tasks.DukeException;
+
 public class Duke {
     public static final String lineDivider = "______________________________________________________________________";
 
diff --git a/src/main/java/Deadline.java b/src/main/java/tasks/Deadline.java
similarity index 90%
rename from src/main/java/Deadline.java
rename to src/main/java/tasks/Deadline.java
index ca89bce00..ef2c11797 100644
--- a/src/main/java/Deadline.java
+++ b/src/main/java/tasks/Deadline.java
@@ -1,3 +1,7 @@
+package tasks;
+
+import tasks.Task;
+
 public class Deadline extends Task{
     protected String by;
 
diff --git a/src/main/java/DukeException.java b/src/main/java/tasks/DukeException.java
similarity index 60%
rename from src/main/java/DukeException.java
rename to src/main/java/tasks/DukeException.java
index 6c48ce85a..0ef80686e 100644
--- a/src/main/java/DukeException.java
+++ b/src/main/java/tasks/DukeException.java
@@ -1,3 +1,7 @@
+package tasks;
+
+import tasks.Task;
+
 public class DukeException extends Exception{
     
 }
diff --git a/src/main/java/Event.java b/src/main/java/tasks/Event.java
similarity index 93%
rename from src/main/java/Event.java
rename to src/main/java/tasks/Event.java
index 0afd4c71a..89a900516 100644
--- a/src/main/java/Event.java
+++ b/src/main/java/tasks/Event.java
@@ -1,3 +1,7 @@
+package tasks;
+
+import tasks.Task;
+
 public class Event extends Task {
     protected String from;
     protected String to;
diff --git a/src/main/java/Task.java b/src/main/java/tasks/Task.java
similarity index 97%
rename from src/main/java/Task.java
rename to src/main/java/tasks/Task.java
index 6d0e98293..9bd9be9f1 100644
--- a/src/main/java/Task.java
+++ b/src/main/java/tasks/Task.java
@@ -1,3 +1,5 @@
+package tasks;
+
 public class Task {
     protected String description;
     protected boolean isDone;
diff --git a/src/main/java/Todo.java b/src/main/java/tasks/Todo.java
similarity index 84%
rename from src/main/java/Todo.java
rename to src/main/java/tasks/Todo.java
index 08ff10ce4..3989a50f8 100644
--- a/src/main/java/Todo.java
+++ b/src/main/java/tasks/Todo.java
@@ -1,3 +1,7 @@
+package tasks;
+
+import tasks.Task;
+
 public class Todo extends Task {
     public Todo (String description) {
         super(description);

From 96270394a96b906cda19a85b674b2f1dbd78cf14 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Tue, 19 Sep 2023 23:19:29 +0800
Subject: [PATCH 16/28] edited code: change from else if statements to case
 statements

---
 src/main/java/Duke.java           | 453 +++++++++++++++++-------------
 src/main/java/tasks/Deadline.java |   3 +
 2 files changed, 258 insertions(+), 198 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 6a381b569..3af6f8151 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -9,7 +9,24 @@
 
 public class Duke {
     public static final String lineDivider = "______________________________________________________________________";
+    private static final String COMMAND_EXIT = "bye";
+    private static final String COMMAND_LIST = "list";
+    private static final String COMMAND_TODO = "todo";
+    private static final String COMMAND_DEADLINE = "deadline";
+    private static final String COMMAND_EVENT = "event";
+    private static final String COMMAND_MARK = "mark";
+    private static final String COMMAND_UNMARK = "unmark";
+    private static final String COMMAND_DELETE = "delete";
 
+    private static final String HELP_MESSAGE = "\nHere are the list of commands that you can use:\n"
+            + COMMAND_EXIT + " - exits the program\n"
+            + COMMAND_LIST + " - lists all the tasks\n"
+            + COMMAND_TODO + " <description> - adds a ToDo task\n"
+            + COMMAND_DEADLINE + " <description> /by <time> - adds a Deadline task\n"
+            + COMMAND_EVENT + " <description> /from <time> /to <time> - adds an Event task\n"
+            + COMMAND_MARK + " <task number> - marks the task as done\n"
+            + COMMAND_UNMARK + " <task number> - marks the task as not done yet\n"
+            + COMMAND_DELETE + " <task number> - deletes the task\n";
     /*
      * This method prints the greetings message when the user starts the program.
      */
@@ -31,24 +48,10 @@ public static void greet() {
      * This method prints the goodbye message when the user exits the program.
      */
     public static void goodbye() {
-        String goodbye = lineDivider +
-                "\nBye. Hope to see you again soon!\n" +
-                lineDivider;
-        System.out.println(goodbye);
+        echo("bye");
+        System.out.println("\nBye. Hope to see you again soon!");
     }
 
-    public static void getHelp() {
-        String help = "\nHere are the list of commands that you can use:\n" +
-                "bye - exits the program\n" +
-                "list - lists all the tasks\n" +
-                "todo <description> - adds a ToDo task\n" +
-                "deadline <description> /by <time> - adds a Deadline task\n" +
-                "event <description> /from <time> /to <time> - adds an Event task\n" +
-                "mark <task number> - marks the task as done\n" +
-                "unmark <task number> - marks the task as not done yet\n";
-
-        System.out.println(help);
-    }
 
     /*
      * This method prints the input message.
@@ -62,7 +65,7 @@ public static void echo(String input) {
      */
     private static void listTasks(ArrayList<Task> tasks) {
         if (tasks.isEmpty()) {
-            System.out.println("Error: No tasks is available.");
+            System.out.println("ERROR: ☹ OOPS!!! No tasks is available.");
         } else {
             System.out.println(" Here are the tasks in your list:");
             for (int i = 0; i < tasks.size(); i++) {
@@ -87,198 +90,252 @@ private static void listTasks(ArrayList<Task> tasks) {
         }
     }
 
+    /*
+     * This method marks the task as done.
+     *
+     * splits the command into two parts: command type and task number
+     * e.g. mark 1 will be split into "mark" and "1"
+     * the task number is then parsed into an integer
+     * the task number is then used to get the task from the list of tasks
+     * If the task number is invalid, it will print an error message.
+     * If the task number is valid, it will print the task that is marked as done.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the task number is empty or not an integer
+     * @throws NumberFormatException if the task number is not an integer
+     */
+    private static void markTask(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if (parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+            int taskIndex = Integer.parseInt(parts[1]) - 1;
+            if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                Task task = tasks.get(taskIndex);
+                task.markAsDone(true);
+                System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
+                        + " " + task.getDescription());
+            } else {
+                System.out.println("ERROR: ☹ OOPS!!! Invalid task number.");
+            }
+        } catch (DukeException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
+            System.out.println("Please enter command in the format: mark <task number>");
+        } catch (NumberFormatException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            System.out.println("Please enter command in the format: mark <task number>");
+        }
+    }
+
+    /*
+     * This method marks the task as not done yet.
+     *
+     * splits the command into two parts: command type and task number
+     * e.g. unmark 1 will be split into "unmark" and "1"
+     * the task number is then parsed into an integer
+     * the task number is then used to get the task from the list of tasks
+     * If the task number is invalid, it will print an error message.
+     * If the task number is valid, it will print the task that is marked as not done yet.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the task number is empty or not an integer
+     * @throws NumberFormatException if the task number is not an integer
+     */
+    private static void unmarkTask(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if (parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+
+            int taskIndex = Integer.parseInt(parts[1]) - 1;
+            if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                Task task = tasks.get(taskIndex);
+                task.markAsUndone(true);
+                System.out.println("OK, I've marked this task as not done yet:\n" + " "
+                        + task.getStatusIcon() + " " + task.getDescription());
+            } else {
+                System.out.println("Error: Invalid task number.");
+            }
+        } catch (DukeException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
+            System.out.println("Please enter command in the format: unmark <task number>");
+        } catch (NumberFormatException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            System.out.println("Please enter command in the format: unmark <task number>");
+        }
+    }
+
+
+    /*
+     * This method adds a ToDo task.
+     * splits the command into two parts: command type and description
+     * e.g. todo read book will be split into "todo" and "read book"
+     * the description is then used to create a new ToDo task
+     * the new ToDo task is then added to the list of tasks
+     * If the description is empty, it will print an error message.
+     * If the description is not empty, it will print the new ToDo task.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the description is empty
+     * @throws NumberFormatException if the task number is not an integer
+     *
+     */
+    private static void addTodo(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if (parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+            tasks.add(new Todo(parts[1]));
+            System.out.println("Got it. I've added this task:");
+            System.out.println("  " + tasks.get(tasks.size() - 1));
+            System.out.println("Now you have " + tasks.size() + " tasks in the list.");
+        } catch (DukeException e) {
+            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
+            System.out.println("please enter command in the format: todo <description>");
+        }
+    }
+
+    /*
+     * This method adds a Deadline task.
+     * splits the command into two parts: command type and description
+     * e.g. deadline return book /by 2pm will be split into "deadline" and "return book /by 2pm"
+     * the description is then used to create a new Deadline task
+     * the new Deadline task is then added to the list of tasks
+     * If the description is empty, it will print an error message.
+     * If the description is not empty, it will print the new Deadline task.
+     * If the description is not empty, but the time is empty, it will print an error message.
+     * If the description is not empty, but the time is not empty, it will print the new Deadline task.
+     * If the description is not empty, but the time is not empty, but the time is invalid, it will print an error message.
+     * If the description is not empty, but the time is not empty, but the time is valid, it will print the new Deadline task.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the description is empty
+     *
+     *
+     */
+    private static void addDeadline(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if (parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+            String[] deadlineParts = parts[1].split(" /by ");
+            if (deadlineParts.length == 2) {
+                String description = deadlineParts[0];
+                String by = deadlineParts[1].trim();
+                tasks.add(new Deadline(description, by));
+                System.out.println("Got it. I've added this task:");
+                System.out.println("  " + tasks.get(tasks.size() - 1));
+                System.out.println("Now you have " + tasks.size() + " tasks in the list.");
+            } else {
+                System.out.println("Invalid command.");
+            }
+        } catch (DukeException e) {
+            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
+            System.out.println("please enter command in the format: deadline <description> /by <time>");
+        }
+    }
+
+    /*
+     * This method adds an Event task.
+     * splits the command into two parts: command type and description
+     * e.g. event project meeting /from 2pm /to 4pm will be split into "event" and "project meeting /from 2pm /to 4pm"
+     * the description is then used to create a new Event task
+     * the new Event task is then added to the list of tasks
+     * If the description is empty, it will print an error message.
+     * If the description is not empty, it will print the new Event task.
+     * If the description is not empty, but the time is empty, it will print an error message.
+     * If the description is not empty, but the time is not empty, it will print the new Event task.
+     * If the description is not empty, but the time is not empty, but the time is invalid, it will print an error message.
+     * If the description is not empty, but the time is not empty, but the time is valid, it will print the new Event task.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the description is empty
+     *
+     */
+    private static void addEvent(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if (parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+            String[] eventParts = parts[1].split(" /from ");
+            if (eventParts.length == 2) {
+                String description = eventParts[0];
+                String[] timeParts = eventParts[1].split(" /to ");
+                if (timeParts.length == 2) {
+                    String from = timeParts[0].trim();
+                    String to = timeParts[1].trim();
+                    tasks.add(new Event(description, from, to));
+                    System.out.println("Got it. I've added this task:");
+                    System.out.println("  " + tasks.get(tasks.size() - 1));
+                    System.out.println("Now you have " + tasks.size() + " tasks in the list.");
+                } else {
+                    System.out.println("Invalid command.");
+                }
+            } else {
+                System.out.println("Invalid command.");
+            }
+        } catch (DukeException e) {
+            System.out.println("☹ OOPS!!! The description of an event cannot be empty.\n");
+            System.out.println("please enter command in the format: event <description> /from <time> /to <time>");
+        }
+    }
+
     public static void main(String[] args) {
         greet();
 
         try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
 
-            while (true) {
-                String command = givenTask.nextLine();
+
+            while(true) {
+                String command = givenTask.nextLine().trim();
                 System.out.println(lineDivider);
 
-                try {
-                    if (command.equalsIgnoreCase("bye")) {
-                        goodbye();
-                        break;
-                    } else if (command.equalsIgnoreCase("list")) {
-                        // if user inputs "list", UI prints the list of tasks that is stored in the
-                        // ArrayList
-                        listTasks(tasks);
+                String[] parts = command.split(" ", 2);
+                String commandType = parts.length > 0 ? parts[0] : "";
+
+                try{
+                    switch(commandType.toLowerCase()){
+                        case "bye":
+                            goodbye();
+                            break;
+
+                        case "list":
+                            listTasks(tasks);
+                            break;
+
+                        case "help":
+                            System.out.println(HELP_MESSAGE);
+                            break;
+
+                        case "mark":
+                            markTask(tasks, parts);
+                            break;
+
+                        case "unmark":
+                            unmarkTask(tasks, parts);
+                            break;
+
+                        case "todo":
+                            addTodo(tasks, parts);
+                            break;
 
-                        /**
-                         * split the command into two parts, "mark" and the task number
-                         * e.g. "mark 1" will be split into "mark" and "1"
-                         * the task number is then parsed into an integer
-                         * the task number is then used to get the task from the ArrayList
-                         * the task is then marked as done
-                         * the UI prints the task that is marked as done
-                         * if the task number is invalid, the UI prints an error message
-                         */
+                        case "deadline":
+                            addDeadline(tasks, parts);
+                            break;
 
-                    } else if (command.startsWith("mark")) {
-                        if (command.substring(5).isEmpty()) {
-                            System.out.println("Error: Task number cannot be empty\n");
-                            System.out.println("Please enter command in the format: mark <task number>");
-                        }
-                        try {
-                            String[] parts = command.split(" ");
-                            if (parts.length == 2) {
-                                int taskIndex = Integer.parseInt(parts[1]) - 1;
-                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                                    Task task = tasks.get(taskIndex);
-                                    task.markAsDone(true);
-                                    System.out.println(
-                                            " Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                                                    + " " + task.getDescription());
-                                } else {
-                                    System.out.println(" Invalid task number.");
-                                }
-                            }
-                        } catch (NumberFormatException e) {
-                            System.out.println("Please enter a valid task number");
-                        }
-                        /**
-                         * split the command into two parts, "unmark" and the task number
-                         * e.g. "unmark 1" will be split into "unmark" and "1"
-                         * the task number is then parsed into an integer
-                         * the task number is then used to get the task from the ArrayList
-                         * the task is then marked as not done yet
-                         * the UI prints the task that is marked as not done yet
-                         * if the task number is invalid, the UI prints an error message
-                         */
-                    } else if (command.startsWith("unmark")) {
-                        if (command.substring(7).isEmpty()) {
-                            System.out.println("Error: Task number cannot be empty\n");
-                            System.out.println("Please enter command in the format: unmark <task number>");
-                        }
-                        try {
-                            String[] parts = command.split(" ");
-                            if (parts.length == 2) {
-                                int taskIndex = Integer.parseInt(parts[1]) - 1;
-                                if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                                    Task task = tasks.get(taskIndex);
-                                    task.markAsUndone(true);
-                                    System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                                            + task.getStatusIcon() + " " + task.getDescription());
-                                } else {
-                                    System.out.println(" Invalid task number.");
-                                }
-                            }
-                        } catch (NumberFormatException e) {
-                            System.out.println("Please enter a valid task number");
-                        }
+                        case "event":
+                            addEvent(tasks, parts);
+                            break;
 
-                        /**
-                         * Handle adding a ToDo task
-                         * e.g. "todo read book" will be split into "todo" and "read book"
-                         * the description is then parsed into a ToDo task.
-                         * the ToDo task is then added to the ArrayList
-                         * the UI prints the ToDo task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description is empty, the UI prints an error message
-                         */
-                    } else if (command.startsWith("todo ")) {
-                        try {
-                            if (command.substring(5).isEmpty()) {
-                                throw new DukeException();
-                            }
-                            tasks.add(new Todo(command.substring(5)));
-                            System.out.println(" Got it. I've added this task:");
-                            System.out.println("   " + tasks.get(tasks.size() - 1));
-                            System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
-                            System.out.println("please enter command in the format: todo <description>");
-                        }
-                        /**
-                         * Handle adding a Deadline task
-                         * e.g. "deadline return book /by 2pm" will be split into "deadline" and "return
-                         * book /by 2pm"
-                         * the description and by time is then parsed into a Deadline task.
-                         * the Deadline task is then added to the ArrayList
-                         * the UI prints the Deadline task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description or by time is empty, the UI prints an error message
-                         * if the by time is not in the correct format, the UI prints an error message
-                         */
-                    } else if (command.startsWith("deadline ")) {
-                        try {
-                            if (command.substring(9).isEmpty()) {
-                                throw new DukeException();
-                            }
-                            String[] parts = command.substring(9).split(" /by ");
-                            if (parts.length == 2) {
-                                String description = parts[0];
-                                String by = parts[1].trim();
-                                if (by.isEmpty()) {
-                                    throw new DukeException();
-                                }
-                                tasks.add(new Deadline(description, by));
-                                System.out.println(" Got it. I've added this task:");
-                                System.out.println("   " + tasks.get(tasks.size() - 1));
-                                System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                            } else {
-                                System.out.println(" Invalid command.");
-                            }
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
-                            System.out.println("please enter command in the format: deadline <description> /by <time>");
-                        }
-                        /**
-                         * Handle adding an Event task
-                         * e.g. "event project meeting /from 2pm /to 4pm" will be split into "event" and
-                         * "project meeting /from 2pm /to 4pm"
-                         * the description, from time and to time is then parsed into an Event task.
-                         * the Event task is then added to the ArrayList
-                         * the UI prints the Event task that is added
-                         * the UI prints the number of tasks in the ArrayList
-                         * if the description, from time or to time is empty, the UI prints an error
-                         * message
-                         * if the from time or to time is not in the correct format, the UI prints an
-                         * error message
-                         * if the from time is after the to time, the UI prints an error message
-                         */
-                    } else if (command.startsWith("event ")) {
-                        try {
-                            String descriptionAndTime = command.substring(6).trim(); // Trim to handle leading/trailing spaces
-                    
-                            if (descriptionAndTime.isEmpty()) {
-                                throw new DukeException();
-                            }
-                    
-                            String[] parts = descriptionAndTime.split(" /from ");
-                    
-                            if (parts.length == 2) {
-                                String description = parts[0];
-                                String[] timeParts = parts[1].split(" /to ");
-                    
-                                if (timeParts.length == 2) {
-                                    String from = timeParts[0].trim(); // Trim to handle leading/trailing spaces
-                                    String to = timeParts[1].trim(); // Trim to handle leading/trailing spaces
-                    
-                                    //if (from.isEmpty() || to.isEmpty()) {
-                                        //throw new DukeException();
-                                    //}
-                    
-                                    tasks.add(new Event(description, from, to));
-                                    System.out.println(" Got it. I've added this task:");
-                                    System.out.println("   " + tasks.get(tasks.size() - 1));
-                                    System.out.println(" Now you have " + tasks.size() + " tasks in the list.");
-                                } else {
-                                    throw new DukeException();
-                                }
-                            } else {
-                                System.out.println(" Invalid event command format.");
-                            }
-                        } catch (DukeException e) {
-                            System.out.println("☹ OOPS!!! The description and /from or /to time of an event cannot be empty.\n");
-                            System.out.println("Please enter the command in the format: event <description> /from <time> /to <time>");
-                        }
-                    } else if (command.startsWith("help")) {
-                        getHelp();
-                    } else {
-                        throw new DukeException();
+                        default:
+                            echo(command);
+                            throw new DukeException();
                     }
                 } catch (DukeException e) {
                     System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
diff --git a/src/main/java/tasks/Deadline.java b/src/main/java/tasks/Deadline.java
index ef2c11797..8ae6ef758 100644
--- a/src/main/java/tasks/Deadline.java
+++ b/src/main/java/tasks/Deadline.java
@@ -7,6 +7,9 @@ public class Deadline extends Task{
 
     public Deadline(String description, String by) {
         super(description);
+        if (description == null || description.trim().isEmpty()) {
+            throw new IllegalArgumentException("description cannot be empty");
+        }
         this.by = by;
     }
 

From 1bb1859d16da1eac45f29b9b73d217e8d537f49c Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Tue, 19 Sep 2023 23:24:41 +0800
Subject: [PATCH 17/28] Level-6 increment done

---
 src/main/java/Duke.java | 46 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 3af6f8151..62f9946d3 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,6 +1,11 @@
 import java.util.ArrayList;
 import java.util.Scanner;
 
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+
+
 import tasks.Deadline;
 import tasks.Event;
 import tasks.Task;
@@ -284,6 +289,43 @@ private static void addEvent(ArrayList<Task> tasks, String[] parts) {
             System.out.println("please enter command in the format: event <description> /from <time> /to <time>");
         }
     }
+    /*
+     * This method deletes a task.
+     *
+     * splits the command into two parts: command type and task number
+     * e.g. delete 1 will be split into "delete" and "1"
+     * the task number is then parsed into an integer
+     * If the task number is invalid, it will print an error message.
+     * if the task number is valid, it will print the task that is deleted.
+     *
+     * @param tasks the list of tasks
+     * @param parts the command that is split into two parts
+     * @throws DukeException if the task number is empty or not an integer
+     * @throws NumberFormatException if the task number is not an integer
+     *
+     */
+    private static void deleteTask(ArrayList<Task> tasks, String[] parts) {
+        try {
+            if(parts.length < 2 || parts[1].isEmpty()) {
+                throw new DukeException();
+            }
+            int taskIndex = Integer.parseInt(parts[1]) - 1;
+            if (taskIndex >= 0 && taskIndex < tasks.size()) {
+                Task removeTask = tasks.remove(taskIndex);
+                System.out.println("Noted. I've removed this task:");
+                System.out.println("  " + removeTask);
+                System.out.println("Now you have " + tasks.size() + " tasks in the list.");
+            } else {
+                System.out.println("ERROR: ☹ OOPS!!! Invalid task number.");
+            }
+        } catch (DukeException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
+            System.out.println("Please enter command in the format: delete <task number>");
+        } catch (NumberFormatException e) {
+            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            System.out.println("Please enter command in the format: delete <task number>");
+        }
+    }
 
     public static void main(String[] args) {
         greet();
@@ -333,6 +375,10 @@ public static void main(String[] args) {
                             addEvent(tasks, parts);
                             break;
 
+                        case "delete":
+                            deleteTask(tasks, parts);
+                            break;
+
                         default:
                             echo(command);
                             throw new DukeException();

From 39957f7fff473ee0843d36d9c82639d767b6cded Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 20 Sep 2023 09:52:09 +0800
Subject: [PATCH 18/28] added level-7 increments

---
 src/main/java/Duke.java                | 107 +++++++++++++++++++++++++
 src/main/java/tasks/Deadline.java      |  19 ++++-
 src/main/java/tasks/DukeException.java |   2 +-
 src/main/java/tasks/Event.java         |  21 ++++-
 src/main/java/tasks/Task.java          |   4 +-
 src/main/java/tasks/Todo.java          |  17 +++-
 6 files changed, 165 insertions(+), 5 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 3af6f8151..0e48bdb57 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,6 +1,11 @@
 import java.util.ArrayList;
 import java.util.Scanner;
 
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.FileNotFoundException;
+
 import tasks.Deadline;
 import tasks.Event;
 import tasks.Task;
@@ -27,6 +32,97 @@ public class Duke {
             + COMMAND_MARK + " <task number> - marks the task as done\n"
             + COMMAND_UNMARK + " <task number> - marks the task as not done yet\n"
             + COMMAND_DELETE + " <task number> - deletes the task\n";
+
+    /*
+     * This method creates a file if it does not exist.
+     * @param f the file to be created
+     * @return true if the file is created successfully, false otherwise
+     * @throws IOException if the file cannot be created
+     */
+    private static boolean createFile(File f) {
+        try {
+            return f.createNewFile();
+        } catch (IOException e) {
+            System.out.println("Error: ☹ OOPS!!! Unable to create file.");
+            return false;
+        }
+    }
+
+    /*
+     * This method creates a data directory if it does not exist.
+     * @param f the file to be created
+     * @return true if the file is created successfully, false otherwise
+     */
+    private static void makeDataDir() {
+        File dataDirectory = new File("./data/");
+        if(!dataDirectory.exists()) {
+            dataDirectory.mkdir();
+        }
+    }
+
+    /*
+     * This method appends the task to the file.
+     * @param filePath the path of the file
+     * @param task the task to be appended to the file
+     * @throws IOException if the file cannot be written to
+     */
+    private static void appendToFile(String filePath, Task task) {
+        try {
+            FileWriter fw = new FileWriter(filePath, true);
+            fw.write(task.toData() + "\n");
+            fw.close();
+        } catch (IOException e) {
+            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
+        }
+    }
+
+    /*
+     * This method loads the data from the file.
+     * @param file the file to be loaded
+     * @param list the list of tasks
+     * @return the list of tasks
+     * @throws FileNotFoundException if the file cannot be found
+     */
+    private static ArrayList<Task> loadData(File file, ArrayList<Task> list) {
+        try {
+            Scanner s = new Scanner(file);
+            while (s.hasNext()) {
+                String taskData = s.nextLine();
+                String taskType = taskData.substring(0, 1);
+
+                switch(taskType) {
+                case "T":
+                    list.add(Todo.dataToTask(taskData.substring(4)));
+                    break;
+                
+                case "D":
+                    list.add(Deadline.dataToTask(taskData.substring(4)));
+                    break;
+                
+                case "E":
+                    list.add(Event.dataToTask(taskData.substring(4)));
+                    break;
+                }
+            }
+        } catch (FileNotFoundException e) {
+            System.out.println("Error: ☹ OOPS!!! File not found. Unable to load data.");
+        }
+        return list;
+    }
+
+
+    private static void writeAllToFile(ArrayList<Task> list, File f) {
+        try {
+            FileWriter fw = new FileWriter(f);
+            for(int i = 0; i < list.size(); i++) {
+                fw.write(list.get(i).toData() + "\n");
+            }
+            fw.close();
+        } catch (IOException e) {
+            
+            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
+        }
+    }
     /*
      * This method prints the greetings message when the user starts the program.
      */
@@ -290,6 +386,12 @@ public static void main(String[] args) {
 
         try (Scanner givenTask = new Scanner(System.in)) {
             ArrayList<Task> tasks = new ArrayList<>();
+            String filePath = "data/duke.txt";
+            makeDataDir();
+            File f = new File(filePath);
+            if(!createFile(f)){
+                tasks = loadData(f, tasks);
+            }
 
 
             while(true) {
@@ -315,22 +417,27 @@ public static void main(String[] args) {
 
                         case "mark":
                             markTask(tasks, parts);
+                            writeAllToFile(tasks, f);
                             break;
 
                         case "unmark":
                             unmarkTask(tasks, parts);
+                            writeAllToFile(tasks, f);
                             break;
 
                         case "todo":
                             addTodo(tasks, parts);
+                            appendToFile(filePath, tasks.get(tasks.size() - 1));
                             break;
 
                         case "deadline":
                             addDeadline(tasks, parts);
+                            appendToFile(filePath, tasks.get(tasks.size() - 1));
                             break;
 
                         case "event":
                             addEvent(tasks, parts);
+                            appendToFile(filePath, tasks.get(tasks.size() - 1));
                             break;
 
                         default:
diff --git a/src/main/java/tasks/Deadline.java b/src/main/java/tasks/Deadline.java
index 8ae6ef758..625009a12 100644
--- a/src/main/java/tasks/Deadline.java
+++ b/src/main/java/tasks/Deadline.java
@@ -1,6 +1,6 @@
 package tasks;
 
-import tasks.Task;
+//import tasks.Task;
 
 public class Deadline extends Task{
     protected String by;
@@ -17,6 +17,23 @@ public String getBy() {
         return this.by;
     }
 
+    public static Task dataToTask(String taskData) {
+        int firstSplitIndex = taskData.indexOf("|");
+        int secondSplitIndex = taskData.indexOf("|", firstSplitIndex + 1);
+        boolean isDone = taskData.substring(0, firstSplitIndex - 1).equals("1");
+        String desc = taskData.substring(firstSplitIndex + 2, secondSplitIndex - 1);
+        String by = taskData.substring(secondSplitIndex + 2);
+        Deadline newDeadline =  new Deadline(desc, by);
+        newDeadline.isDone = isDone;
+        return newDeadline;
+    }
+    
+    @Override
+    public String toData() {
+        String done = String.valueOf(this.isDone ? 1 : 0);
+        return "D | " + done + " | " + this.description + " | " + this.by;
+    }
+
     @Override
     public String toString() {
         return "[D]" + super.toString() + " (by: " + this.by + ")";
diff --git a/src/main/java/tasks/DukeException.java b/src/main/java/tasks/DukeException.java
index 0ef80686e..ee7b68482 100644
--- a/src/main/java/tasks/DukeException.java
+++ b/src/main/java/tasks/DukeException.java
@@ -1,6 +1,6 @@
 package tasks;
 
-import tasks.Task;
+//import tasks.Task;
 
 public class DukeException extends Exception{
     
diff --git a/src/main/java/tasks/Event.java b/src/main/java/tasks/Event.java
index 89a900516..123073192 100644
--- a/src/main/java/tasks/Event.java
+++ b/src/main/java/tasks/Event.java
@@ -1,6 +1,6 @@
 package tasks;
 
-import tasks.Task;
+//import tasks.Task;
 
 public class Event extends Task {
     protected String from;
@@ -20,8 +20,27 @@ public String getTo() {
         return this.to;
     }
 
+    @Override
+    public String toData() {
+        String done = String.valueOf(this.isDone ? 1 : 0);
+        return "E | " + done + " | " + this.description + " | " + this.from + " | " + this.to;
+    }
+
     @Override
     public String toString() {
         return "[E]" + super.toString() + "(from: " + this.from + " to: " + this.to + ")";
     }
+
+    public static Task dataToTask(String taskData) {
+        int firstSplitIndex = taskData.indexOf("|");
+        int secondSplitIndex = taskData.indexOf("|", firstSplitIndex + 1);
+        int thirdSplitIndex = taskData.indexOf("|", secondSplitIndex + 1);
+        boolean isDone = taskData.substring(0, firstSplitIndex - 1).equals("1");
+        String desc = taskData.substring(firstSplitIndex + 2, secondSplitIndex - 1);
+        String from = taskData.substring(secondSplitIndex + 2, thirdSplitIndex - 1);
+        String to = taskData.substring(thirdSplitIndex + 2);
+        Event newEvent =  new Event(desc, from, to);
+        newEvent.isDone = isDone;
+        return newEvent;
+    }
 }
diff --git a/src/main/java/tasks/Task.java b/src/main/java/tasks/Task.java
index 9bd9be9f1..0026a7237 100644
--- a/src/main/java/tasks/Task.java
+++ b/src/main/java/tasks/Task.java
@@ -1,6 +1,6 @@
 package tasks;
 
-public class Task {
+public abstract class Task {
     protected String description;
     protected boolean isDone;
 
@@ -29,4 +29,6 @@ public String toString() {
     public String getDescription() {
         return this.description;
     }
+
+    public abstract String toData();
 }
diff --git a/src/main/java/tasks/Todo.java b/src/main/java/tasks/Todo.java
index 3989a50f8..a45e07bfc 100644
--- a/src/main/java/tasks/Todo.java
+++ b/src/main/java/tasks/Todo.java
@@ -1,12 +1,27 @@
 package tasks;
 
-import tasks.Task;
+//import tasks.Task;
 
 public class Todo extends Task {
     public Todo (String description) {
         super(description);
     }
 
+    public static Task dataToTask(String taskData) {
+        int firstSplitIndex = taskData.indexOf("|");
+        boolean isDone = taskData.substring(0, firstSplitIndex - 1).equals("1");
+        String desc = taskData.substring(firstSplitIndex + 2);
+        Todo newTodo =  new Todo(desc);
+        newTodo.isDone = isDone;
+        return newTodo;
+    }
+
+    @Override
+    public String toData() {
+        String done = String.valueOf(this.isDone ? 1 : 0);
+        return "T | " + done + " | " + this.description;
+    }
+
     @Override
     public String toString() {
         return "[T]" + super.toString();

From 638e421542c83676371b719f265d5342fb4f659f Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Wed, 20 Sep 2023 10:06:39 +0800
Subject: [PATCH 19/28] edited code

---
 src/main/java/Duke.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 596d15208..36e528c8f 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -443,6 +443,7 @@ public static void main(String[] args) {
                     switch(commandType.toLowerCase()){
                         case "bye":
                             goodbye();
+                            System.exit(0);
                             break;
 
                         case "list":

From 9119029aa6fc6149d5542abc4ead941882627385 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 09:58:38 +0800
Subject: [PATCH 20/28] edited some code

---
 src/main/java/Duke.java | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 36e528c8f..3529acaed 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -481,6 +481,7 @@ public static void main(String[] args) {
 
                         case "delete":
                             deleteTask(tasks, parts);
+                            writeAllToFile(tasks, f);
                             break;
 
                         default:

From 85aaecb58360e0f5dab446220ff6e95e84cc235f Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 17:56:43 +0800
Subject: [PATCH 21/28] edited code, increment: A-MoreOOP done

---
 src/main/java/Duke.java                | 620 ++++++-------------------
 src/main/java/storage/Storage.java     |  92 ++++
 src/main/java/tasks/DukeException.java |  19 +-
 src/main/java/tasks/Parser.java        |  36 ++
 src/main/java/tasks/TaskList.java      |  56 +++
 src/main/java/ui/Ui.java               | 115 +++++
 6 files changed, 457 insertions(+), 481 deletions(-)
 create mode 100644 src/main/java/storage/Storage.java
 create mode 100644 src/main/java/tasks/Parser.java
 create mode 100644 src/main/java/tasks/TaskList.java
 create mode 100644 src/main/java/ui/Ui.java

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 3529acaed..044df81e4 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,499 +1,165 @@
-import java.util.ArrayList;
-import java.util.Scanner;
-
-import java.io.File;
-import java.io.FileWriter;
 import java.io.IOException;
-import java.io.FileNotFoundException;
 
+import storage.Storage;
 
 import tasks.Deadline;
 import tasks.Event;
 import tasks.Task;
 import tasks.Todo;
 import tasks.DukeException;
+import tasks.TaskList;
+import ui.Ui;
+import tasks.Parser;
 
 public class Duke {
-    public static final String lineDivider = "______________________________________________________________________";
-    private static final String COMMAND_EXIT = "bye";
-    private static final String COMMAND_LIST = "list";
-    private static final String COMMAND_TODO = "todo";
-    private static final String COMMAND_DEADLINE = "deadline";
-    private static final String COMMAND_EVENT = "event";
-    private static final String COMMAND_MARK = "mark";
-    private static final String COMMAND_UNMARK = "unmark";
-    private static final String COMMAND_DELETE = "delete";
-
-    private static final String HELP_MESSAGE = "\nHere are the list of commands that you can use:\n"
-            + COMMAND_EXIT + " - exits the program\n"
-            + COMMAND_LIST + " - lists all the tasks\n"
-            + COMMAND_TODO + " <description> - adds a ToDo task\n"
-            + COMMAND_DEADLINE + " <description> /by <time> - adds a Deadline task\n"
-            + COMMAND_EVENT + " <description> /from <time> /to <time> - adds an Event task\n"
-            + COMMAND_MARK + " <task number> - marks the task as done\n"
-            + COMMAND_UNMARK + " <task number> - marks the task as not done yet\n"
-            + COMMAND_DELETE + " <task number> - deletes the task\n";
-
-    /*
-     * This method creates a file if it does not exist.
-     * @param f the file to be created
-     * @return true if the file is created successfully, false otherwise
-     * @throws IOException if the file cannot be created
-     */
-    private static boolean createFile(File f) {
-        try {
-            return f.createNewFile();
-        } catch (IOException e) {
-            System.out.println("Error: ☹ OOPS!!! Unable to create file.");
-            return false;
-        }
-    }
-
-    /*
-     * This method creates a data directory if it does not exist.
-     * @param f the file to be created
-     * @return true if the file is created successfully, false otherwise
-     */
-    private static void makeDataDir() {
-        File dataDirectory = new File("./data/");
-        if(!dataDirectory.exists()) {
-            dataDirectory.mkdir();
-        }
-    }
-
-    /*
-     * This method appends the task to the file.
-     * @param filePath the path of the file
-     * @param task the task to be appended to the file
-     * @throws IOException if the file cannot be written to
-     */
-    private static void appendToFile(String filePath, Task task) {
-        try {
-            FileWriter fw = new FileWriter(filePath, true);
-            fw.write(task.toData() + "\n");
-            fw.close();
-        } catch (IOException e) {
-            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
-        }
-    }
-
-    /*
-     * This method loads the data from the file.
-     * @param file the file to be loaded
-     * @param list the list of tasks
-     * @return the list of tasks
-     * @throws FileNotFoundException if the file cannot be found
-     */
-    private static ArrayList<Task> loadData(File file, ArrayList<Task> list) {
-        try {
-            Scanner s = new Scanner(file);
-            while (s.hasNext()) {
-                String taskData = s.nextLine();
-                String taskType = taskData.substring(0, 1);
-
-                switch(taskType) {
-                case "T":
-                    list.add(Todo.dataToTask(taskData.substring(4)));
-                    break;
-                
-                case "D":
-                    list.add(Deadline.dataToTask(taskData.substring(4)));
-                    break;
-                
-                case "E":
-                    list.add(Event.dataToTask(taskData.substring(4)));
-                    break;
-                }
-            }
-        } catch (FileNotFoundException e) {
-            System.out.println("Error: ☹ OOPS!!! File not found. Unable to load data.");
-        }
-        return list;
-    }
-
-
-    private static void writeAllToFile(ArrayList<Task> list, File f) {
-        try {
-            FileWriter fw = new FileWriter(f);
-            for(int i = 0; i < list.size(); i++) {
-                fw.write(list.get(i).toData() + "\n");
-            }
-            fw.close();
-        } catch (IOException e) {
-            
-            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
-        }
-    }
-    /*
-     * This method prints the greetings message when the user starts the program.
-     */
-    public static void greet() {
-        String logo = "  ____                  \n"
-                + " |  _ \\  ___  _ __ ___  \n"
-                + " | | | |/ _ \\| '_ ` _ \\ \n"
-                + " | |_| | (_) | | | | | |\n"
-                + " |____/ \\___/|_| |_| |_|\n";
-        System.out.println("Hello from\n" + logo);
-        String greetings = lineDivider +
-                "\nHello! I'm Dom\n" +
-                "What can I do for you?\n" +
-                lineDivider;
-        System.out.println(greetings);
-    }
-
-    /*
-     * This method prints the goodbye message when the user exits the program.
-     */
-    public static void goodbye() {
-        echo("bye");
-        System.out.println("\nBye. Hope to see you again soon!");
-    }
-
-
-    /*
-     * This method prints the input message.
-     */
-    public static void echo(String input) {
-        System.out.println(input);
-    }
-
-    /*
-     * This method prints the list of tasks.
-     */
-    private static void listTasks(ArrayList<Task> tasks) {
-        if (tasks.isEmpty()) {
-            System.out.println("ERROR: ☹ OOPS!!! No tasks is available.");
-        } else {
-            System.out.println(" Here are the tasks in your list:");
-            for (int i = 0; i < tasks.size(); i++) {
-                Task task = tasks.get(i);
-
-                /*
-                 * checks if the task is a ToDo, Deadline or Event
-                 * prints the task type, status icon and description
-                 */
-                String taskType = task.getClass().equals(Todo.class) ? "[T]"
-                        : (task.getClass().equals(Deadline.class) ? "[D]" : "[E]");
-                String statusIcon = task.getStatusIcon();
-                String description = task.getDescription();
-
-                if (task.getClass().equals(Deadline.class)) {
-                    description += " (by: " + ((Deadline) task).getBy() + ")";
-                } else if (task.getClass().equals(Event.class)) {
-                    description += " (from: " + ((Event) task).getFrom() + " to: " + ((Event) task).getTo() + ")";
-                }
-                System.out.println(" " + (i + 1) + "." + taskType + statusIcon + " " + description);
-            }
-        }
-    }
-
-    /*
-     * This method marks the task as done.
-     *
-     * splits the command into two parts: command type and task number
-     * e.g. mark 1 will be split into "mark" and "1"
-     * the task number is then parsed into an integer
-     * the task number is then used to get the task from the list of tasks
-     * If the task number is invalid, it will print an error message.
-     * If the task number is valid, it will print the task that is marked as done.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the task number is empty or not an integer
-     * @throws NumberFormatException if the task number is not an integer
-     */
-    private static void markTask(ArrayList<Task> tasks, String[] parts) {
-        try {
-            if (parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-            int taskIndex = Integer.parseInt(parts[1]) - 1;
-            if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                Task task = tasks.get(taskIndex);
-                task.markAsDone(true);
-                System.out.println(" Nice! I've marked this task as done:\n" + "   " + task.getStatusIcon()
-                        + " " + task.getDescription());
-            } else {
-                System.out.println("ERROR: ☹ OOPS!!! Invalid task number.");
-            }
-        } catch (DukeException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
-            System.out.println("Please enter command in the format: mark <task number>");
-        } catch (NumberFormatException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
-            System.out.println("Please enter command in the format: mark <task number>");
-        }
-    }
-
-    /*
-     * This method marks the task as not done yet.
-     *
-     * splits the command into two parts: command type and task number
-     * e.g. unmark 1 will be split into "unmark" and "1"
-     * the task number is then parsed into an integer
-     * the task number is then used to get the task from the list of tasks
-     * If the task number is invalid, it will print an error message.
-     * If the task number is valid, it will print the task that is marked as not done yet.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the task number is empty or not an integer
-     * @throws NumberFormatException if the task number is not an integer
-     */
-    private static void unmarkTask(ArrayList<Task> tasks, String[] parts) {
-        try {
-            if (parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-
-            int taskIndex = Integer.parseInt(parts[1]) - 1;
-            if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                Task task = tasks.get(taskIndex);
-                task.markAsUndone(true);
-                System.out.println("OK, I've marked this task as not done yet:\n" + " "
-                        + task.getStatusIcon() + " " + task.getDescription());
-            } else {
-                System.out.println("Error: Invalid task number.");
-            }
-        } catch (DukeException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
-            System.out.println("Please enter command in the format: unmark <task number>");
-        } catch (NumberFormatException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
-            System.out.println("Please enter command in the format: unmark <task number>");
-        }
-    }
-
-
-    /*
-     * This method adds a ToDo task.
-     * splits the command into two parts: command type and description
-     * e.g. todo read book will be split into "todo" and "read book"
-     * the description is then used to create a new ToDo task
-     * the new ToDo task is then added to the list of tasks
-     * If the description is empty, it will print an error message.
-     * If the description is not empty, it will print the new ToDo task.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the description is empty
-     * @throws NumberFormatException if the task number is not an integer
-     *
-     */
-    private static void addTodo(ArrayList<Task> tasks, String[] parts) {
+    private static final String lineDivder = "____________________________________________________________";
+    private Storage storage;
+    private TaskList tasks;
+    private Ui ui;
+
+    public Duke(String filePath) {
+        ui = new Ui();
+        storage = new Storage(filePath);
         try {
-            if (parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-            tasks.add(new Todo(parts[1]));
-            System.out.println("Got it. I've added this task:");
-            System.out.println("  " + tasks.get(tasks.size() - 1));
-            System.out.println("Now you have " + tasks.size() + " tasks in the list.");
+            tasks = new TaskList(storage.load());
         } catch (DukeException e) {
-            System.out.println("☹ OOPS!!! The description of a todo cannot be empty.\n");
-            System.out.println("please enter command in the format: todo <description>");
+            ui.showErrorMsg(e.getMessage());
+            tasks = new TaskList();
         }
     }
 
-    /*
-     * This method adds a Deadline task.
-     * splits the command into two parts: command type and description
-     * e.g. deadline return book /by 2pm will be split into "deadline" and "return book /by 2pm"
-     * the description is then used to create a new Deadline task
-     * the new Deadline task is then added to the list of tasks
-     * If the description is empty, it will print an error message.
-     * If the description is not empty, it will print the new Deadline task.
-     * If the description is not empty, but the time is empty, it will print an error message.
-     * If the description is not empty, but the time is not empty, it will print the new Deadline task.
-     * If the description is not empty, but the time is not empty, but the time is invalid, it will print an error message.
-     * If the description is not empty, but the time is not empty, but the time is valid, it will print the new Deadline task.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the description is empty
-     *
-     *
-     */
-    private static void addDeadline(ArrayList<Task> tasks, String[] parts) {
-        try {
-            if (parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-            String[] deadlineParts = parts[1].split(" /by ");
-            if (deadlineParts.length == 2) {
-                String description = deadlineParts[0];
-                String by = deadlineParts[1].trim();
-                tasks.add(new Deadline(description, by));
-                System.out.println("Got it. I've added this task:");
-                System.out.println("  " + tasks.get(tasks.size() - 1));
-                System.out.println("Now you have " + tasks.size() + " tasks in the list.");
-            } else {
-                System.out.println("Invalid command.");
-            }
-        } catch (DukeException e) {
-            System.out.println("☹ OOPS!!! The description of a deadline cannot be empty.\n");
-            System.out.println("please enter command in the format: deadline <description> /by <time>");
-        }
-    }
-
-    /*
-     * This method adds an Event task.
-     * splits the command into two parts: command type and description
-     * e.g. event project meeting /from 2pm /to 4pm will be split into "event" and "project meeting /from 2pm /to 4pm"
-     * the description is then used to create a new Event task
-     * the new Event task is then added to the list of tasks
-     * If the description is empty, it will print an error message.
-     * If the description is not empty, it will print the new Event task.
-     * If the description is not empty, but the time is empty, it will print an error message.
-     * If the description is not empty, but the time is not empty, it will print the new Event task.
-     * If the description is not empty, but the time is not empty, but the time is invalid, it will print an error message.
-     * If the description is not empty, but the time is not empty, but the time is valid, it will print the new Event task.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the description is empty
-     *
-     */
-    private static void addEvent(ArrayList<Task> tasks, String[] parts) {
-        try {
-            if (parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-            String[] eventParts = parts[1].split(" /from ");
-            if (eventParts.length == 2) {
-                String description = eventParts[0];
-                String[] timeParts = eventParts[1].split(" /to ");
-                if (timeParts.length == 2) {
-                    String from = timeParts[0].trim();
-                    String to = timeParts[1].trim();
-                    tasks.add(new Event(description, from, to));
-                    System.out.println("Got it. I've added this task:");
-                    System.out.println("  " + tasks.get(tasks.size() - 1));
-                    System.out.println("Now you have " + tasks.size() + " tasks in the list.");
-                } else {
-                    System.out.println("Invalid command.");
+    public void run(){
+        ui.greet();
+        boolean isExit = false;
+        while (!isExit) {
+            try {
+                String fullCommand = ui.readCommand();
+                String action = Parser.parse(fullCommand);
+                String [] parts = action.split("-", 2);
+                switch(parts[0]) {
+                    case "exit" :
+                        isExit = true;
+                        ui.showLineDivider();
+                        break;
+                    
+                    case "list" :
+                        tasks.listTasks();
+                        ui.showLineDivider();
+                        break;
+                    
+                    case "markAsDone" :
+                        try{
+                            int doneIndex = Integer.parseInt(parts[1]) - 1;
+                            tasks.markTaskAsDone(doneIndex);
+                            ui.showUnmarkedTask(tasks.getTaskIndex(doneIndex));
+                            storage.save(tasks.getTasks());
+                        } catch (NumberFormatException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+                            ui.showErrorMsg("Please enter command in the format: mark <task number>");
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        } catch (IndexOutOfBoundsException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
+                        }
+                        ui.showLineDivider();
+                        break;
+                    
+                    case "unmark" :
+                        try{
+                            int undoneIndex = Integer.parseInt(parts[1]) -1;
+                            tasks.markTaskAsUndone(undoneIndex);
+                            ui.showUnmarkedTask(tasks.getTaskIndex(undoneIndex));
+                            storage.save(tasks.getTasks());
+                        } catch (NumberFormatException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+                            ui.showErrorMsg("Please enter command in the format: unmark <task number>");
+                        } catch (IndexOutOfBoundsException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        }
+                        ui.showLineDivider();
+                        break;
+
+                    case "delete":
+                        int deleteIndex = Integer.parseInt(parts[1]) - 1;
+                        if (deleteIndex < 0 || deleteIndex >= tasks.getTaskCount()) {
+                            throw new DukeException("☹ OOPS!!! Invalid task number.");
+                        }
+                        Task taskToDelete = tasks.getTaskIndex(deleteIndex);
+                        tasks.deleteTask(deleteIndex);
+                        try{
+                            storage.save(tasks.getTasks());
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        }
+                        ui.showDeletedTask(taskToDelete, tasks.getTaskCount());
+                        ui.showLineDivider();
+                        break;
+
+                    case "addTodo":
+                        if (parts[0].trim().isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.\n" + lineDivder);
+                        }
+                        Task newTodo = new Todo(parts[1]);
+                        tasks.addTask(newTodo);
+                        ui.showAddedTask(newTodo, tasks.getTaskCount());
+                        try{
+                            storage.save(tasks.getTasks());
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        }
+                        ui.showLineDivider();
+                        break;
+
+                    case "addDeadline":
+                        String[] deadlineParts = parts[1].split("/by", 2);
+                        if (deadlineParts.length < 2 || deadlineParts[1].trim().isEmpty() || deadlineParts[0].trim().isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of a deadline cannot be empty. \n" + lineDivder);
+                        }
+                        Task newDeadline = new Deadline(deadlineParts[0].trim(), deadlineParts[1].trim());
+                        tasks.addTask(newDeadline);
+                        ui.showAddedTask(newDeadline, tasks.getTaskCount());
+                        try{
+                            storage.save(tasks.getTasks());
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        }
+                        ui.showLineDivider();
+                        break;
+
+                        case "addEvent":
+                        String[] eventParts = parts[1].split("/from", 2);
+                        if (eventParts.length < 2 || eventParts[1].trim().isEmpty() || eventParts[0].trim().isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The description of an event cannot be empty.");
+                        }
+                        
+                        String[] fromToParts = eventParts[1].split("/to", 2);
+                        if (fromToParts.length < 2 || fromToParts[0].trim().isEmpty() || fromToParts[1].trim().isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The start or end time for an event cannot be empty.\n" + lineDivder);
+                        }
+                        
+                        Task newEvent = new Event(eventParts[0].trim(), fromToParts[0].trim(), fromToParts[1].trim());
+                        tasks.addTask(newEvent);
+                        ui.showAddedTask(newEvent, tasks.getTaskCount());
+                        try {
+                            storage.save(tasks.getTasks());
+                        } catch (IOException e) {
+                            System.out.println("An error occurred while saving tasks to the file.");
+                        }
+                        ui.showLineDivider();
+                        break;
+                    
+                    default:
+                        throw new DukeException("Unknown action");
                 }
-            } else {
-                System.out.println("Invalid command.");
-            }
-        } catch (DukeException e) {
-            System.out.println("☹ OOPS!!! The description of an event cannot be empty.\n");
-            System.out.println("please enter command in the format: event <description> /from <time> /to <time>");
-        }
-    }
-    /*
-     * This method deletes a task.
-     *
-     * splits the command into two parts: command type and task number
-     * e.g. delete 1 will be split into "delete" and "1"
-     * the task number is then parsed into an integer
-     * If the task number is invalid, it will print an error message.
-     * if the task number is valid, it will print the task that is deleted.
-     *
-     * @param tasks the list of tasks
-     * @param parts the command that is split into two parts
-     * @throws DukeException if the task number is empty or not an integer
-     * @throws NumberFormatException if the task number is not an integer
-     *
-     */
-    private static void deleteTask(ArrayList<Task> tasks, String[] parts) {
-        try {
-            if(parts.length < 2 || parts[1].isEmpty()) {
-                throw new DukeException();
-            }
-            int taskIndex = Integer.parseInt(parts[1]) - 1;
-            if (taskIndex >= 0 && taskIndex < tasks.size()) {
-                Task removeTask = tasks.remove(taskIndex);
-                System.out.println("Noted. I've removed this task:");
-                System.out.println("  " + removeTask);
-                System.out.println("Now you have " + tasks.size() + " tasks in the list.");
-            } else {
-                System.out.println("ERROR: ☹ OOPS!!! Invalid task number.");
+            } catch (DukeException e) {
+                ui.showError(e.getMessage());
             }
-        } catch (DukeException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
-            System.out.println("Please enter command in the format: delete <task number>");
-        } catch (NumberFormatException e) {
-            System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
-            System.out.println("Please enter command in the format: delete <task number>");
         }
+        ui.showGoodbye();
     }
-
     public static void main(String[] args) {
-        greet();
-
-        try (Scanner givenTask = new Scanner(System.in)) {
-            ArrayList<Task> tasks = new ArrayList<>();
-            String filePath = "data/duke.txt";
-            makeDataDir();
-            File f = new File(filePath);
-            if(!createFile(f)){
-                tasks = loadData(f, tasks);
-            }
-
-
-            while(true) {
-                String command = givenTask.nextLine().trim();
-                System.out.println(lineDivider);
-
-                String[] parts = command.split(" ", 2);
-                String commandType = parts.length > 0 ? parts[0] : "";
-
-                try{
-                    switch(commandType.toLowerCase()){
-                        case "bye":
-                            goodbye();
-                            System.exit(0);
-                            break;
-
-                        case "list":
-                            listTasks(tasks);
-                            break;
-
-                        case "help":
-                            System.out.println(HELP_MESSAGE);
-                            break;
-
-                        case "mark":
-                            markTask(tasks, parts);
-                            writeAllToFile(tasks, f);
-                            break;
-
-                        case "unmark":
-                            unmarkTask(tasks, parts);
-                            writeAllToFile(tasks, f);
-                            break;
-
-                        case "todo":
-                            addTodo(tasks, parts);
-                            appendToFile(filePath, tasks.get(tasks.size() - 1));
-                            break;
-
-                        case "deadline":
-                            addDeadline(tasks, parts);
-                            appendToFile(filePath, tasks.get(tasks.size() - 1));
-                            break;
-
-                        case "event":
-                            addEvent(tasks, parts);
-                            appendToFile(filePath, tasks.get(tasks.size() - 1));
-                            break;
-
-                        case "delete":
-                            deleteTask(tasks, parts);
-                            writeAllToFile(tasks, f);
-                            break;
-
-                        default:
-                            echo(command);
-                            throw new DukeException();
-                    }
-                } catch (DukeException e) {
-                    System.out.println("Error: ☹ OOPS!!! I'm sorry, but I don't know what that means :-(\n");
-                    System.out.println("If assistance is required, please type 'help' for more information.");
-                }
-                System.out.println(lineDivider);
-            }
-        }
+        new Duke("data/tasks.txt").run();
     }
 }
\ No newline at end of file
diff --git a/src/main/java/storage/Storage.java b/src/main/java/storage/Storage.java
new file mode 100644
index 000000000..69697fcc1
--- /dev/null
+++ b/src/main/java/storage/Storage.java
@@ -0,0 +1,92 @@
+package storage;
+
+import tasks.Task;
+import tasks.Todo;
+import tasks.Deadline;
+import tasks.Event;
+import tasks.DukeException;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Scanner;
+
+
+public class Storage {
+
+    private String filePath;
+
+    public Storage(String filePath) {
+        this.filePath = filePath;
+    }
+
+    public ArrayList<Task> load() throws DukeException {
+        File file = new File(filePath);
+        ArrayList<Task> tasks = new ArrayList<>();
+
+        try {
+            Scanner scanner = new Scanner(file);
+            while (scanner.hasNext()) {
+                String data = scanner.nextLine();
+                String[] parts = data.split(" \\| ");
+                
+                switch (parts[0]) {
+                    case "T":
+                        Todo todo = new Todo(parts[2]);
+                        if (parts[1].equals("1")) {
+                            todo.markAsDone(true);
+                        }
+                        tasks.add(todo);
+                        break;
+                    case "D":
+                        Deadline deadline = new Deadline(parts[2], parts[3]);
+                        if (parts[1].equals("1")) {
+                            deadline.markAsDone(true);
+                        }
+                        tasks.add(deadline);
+                        break;
+                    case "E":
+                        if (parts.length < 5) {
+                            throw new DukeException("Stored Event task format is incorrect");
+                        }
+                        Event event = new Event(parts[2], parts[3], parts[4]);
+                        if (parts[1].equals("1")) {
+                            event.markAsDone(true);
+                        }
+                        tasks.add(event);
+                        break;
+                    default:
+                        System.out.println("Invalid task type");
+                }
+            }
+            scanner.close();
+        } catch (IOException e) {
+            System.out.println("Error loading file");
+        }
+
+        return tasks;
+    }
+
+    public void save(ArrayList<Task> tasks) throws IOException {
+        FileWriter fw = new FileWriter(filePath);
+        for (Task task : tasks) {
+            fw.write(task.toData() + "\n");
+        }
+        fw.close();
+    }
+
+    // Other methods like createFile, loadData, writeAllToFile, appendToFile can remain largely unchanged
+    // ... existing methods ...
+
+    private static void appendToFile(String filePath, Task task) {
+        try {
+            FileWriter fw = new FileWriter(filePath, true);
+            fw.write(task.toData() + "\n");
+            fw.close();
+        } catch (IOException e) {
+            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
+        }
+    }
+}
diff --git a/src/main/java/tasks/DukeException.java b/src/main/java/tasks/DukeException.java
index ee7b68482..7d7e7bff8 100644
--- a/src/main/java/tasks/DukeException.java
+++ b/src/main/java/tasks/DukeException.java
@@ -1,8 +1,19 @@
 package tasks;
 
-//import tasks.Task;
+public class DukeException extends Exception {
+    public DukeException() {
+        super();
+    }
 
-public class DukeException extends Exception{
-    
-}
+    public DukeException(String message) {
+        super(message);
+    }
+
+    public DukeException(String message, Throwable cause) {
+        super(message, cause);
+    }
 
+    public DukeException(Throwable cause) {
+        super(cause);
+    }
+}
diff --git a/src/main/java/tasks/Parser.java b/src/main/java/tasks/Parser.java
new file mode 100644
index 000000000..37a66c95a
--- /dev/null
+++ b/src/main/java/tasks/Parser.java
@@ -0,0 +1,36 @@
+package tasks;
+
+public class Parser {
+
+    public static String parse(String fullCommand) throws DukeException {
+        String trimmedCommand = fullCommand.trim(); // Remove leading and trailing whitespaces
+        String commandLowerCase = trimmedCommand.toLowerCase(); // Convert command to lowercase for case-insensitive matching
+
+        if (commandLowerCase.equals("bye")) {
+            return "exit";
+        } else if (commandLowerCase.equals("list")) {
+            return "list";
+        } else if (commandLowerCase.startsWith("done ")) {
+            return "markAsDone-" + trimmedCommand.substring(5);
+        } else if (commandLowerCase.startsWith("delete")) {
+            if (commandLowerCase.length() <= 6 || commandLowerCase.substring(6).trim().isEmpty()) {
+                throw new DukeException("☹ OOPS!!! Please provide a task number to delete.");
+            }
+            return "delete-" + trimmedCommand.substring(7);
+        } else if (commandLowerCase.startsWith("todo")) {
+            if (commandLowerCase.length() <= 4 || commandLowerCase.substring(4).trim().isEmpty()) {
+                throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.");
+            }
+            return "addTodo-" + trimmedCommand.substring(5);
+        } else if (commandLowerCase.startsWith("deadline ")) {
+            // Additional parsing for deadline command
+            return "addDeadline-" + trimmedCommand.substring(9);
+        } else if (commandLowerCase.startsWith("event ")) {
+            // Additional parsing for event command
+            return "addEvent-" + trimmedCommand.substring(6);
+        } else {
+            throw new DukeException("Unknown command");
+        }
+    }
+}
+
diff --git a/src/main/java/tasks/TaskList.java b/src/main/java/tasks/TaskList.java
new file mode 100644
index 000000000..df39ce541
--- /dev/null
+++ b/src/main/java/tasks/TaskList.java
@@ -0,0 +1,56 @@
+package tasks;
+
+import java.util.ArrayList;
+
+public class TaskList {
+    private ArrayList<Task> tasks;
+
+    public TaskList() {
+        this.tasks = new ArrayList<>();
+    }
+
+    public TaskList(ArrayList<Task> tasks) {
+        this.tasks = tasks;
+    }
+
+    public void addTask(Task task) {
+        this.tasks.add(task);
+    }
+
+    public void deleteTask(int index) {
+        this.tasks.remove(index);
+    }
+
+    public Task getTaskIndex(int index) {
+        return this.tasks.get(index);
+    }
+
+    public int getTaskCount() {
+        return this.tasks.size();
+    }
+
+    public void markTaskAsDone(int index) {
+        Task task = tasks.get(index);
+        task.markAsDone(true);
+    }
+
+    public void markTaskAsUndone(int index) {
+        Task task = tasks.get(index);
+        task.markAsDone(false);
+    }
+
+    public void listTasks() {
+        if (tasks.size() == 0) {
+            System.out.println("ERROR: ☹ OOPS!!! No tasks is available.");
+            return;
+        }
+        System.out.println("Here are the tasks in your list:");
+        for (int i = 0; i < tasks.size(); i++) {
+            System.out.println((i + 1) + "." + tasks.get(i));
+        }
+    }
+
+    public ArrayList<Task> getTasks() {
+        return this.tasks;
+    }
+}
diff --git a/src/main/java/ui/Ui.java b/src/main/java/ui/Ui.java
new file mode 100644
index 000000000..3480fa80f
--- /dev/null
+++ b/src/main/java/ui/Ui.java
@@ -0,0 +1,115 @@
+package ui;
+
+import java.util.Scanner;
+import java.util.ArrayList;
+import tasks.Task;
+
+public class Ui {
+    private Scanner scanner;
+
+    private static final String lineDivider = "____________________________________________________________";
+
+    public Ui() {
+        this.scanner = new Scanner(System.in);
+    }
+
+    public static void greet() {
+        String logo = "  ____                  \n"
+                + " |  _ \\  ___  _ __ ___  \n"
+                + " | | | |/ _ \\| '_ ` _ \\ \n"
+                + " | |_| | (_) | | | | | |\n"
+                + " |____/ \\___/|_| |_| |_|\n";
+        System.out.println("Hello from\n" + logo);
+        String greetings = lineDivider +
+                "\nHello! I'm Dom\n" +
+                "What can I do for you?\n" +
+                lineDivider;
+        System.out.println(greetings);
+    }
+
+    public void goodbye() {
+        String goodbye = lineDivider +
+                "\nBye. Hope to see you again soon!\n" +
+                lineDivider;
+        System.out.println(goodbye);
+    }
+
+    public static void showLoadingError() {
+        System.out.println("Error loading file");
+    }
+
+    public void showErrorMsg(String errorMsg) {
+        System.out.println(errorMsg);
+    }
+
+    public String readCommand() {
+        return scanner.nextLine();
+    }
+
+    public void showLineDivider() {
+        System.out.println(lineDivider);
+    }
+
+    public void listTasks(ArrayList<Task> tasks) {
+        if (tasks.size() == 0) {
+            System.out.println("You have no tasks in your list");
+            return;
+        }
+        System.out.println("Here are the tasks in your list:");
+        for (int i = 0; i < tasks.size(); i++) {
+            System.out.println((i + 1) + "." + tasks.get(i));
+        }
+    }
+
+    public void showTaskMarked(Task task) {
+        System.out.println("OK, I've marked this task as done:\n" + " "
+                + task.getStatusIcon() + " " + task.getDescription());
+    }
+    
+
+    public void showUnmarkedTask(Task task) {
+        System.out.println(" Nice! I've marked this task as not done:\n" + "   " + task.getStatusIcon()
+        + " " + task.getDescription());
+    }
+
+    public void showInvalidTaskNumberError() {
+        System.out.println("Error: Invalid task number.");
+    }
+    
+    public void showEmptyTaskNumberError() {
+        System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
+        System.out.println("Please enter command in the format: unmark <task number>");
+    }
+    
+    public void showInvalidTaskNumberFormatError() {
+        System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
+        System.out.println("Please enter command in the format: unmark <task number>");
+    }
+
+    public void showAddedTask(Task task, int taskCount) {
+        System.out.println("Got it. I've added this task:");
+        System.out.println("  " + task);
+        System.out.println("Now you have " + taskCount + " tasks in the list.");
+    }
+
+    /**
+     * Displays a message to the user when a task is deleted.
+     * @param task The task that was deleted.
+     * @param taskCount The total number of tasks in the list after deletion.
+     */
+    public void showDeletedTask(Task task, int taskCount) {
+        System.out.println("Noted. I've removed this task:");
+        System.out.println("  " + task);
+        System.out.println("Now you have " + taskCount + " tasks in the list.");
+    }
+
+    public void showError(String errorMessage) {
+        System.out.println(errorMessage);
+    }
+
+    public void showGoodbye() {
+        System.out.println("Bye. Hope to see you again soon!");
+    }
+
+
+}

From 614e4d618706b42190cb44d6f236ed40ec1a853a Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 18:24:27 +0800
Subject: [PATCH 22/28] edited code

---
 src/main/java/Duke.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 044df81e4..6f4282254 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -98,7 +98,7 @@ public void run(){
                         break;
 
                     case "addTodo":
-                        if (parts[0].trim().isEmpty()) {
+                        if (parts[1].trim().isEmpty()) {
                             throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.\n" + lineDivder);
                         }
                         Task newTodo = new Todo(parts[1]);

From 23e63d4a7cdf585cf20c2b5e7d753e676293b950 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 18:33:10 +0800
Subject: [PATCH 23/28] Level-9 increment done

---
 src/main/java/Duke.java           | 16 +++++++++++++++-
 src/main/java/tasks/Parser.java   |  3 +++
 src/main/java/tasks/TaskList.java | 10 ++++++++++
 src/main/java/ui/Ui.java          |  8 +++++++-
 4 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 6f4282254..45a3b0030 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -1,4 +1,5 @@
 import java.io.IOException;
+import java.util.ArrayList;
 
 import storage.Storage;
 
@@ -149,7 +150,20 @@ public void run(){
                         }
                         ui.showLineDivider();
                         break;
-                    
+
+                    case "find":
+                        String keyword = parts[1].trim();
+                        if (keyword.isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! The keyword for find cannot be empty.\n" + lineDivder);
+                        }
+
+                        ArrayList<Task> foundTasks = tasks.findTasks(keyword);
+                        if (foundTasks.isEmpty()) {
+                            throw new DukeException("☹ OOPS!!! No matching tasks found with the given keyword.\n" + lineDivder);
+                        }
+                        ui.showFoundTasks(tasks.findTasks(keyword));
+                        ui.showLineDivider();
+                        break;
                     default:
                         throw new DukeException("Unknown action");
                 }
diff --git a/src/main/java/tasks/Parser.java b/src/main/java/tasks/Parser.java
index 37a66c95a..278b3c109 100644
--- a/src/main/java/tasks/Parser.java
+++ b/src/main/java/tasks/Parser.java
@@ -28,6 +28,9 @@ public static String parse(String fullCommand) throws DukeException {
         } else if (commandLowerCase.startsWith("event ")) {
             // Additional parsing for event command
             return "addEvent-" + trimmedCommand.substring(6);
+        } else if (commandLowerCase.startsWith("find ")) {
+            // Additional parsing for find command
+            return "find-" + trimmedCommand.substring(5);
         } else {
             throw new DukeException("Unknown command");
         }
diff --git a/src/main/java/tasks/TaskList.java b/src/main/java/tasks/TaskList.java
index df39ce541..3642ab9c9 100644
--- a/src/main/java/tasks/TaskList.java
+++ b/src/main/java/tasks/TaskList.java
@@ -53,4 +53,14 @@ public void listTasks() {
     public ArrayList<Task> getTasks() {
         return this.tasks;
     }
+
+    public ArrayList<Task> findTasks(String keyword) {
+        ArrayList<Task> foundTasks = new ArrayList<>();
+        for (Task task : tasks) {
+            if (task.getDescription().contains(keyword)) {
+                foundTasks.add(task);
+            }
+        }
+        return foundTasks;
+    }
 }
diff --git a/src/main/java/ui/Ui.java b/src/main/java/ui/Ui.java
index 3480fa80f..787b8319a 100644
--- a/src/main/java/ui/Ui.java
+++ b/src/main/java/ui/Ui.java
@@ -111,5 +111,11 @@ public void showGoodbye() {
         System.out.println("Bye. Hope to see you again soon!");
     }
 
-
+    public void showFoundTasks(ArrayList<Task> foundTasks) {
+        System.out.println(lineDivider);
+        System.out.println("Here are the matching tasks in your list:");
+        for (int i = 0; i < foundTasks.size(); i++) {
+            System.out.println((i + 1) + "." + foundTasks.get(i));
+        }
+    }
 }

From fe6c10ec61bcce74a87c008cc7405e565c64aa71 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 19:20:34 +0800
Subject: [PATCH 24/28] added javadoc

---
 src/main/java/Duke.java           | 15 ++++++
 src/main/java/tasks/Deadline.java | 33 ++++++++++--
 src/main/java/tasks/Event.java    | 38 +++++++++++++-
 src/main/java/tasks/Parser.java   |  7 +++
 src/main/java/tasks/Task.java     | 39 ++++++++++++++
 src/main/java/tasks/TaskList.java | 45 +++++++++++++++++
 src/main/java/tasks/Todo.java     | 23 +++++++--
 src/main/java/ui/Ui.java          | 84 +++++++++++++++++++++++++++++++
 8 files changed, 276 insertions(+), 8 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 45a3b0030..457530b80 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -12,12 +12,22 @@
 import ui.Ui;
 import tasks.Parser;
 
+
+/**
+ * Represents the main logic for the Duke application.
+ * Manages the initialization, execution, and storage of tasks.
+ */
 public class Duke {
     private static final String lineDivder = "____________________________________________________________";
     private Storage storage;
     private TaskList tasks;
     private Ui ui;
 
+   /**
+    * Initializes a new Duke instance with the given file path for data storage.
+    * 
+    * @param filePath The path of the file to store task data.
+    */
     public Duke(String filePath) {
         ui = new Ui();
         storage = new Storage(filePath);
@@ -173,6 +183,11 @@ public void run(){
         }
         ui.showGoodbye();
     }
+    /**
+     * The main entry point of the Duke application.
+     *
+     * @param args Command-line arguments.
+     */
     public static void main(String[] args) {
         new Duke("data/tasks.txt").run();
     }
diff --git a/src/main/java/tasks/Deadline.java b/src/main/java/tasks/Deadline.java
index 625009a12..4dbeea5ea 100644
--- a/src/main/java/tasks/Deadline.java
+++ b/src/main/java/tasks/Deadline.java
@@ -1,10 +1,17 @@
 package tasks;
 
-//import tasks.Task;
-
+/**
+ * Represents a 'Deadline' task in the Duke application.
+ */
 public class Deadline extends Task{
     protected String by;
-
+    
+    /*
+     * Initializes a new Deadline with the given description and deadline.
+     * 
+     * @param description The description of the deadline.
+     * @param by The deadline of the deadline.
+     */
     public Deadline(String description, String by) {
         super(description);
         if (description == null || description.trim().isEmpty()) {
@@ -13,10 +20,20 @@ public Deadline(String description, String by) {
         this.by = by;
     }
 
+    /*
+     * Returns the deadline of the deadline.
+     * 
+     * @return The deadline of the deadline.
+     */
     public String getBy() {
         return this.by;
     }
 
+    /*
+     * Converts the Deadline task object to a data representation for saving to a file.
+     * 
+     * @return The data representation of the Deadline task.
+     */
     public static Task dataToTask(String taskData) {
         int firstSplitIndex = taskData.indexOf("|");
         int secondSplitIndex = taskData.indexOf("|", firstSplitIndex + 1);
@@ -28,12 +45,22 @@ public static Task dataToTask(String taskData) {
         return newDeadline;
     }
     
+    /*
+     * Converts the Deadline task object to a data representation for saving to a file.
+     * 
+     * @return The data representation of the Deadline task.
+     */
     @Override
     public String toData() {
         String done = String.valueOf(this.isDone ? 1 : 0);
         return "D | " + done + " | " + this.description + " | " + this.by;
     }
 
+    /*
+     * Returns the string representation of the Deadline task.
+     * 
+     * @return The string representation of the Deadline task.
+     */
     @Override
     public String toString() {
         return "[D]" + super.toString() + " (by: " + this.by + ")";
diff --git a/src/main/java/tasks/Event.java b/src/main/java/tasks/Event.java
index 123073192..f31c315b8 100644
--- a/src/main/java/tasks/Event.java
+++ b/src/main/java/tasks/Event.java
@@ -1,36 +1,70 @@
 package tasks;
 
-//import tasks.Task;
-
+/**
+ * Represents an 'Event' task in the Duke application.
+ */
 public class Event extends Task {
     protected String from;
     protected String to;
 
+    /*
+     * Initializes a new Event with the given description, start time, and end time.
+     * 
+     * @param description The description of the event.
+     * @param from The start time of the event.
+     * @param to The end time of the event.
+     */
     public Event(String description, String from, String to) {
         super(description);
         this.from = from;
         this.to = to;
     }
 
+    /*
+     * Returns the start time of the event.
+     * 
+     * @return The start time of the event.
+     */
     public String getFrom() {
         return this.from;
     }
 
+    /*
+     * Returns the end time of the event.
+     * 
+     * @return The end time of the event.
+     */
     public String getTo() {
         return this.to;
     }
 
+    /*
+     * Converts the Event task object to a data representation for saving to a file.
+     * 
+     * @return The data representation of the Event task.
+     */
     @Override
     public String toData() {
         String done = String.valueOf(this.isDone ? 1 : 0);
         return "E | " + done + " | " + this.description + " | " + this.from + " | " + this.to;
     }
 
+    /*
+     * Returns the string representation of the Event task.
+     * 
+     * @return The string representation of the Event task.
+     */
     @Override
     public String toString() {
         return "[E]" + super.toString() + "(from: " + this.from + " to: " + this.to + ")";
     }
 
+    /*
+     * Returns a new Event task based on the given task data.
+     * 
+     * @param taskData The task data to be converted.
+     * @return The new Event task.
+     */
     public static Task dataToTask(String taskData) {
         int firstSplitIndex = taskData.indexOf("|");
         int secondSplitIndex = taskData.indexOf("|", firstSplitIndex + 1);
diff --git a/src/main/java/tasks/Parser.java b/src/main/java/tasks/Parser.java
index 278b3c109..2594783a2 100644
--- a/src/main/java/tasks/Parser.java
+++ b/src/main/java/tasks/Parser.java
@@ -1,6 +1,13 @@
 package tasks;
 
 public class Parser {
+    /**
+    * Parses the user command into actionable instructions.
+    * 
+    * @param fullCommand The entire command entered by the user.
+    * @return A string representation of the action to be taken.
+    * @throws DukeException If the command is invalid or incomplete.
+    */
 
     public static String parse(String fullCommand) throws DukeException {
         String trimmedCommand = fullCommand.trim(); // Remove leading and trailing whitespaces
diff --git a/src/main/java/tasks/Task.java b/src/main/java/tasks/Task.java
index 0026a7237..748851780 100644
--- a/src/main/java/tasks/Task.java
+++ b/src/main/java/tasks/Task.java
@@ -1,34 +1,73 @@
 package tasks;
 
+/**
+ * Represents a task in the Duke application.
+ */
 public abstract class Task {
     protected String description;
     protected boolean isDone;
 
 
+    /*
+     * Initializes a new Task with the given description.
+     * 
+     * @param description The description of the task.
+     * @param isDone The status of the task.
+     */
     public Task(String description) {
         this.description = description;
         this.isDone = false;
     }
 
+    /*
+     * Returns the status icon of the task.
+     * 
+     * @return The status icon of the task.
+     */
     public String getStatusIcon() {
         return (isDone ? "[X]" : "[ ]"); 
     }
 
+    /*
+     * Marks the task as done.
+     * 
+     * @param isDone The status of the task.
+     */
     public void markAsDone(boolean isDone) {
         this.isDone = true;
     }
     
+    /*
+     * Marks the task as undone.
+     * 
+     * @param isDone The status of the task.
+     */
     public void markAsUndone(boolean isDone) {
         this.isDone = false;
     }
 
+    /*
+     * Returns the string representation of the task.
+     * 
+     * @return The string representation of the task.
+     */
     public String toString() {
         return getStatusIcon() + " " + this.description;
     }
 
+    /*
+     * Returns the description of the task.
+     * 
+     * @return The description of the task.
+     */
     public String getDescription() {
         return this.description;
     }
 
+    /*
+     * Converts the task object to a data representation for saving to a file.
+     * 
+     * @return The data representation of the task.
+     */
     public abstract String toData();
 }
diff --git a/src/main/java/tasks/TaskList.java b/src/main/java/tasks/TaskList.java
index 3642ab9c9..50035f547 100644
--- a/src/main/java/tasks/TaskList.java
+++ b/src/main/java/tasks/TaskList.java
@@ -13,32 +13,66 @@ public TaskList(ArrayList<Task> tasks) {
         this.tasks = tasks;
     }
 
+    /**
+     * Adds a task to the list.
+     * 
+     * @param task The task to be added.
+     */
     public void addTask(Task task) {
         this.tasks.add(task);
     }
 
+    /**
+     * Removes a task from the list based on its index.
+     * 
+     * @param index The index of the task to be removed.
+     */
     public void deleteTask(int index) {
         this.tasks.remove(index);
     }
 
+    /**
+     * Returns the task at the specified index.
+     * 
+     * @param index The index of the task to be returned.
+     * @return The task at the specified index.
+     */
     public Task getTaskIndex(int index) {
         return this.tasks.get(index);
     }
 
+    /**
+     * Returns the number of tasks in the list.
+     * 
+     * @return The number of tasks in the list.
+     */
     public int getTaskCount() {
         return this.tasks.size();
     }
 
+    /**
+     * Marks a specified task as done.
+     *
+     * @param index The index of the task to be marked as done.
+     */
     public void markTaskAsDone(int index) {
         Task task = tasks.get(index);
         task.markAsDone(true);
     }
 
+    /**
+     * Marks a specified task as undone.
+     *
+     * @param index The index of the task to be marked as undone.
+     */
     public void markTaskAsUndone(int index) {
         Task task = tasks.get(index);
         task.markAsDone(false);
     }
 
+    /**
+     * Prints the list of tasks.
+     */
     public void listTasks() {
         if (tasks.size() == 0) {
             System.out.println("ERROR: ☹ OOPS!!! No tasks is available.");
@@ -50,10 +84,21 @@ public void listTasks() {
         }
     }
 
+    /**
+     * Returns the list of tasks.
+     * 
+     * @return The list of tasks.
+     */
     public ArrayList<Task> getTasks() {
         return this.tasks;
     }
 
+    /**
+     * Finds tasks that contain the specified keyword.
+     * 
+     * @param keyword The keyword to be searched for.
+     * @return The list of tasks that contain the specified keyword.
+     */
     public ArrayList<Task> findTasks(String keyword) {
         ArrayList<Task> foundTasks = new ArrayList<>();
         for (Task task : tasks) {
diff --git a/src/main/java/tasks/Todo.java b/src/main/java/tasks/Todo.java
index a45e07bfc..1ec2f0b58 100644
--- a/src/main/java/tasks/Todo.java
+++ b/src/main/java/tasks/Todo.java
@@ -1,12 +1,19 @@
 package tasks;
 
-//import tasks.Task;
-
+/**
+ * Represents a 'Todo' task in the Duke application.
+ */
 public class Todo extends Task {
     public Todo (String description) {
         super(description);
     }
 
+    /**
+     * Returns a new Todo task based on the given task data.
+     * 
+     * @param taskData The task data to be converted.
+     * @return The new Todo task.
+     */
     public static Task dataToTask(String taskData) {
         int firstSplitIndex = taskData.indexOf("|");
         boolean isDone = taskData.substring(0, firstSplitIndex - 1).equals("1");
@@ -16,12 +23,22 @@ public static Task dataToTask(String taskData) {
         return newTodo;
     }
 
+    /**
+     * Converts the Todo task object to a data representation for saving to a file.
+     * 
+     * @return The data representation of the Todo task.
+     */    
     @Override
     public String toData() {
         String done = String.valueOf(this.isDone ? 1 : 0);
         return "T | " + done + " | " + this.description;
     }
-
+    
+    /**
+     * Returns the string representation of the Todo task.
+     * 
+     * @return The string representation of the Todo task.
+     */
     @Override
     public String toString() {
         return "[T]" + super.toString();
diff --git a/src/main/java/ui/Ui.java b/src/main/java/ui/Ui.java
index 787b8319a..1d55b3c79 100644
--- a/src/main/java/ui/Ui.java
+++ b/src/main/java/ui/Ui.java
@@ -4,15 +4,25 @@
 import java.util.ArrayList;
 import tasks.Task;
 
+/**
+ * Represents the user interface of the Duke application.
+ */
+
 public class Ui {
     private Scanner scanner;
 
     private static final String lineDivider = "____________________________________________________________";
 
+    /**
+     * Initializes the Ui with a new Scanner instance.
+     */
     public Ui() {
         this.scanner = new Scanner(System.in);
     }
 
+    /**
+     * Displays the greeting message to the user when the application starts.
+     */
     public static void greet() {
         String logo = "  ____                  \n"
                 + " |  _ \\  ___  _ __ ___  \n"
@@ -27,6 +37,9 @@ public static void greet() {
         System.out.println(greetings);
     }
 
+    /**
+     * Displays a goodbye message to the user.
+     */
     public void goodbye() {
         String goodbye = lineDivider +
                 "\nBye. Hope to see you again soon!\n" +
@@ -34,22 +47,43 @@ public void goodbye() {
         System.out.println(goodbye);
     }
 
+    /**
+     * Displays an error message when there is a loading error.
+     */
     public static void showLoadingError() {
         System.out.println("Error loading file");
     }
 
+    /**
+     * Displays the specified error message to the user.
+     * 
+     * @param errorMsg The error message to display.
+     */
     public void showErrorMsg(String errorMsg) {
         System.out.println(errorMsg);
     }
 
+    /**
+     * Reads a command from the user.
+     * 
+     * @return The command entered by the user.
+     */
     public String readCommand() {
         return scanner.nextLine();
     }
 
+    /**
+     * Displays a line divider to the user.
+     */
     public void showLineDivider() {
         System.out.println(lineDivider);
     }
 
+    /**
+     * Lists all tasks currently in the task list.
+     * 
+     * @param tasks The list of tasks to be displayed.
+     */
     public void listTasks(ArrayList<Task> tasks) {
         if (tasks.size() == 0) {
             System.out.println("You have no tasks in your list");
@@ -61,31 +95,66 @@ public void listTasks(ArrayList<Task> tasks) {
         }
     }
 
+    /**
+     * Displays a message to the user when a task is marked as done.
+     * 
+     * @param task The task that was marked as done.
+     */
     public void showTaskMarked(Task task) {
         System.out.println("OK, I've marked this task as done:\n" + " "
                 + task.getStatusIcon() + " " + task.getDescription());
     }
     
 
+    /**
+     * Displays a message to the user when a task is marked as undone.
+     * 
+     * @param task The task that was marked as undone.
+     */
     public void showUnmarkedTask(Task task) {
         System.out.println(" Nice! I've marked this task as not done:\n" + "   " + task.getStatusIcon()
         + " " + task.getDescription());
     }
 
+    /**
+     * Displays a message to the user when a task is deleted.
+     * 
+     * @param task The task that was deleted.
+     * @param taskCount The total number of tasks in the list after deletion.
+     */
     public void showInvalidTaskNumberError() {
         System.out.println("Error: Invalid task number.");
     }
     
+    /*
+     * Displays a message to the user when a task is deleted.
+     * 
+     * @param task The task that was deleted.
+     * @param taskCount The total number of tasks in the list after deletion.
+     * 
+     */
     public void showEmptyTaskNumberError() {
         System.out.println("Error: ☹ OOPS!!! Task number cannot be empty\n");
         System.out.println("Please enter command in the format: unmark <task number>");
     }
     
+    /*
+     * Displays a message to the user when a task is deleted.
+     * 
+     * @param task The task that was deleted.
+     * @param taskCount The total number of tasks in the list after deletion.
+     * 
+     */
     public void showInvalidTaskNumberFormatError() {
         System.out.println("Error: ☹ OOPS!!! Task number must be an integer.\n");
         System.out.println("Please enter command in the format: unmark <task number>");
     }
 
+    /**
+     * Displays a message to the user when a task is added.
+     * @param task The task that was added.
+     * @param taskCount The total number of tasks in the list after addition.
+     */
     public void showAddedTask(Task task, int taskCount) {
         System.out.println("Got it. I've added this task:");
         System.out.println("  " + task);
@@ -103,14 +172,29 @@ public void showDeletedTask(Task task, int taskCount) {
         System.out.println("Now you have " + taskCount + " tasks in the list.");
     }
 
+    /**
+     * Displays a message to the user when a task is found.
+     * 
+     * @param task The task that was found.
+     */
     public void showError(String errorMessage) {
         System.out.println(errorMessage);
     }
 
+    /**
+     * Displays a message to the user when a task is found.
+     * 
+     * @param task The task that was found.
+     */
     public void showGoodbye() {
         System.out.println("Bye. Hope to see you again soon!");
     }
 
+    /**
+     * Displays a message to the user when a task is found.
+     * 
+     * @param task The task that was found.
+     */
     public void showFoundTasks(ArrayList<Task> foundTasks) {
         System.out.println(lineDivider);
         System.out.println("Here are the matching tasks in your list:");

From a99d632f67c365545ebeb1c82ba50278c6f04c66 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 20:06:44 +0800
Subject: [PATCH 25/28] improved code, added readme

---
 docs/README.md                     | 105 ++++++++++++++++++++++++-----
 src/main/java/Duke.java            |  27 +++++---
 src/main/java/storage/Storage.java |  14 ----
 src/main/java/tasks/Parser.java    |   5 +-
 src/main/java/tasks/Task.java      |  11 +--
 5 files changed, 110 insertions(+), 52 deletions(-)

diff --git a/docs/README.md b/docs/README.md
index 8077118eb..cf4eb8d5d 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -1,29 +1,104 @@
-# User Guide
+# DOM User Guide
+Dom is a desktop program to store a list of tasks for the user via a Command Line Interface(CLI)
+
+## Quick Start
+1. Ensure that you have JAVA '11' or above installed in your computer.
+2. Download the latest 'ip.jar' from [here](https://github.com/bljhty/ip/releases)
+3. Copy downloaded 'ip.jar' file to the desired home folder of your choice
+4. open a command terminal and 'cd' to the folder mentioned in ster 3
+5. type in the following to run the application
+
+```
+java -jar ip.jar
+```
+
+6. if successful, the following greeting should appear:
+```
+Hello from
+  ____                  
+ |  _ \  ___  _ __ ___  
+ | | | |/ _ \| '_ ` _ \ 
+ | |_| | (_) | | | | | |
+ |____/ \___/|_| |_| |_|
+
+____________________________________________________________
+Hello! I'm Dom
+What can I do for you?
+```
+7. Type in desired command to start using the program.
 
 ## Features 
+### Adding a todo task: `todo`
+Adds a task of type todo to the list.
+<br>Todo contains a description.
 
-### Feature-ABC
+Format: `todo DESCRIPTION`
+<br>Example: `todo read book`
 
-Description of the feature.
+### Adding an event: `event`
+Adds a task of type event to the list.
+<br>Event contains a description, from and to.
 
-### Feature-XYZ
+Format: `event DESCRIPTION /from FROM /to TO`
+<br>Example: `event CS2113 tutorial /from 4 April 2023 4pm /to 6pm`
 
-Description of the feature.
 
-## Usage
+### Adding a deadline: `deadline`
+Adds a task deadline to the list.
+<br>Deadline contains description and by.
 
-### `Keyword` - Describe action
+Format: `deadline DESCRIPTION /by BY`
+<br>Example: `deadline CS2113 iP /by 3 March 11.59pm`
 
-Describe the action and its outcome.
+### Viewing full list of tasks: `list`
+Shows a list of all tasks recorded in the list.
 
-Example of usage: 
+Format: `list`
 
-`keyword (optional arguments)`
+### Mark task as done: `mark`
+Marks task as done based on the task number indicated.
 
-Expected outcome:
+Format: `mark TASK_NUMBER`
+- TASK_NUMBER must be an integer that is within the list size
 
-Description of the outcome.
+Example: `mark 2`
 
-```
-expected output
-```
+### Mark task as not done: `unmark`
+Marks task as not done based on the task number indicated.
+
+Format: `unmark TASK_NUMBER`
+- TASK_NUMBER must be an integer that is within the list size
+
+Example: `unmark 3`
+
+### Delete task: `delete`
+Deletes the task based on the task number indicated.
+
+Format: `delete TASK_NUMBER`
+- TASK_NUMBER must be an integer that is within the list size
+
+Example: `delete 1`
+
+### Find task(s): `find`
+Searches the tasks in the list, returning the tasks containing the keyword in their description.
+
+Format: `find KEYWORD`
+<br>Example: `find CS2113`
+
+### Exiting DOM: `bye`
+Exits and closes the program.
+
+Format: `bye`
+
+## Command Summary
+| **Command** | **Format, Examples**                                                                                 |
+|-------------|------------------------------------------------------------------------------------------------------|
+| todo        | `todo DESCRIPTION`<br>e.g. `todo read book`                                                          |
+| event       | `event DESCRIPTION /from FROM /to TO`<br>e.g. `event CS2113 tutorial /from 4 April 2023 4pm /to 6pm` |
+| deadline    | `deadline DESCRIPTION /by BY`<br>e.g. `deadline CS2113 iP /by 3 March 11.59pm`                       |
+| list        | `list`                                                                                               |
+| mark        | `mark TASK_NUMBER`<br>e.g. `mark 2`                                                                  |
+| unmark      | `unmark TASK_NUMBER`<br>e.g. `unmark 3`                                                              |
+| delete      | `delete TASK_NUMBER`<br>e.g. `delete 1`                                                              |
+| find        | `find KEYWORD`<br>e.g. `find CS2113`                                                                 |
+| bye         | `bye`                                                                                                |
diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 457530b80..57dad3fcb 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -40,7 +40,7 @@ public Duke(String filePath) {
     }
 
     public void run(){
-        ui.greet();
+        Ui.greet();
         boolean isExit = false;
         while (!isExit) {
             try {
@@ -75,10 +75,10 @@ public void run(){
                         ui.showLineDivider();
                         break;
                     
-                    case "unmark" :
+                    case "markAsNotDone" :
                         try{
                             int undoneIndex = Integer.parseInt(parts[1]) -1;
-                            tasks.markTaskAsUndone(undoneIndex);
+                            tasks.getTaskIndex(undoneIndex).markAsDone(false);
                             ui.showUnmarkedTask(tasks.getTaskIndex(undoneIndex));
                             storage.save(tasks.getTasks());
                         } catch (NumberFormatException e) {
@@ -93,18 +93,23 @@ public void run(){
                         break;
 
                     case "delete":
-                        int deleteIndex = Integer.parseInt(parts[1]) - 1;
-                        if (deleteIndex < 0 || deleteIndex >= tasks.getTaskCount()) {
-                            throw new DukeException("☹ OOPS!!! Invalid task number.");
-                        }
-                        Task taskToDelete = tasks.getTaskIndex(deleteIndex);
-                        tasks.deleteTask(deleteIndex);
-                        try{
+                        try {
+                            int deleteIndex = Integer.parseInt(parts[1]) - 1;
+                            if (deleteIndex < 0 || deleteIndex >= tasks.getTaskCount()) {
+                                throw new DukeException("☹ OOPS!!! Invalid task number.");
+                            }
+                            Task taskToDelete = tasks.getTaskIndex(deleteIndex);
+                            tasks.deleteTask(deleteIndex);
                             storage.save(tasks.getTasks());
+                            ui.showDeletedTask(taskToDelete, tasks.getTaskCount());
                         } catch (IOException e) {
                             System.out.println("An error occurred while saving tasks to the file.");
+                        } catch (NumberFormatException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+                            ui.showErrorMsg("Please enter command in the format: delete <task number>");
+                        } catch (IndexOutOfBoundsException e) {
+                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number." + lineDivder);
                         }
-                        ui.showDeletedTask(taskToDelete, tasks.getTaskCount());
                         ui.showLineDivider();
                         break;
 
diff --git a/src/main/java/storage/Storage.java b/src/main/java/storage/Storage.java
index 69697fcc1..747f7ff64 100644
--- a/src/main/java/storage/Storage.java
+++ b/src/main/java/storage/Storage.java
@@ -7,7 +7,6 @@
 import tasks.DukeException;
 
 import java.io.File;
-import java.io.FileNotFoundException;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -76,17 +75,4 @@ public void save(ArrayList<Task> tasks) throws IOException {
         }
         fw.close();
     }
-
-    // Other methods like createFile, loadData, writeAllToFile, appendToFile can remain largely unchanged
-    // ... existing methods ...
-
-    private static void appendToFile(String filePath, Task task) {
-        try {
-            FileWriter fw = new FileWriter(filePath, true);
-            fw.write(task.toData() + "\n");
-            fw.close();
-        } catch (IOException e) {
-            System.out.println("Error: ☹ OOPS!!! Unable to write to file.");
-        }
-    }
 }
diff --git a/src/main/java/tasks/Parser.java b/src/main/java/tasks/Parser.java
index 2594783a2..f046de358 100644
--- a/src/main/java/tasks/Parser.java
+++ b/src/main/java/tasks/Parser.java
@@ -17,8 +17,10 @@ public static String parse(String fullCommand) throws DukeException {
             return "exit";
         } else if (commandLowerCase.equals("list")) {
             return "list";
-        } else if (commandLowerCase.startsWith("done ")) {
+        } else if (commandLowerCase.startsWith("mark ")) {
             return "markAsDone-" + trimmedCommand.substring(5);
+        } else if (commandLowerCase.startsWith("unmark ")) {
+            return "markAsNotDone-" + trimmedCommand.substring(7);
         } else if (commandLowerCase.startsWith("delete")) {
             if (commandLowerCase.length() <= 6 || commandLowerCase.substring(6).trim().isEmpty()) {
                 throw new DukeException("☹ OOPS!!! Please provide a task number to delete.");
@@ -43,4 +45,3 @@ public static String parse(String fullCommand) throws DukeException {
         }
     }
 }
-
diff --git a/src/main/java/tasks/Task.java b/src/main/java/tasks/Task.java
index 748851780..913662d31 100644
--- a/src/main/java/tasks/Task.java
+++ b/src/main/java/tasks/Task.java
@@ -34,18 +34,9 @@ public String getStatusIcon() {
      * @param isDone The status of the task.
      */
     public void markAsDone(boolean isDone) {
-        this.isDone = true;
+        this.isDone = isDone;
     }
     
-    /*
-     * Marks the task as undone.
-     * 
-     * @param isDone The status of the task.
-     */
-    public void markAsUndone(boolean isDone) {
-        this.isDone = false;
-    }
-
     /*
      * Returns the string representation of the task.
      * 

From 7a6474b0c747104f2c317253bc073b0fd3cc91f5 Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 20:11:10 +0800
Subject: [PATCH 26/28] added more javaDoc

---
 src/main/java/storage/Storage.java     | 21 ++++++++++++++++++++-
 src/main/java/tasks/Deadline.java      |  2 ++
 src/main/java/tasks/DukeException.java |  3 +++
 src/main/java/tasks/Parser.java        |  4 ++++
 src/main/java/tasks/TaskList.java      | 11 +++++++++++
 5 files changed, 40 insertions(+), 1 deletion(-)

diff --git a/src/main/java/storage/Storage.java b/src/main/java/storage/Storage.java
index 747f7ff64..930aeea4a 100644
--- a/src/main/java/storage/Storage.java
+++ b/src/main/java/storage/Storage.java
@@ -12,15 +12,28 @@
 import java.util.ArrayList;
 import java.util.Scanner;
 
-
+/**
+ * Represents the storage of tasks.
+ */
 public class Storage {
 
     private String filePath;
 
+    /**
+     * Initializes a new Storage instance with the given file path.
+     * 
+     * @param filePath The path of the file to store task data.
+     */
     public Storage(String filePath) {
         this.filePath = filePath;
     }
 
+    /**
+     * Loads the tasks from the file.
+     * 
+     * @return The list of tasks.
+     * @throws DukeException If the file is not found or the data format is incorrect.
+     */
     public ArrayList<Task> load() throws DukeException {
         File file = new File(filePath);
         ArrayList<Task> tasks = new ArrayList<>();
@@ -68,6 +81,12 @@ public ArrayList<Task> load() throws DukeException {
         return tasks;
     }
 
+    /**
+     * Saves the tasks to the file.
+     * 
+     * @param tasks The list of tasks to be saved.
+     * @throws IOException If there is an error writing to the file.
+     */
     public void save(ArrayList<Task> tasks) throws IOException {
         FileWriter fw = new FileWriter(filePath);
         for (Task task : tasks) {
diff --git a/src/main/java/tasks/Deadline.java b/src/main/java/tasks/Deadline.java
index 4dbeea5ea..6d9d7afe8 100644
--- a/src/main/java/tasks/Deadline.java
+++ b/src/main/java/tasks/Deadline.java
@@ -2,6 +2,8 @@
 
 /**
  * Represents a 'Deadline' task in the Duke application.
+ * 
+ * @see Task
  */
 public class Deadline extends Task{
     protected String by;
diff --git a/src/main/java/tasks/DukeException.java b/src/main/java/tasks/DukeException.java
index 7d7e7bff8..8f1089040 100644
--- a/src/main/java/tasks/DukeException.java
+++ b/src/main/java/tasks/DukeException.java
@@ -1,5 +1,8 @@
 package tasks;
 
+/**
+ * Represents an exception that is thrown when an error occurs in the Duke application.
+ */
 public class DukeException extends Exception {
     public DukeException() {
         super();
diff --git a/src/main/java/tasks/Parser.java b/src/main/java/tasks/Parser.java
index f046de358..ac6ea7905 100644
--- a/src/main/java/tasks/Parser.java
+++ b/src/main/java/tasks/Parser.java
@@ -1,5 +1,9 @@
 package tasks;
 
+/**
+ * Represents a parser that parses user commands.
+ */
+
 public class Parser {
     /**
     * Parses the user command into actionable instructions.
diff --git a/src/main/java/tasks/TaskList.java b/src/main/java/tasks/TaskList.java
index 50035f547..dfbcda51f 100644
--- a/src/main/java/tasks/TaskList.java
+++ b/src/main/java/tasks/TaskList.java
@@ -2,13 +2,24 @@
 
 import java.util.ArrayList;
 
+/**
+ * Represents a list of tasks.
+ */
 public class TaskList {
     private ArrayList<Task> tasks;
 
+    /**
+     * Initializes a new TaskList instance with an empty list of tasks.
+     */
     public TaskList() {
         this.tasks = new ArrayList<>();
     }
 
+    /**
+     * Initializes a new TaskList instance with the specified list of tasks.
+     * 
+     * @param tasks The list of tasks.
+     */
     public TaskList(ArrayList<Task> tasks) {
         this.tasks = tasks;
     }

From 1f207655560cd6c1614d236e7aaa68cc4569780b Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Sat, 30 Sep 2023 20:15:05 +0800
Subject: [PATCH 27/28] added changes to userguide

---
 docs/README.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/README.md b/docs/README.md
index cf4eb8d5d..08eea6b9b 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -90,6 +90,10 @@ Exits and closes the program.
 
 Format: `bye`
 
+## FAQ
+**Q**: Can I edit the file manually from the save.txt file?
+<br>**A**: It is not advised to do so, as formatting of the save.txt file incorrectly will cause the program to crash.
+
 ## Command Summary
 | **Command** | **Format, Examples**                                                                                 |
 |-------------|------------------------------------------------------------------------------------------------------|

From 4814f11c5461a30d7929a4d833b569ac375f286a Mon Sep 17 00:00:00 2001
From: Bryan Lee <e0725090@u.nus.edu>
Date: Tue, 3 Oct 2023 23:35:28 +0800
Subject: [PATCH 28/28] refactored code and make changes to code

---
 src/main/java/Duke.java | 339 +++++++++++++++++++++++++---------------
 1 file changed, 212 insertions(+), 127 deletions(-)

diff --git a/src/main/java/Duke.java b/src/main/java/Duke.java
index 57dad3fcb..125c584ce 100644
--- a/src/main/java/Duke.java
+++ b/src/main/java/Duke.java
@@ -18,16 +18,18 @@
  * Manages the initialization, execution, and storage of tasks.
  */
 public class Duke {
-    private static final String lineDivder = "____________________________________________________________";
+    private static final String lineDivider = "____________________________________________________________";
     private Storage storage;
     private TaskList tasks;
     private Ui ui;
 
-   /**
-    * Initializes a new Duke instance with the given file path for data storage.
-    * 
-    * @param filePath The path of the file to store task data.
-    */
+    /*
+     * Initializes a Duke object with the given file path.
+     * 
+     * @param filePath The file path to the file containing the tasks.
+     * @throws DukeException If an error occurs while loading the tasks from the file.
+     * 
+     */
     public Duke(String filePath) {
         ui = new Ui();
         storage = new Storage(filePath);
@@ -39,145 +41,48 @@ public Duke(String filePath) {
         }
     }
 
-    public void run(){
+    /*
+     * Runs the Duke application.
+     * 
+     * @throws DukeException If an error occurs while running the application.
+     */
+    public void run() {
         Ui.greet();
         boolean isExit = false;
         while (!isExit) {
             try {
                 String fullCommand = ui.readCommand();
                 String action = Parser.parse(fullCommand);
-                String [] parts = action.split("-", 2);
+                String[] parts = action.split("-", 2);
                 switch(parts[0]) {
-                    case "exit" :
+                    case "exit":
                         isExit = true;
                         ui.showLineDivider();
                         break;
-                    
-                    case "list" :
+                    case "list":
                         tasks.listTasks();
                         ui.showLineDivider();
                         break;
-                    
-                    case "markAsDone" :
-                        try{
-                            int doneIndex = Integer.parseInt(parts[1]) - 1;
-                            tasks.markTaskAsDone(doneIndex);
-                            ui.showUnmarkedTask(tasks.getTaskIndex(doneIndex));
-                            storage.save(tasks.getTasks());
-                        } catch (NumberFormatException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
-                            ui.showErrorMsg("Please enter command in the format: mark <task number>");
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        } catch (IndexOutOfBoundsException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
-                        }
-                        ui.showLineDivider();
+                    case "markAsDone":
+                        handleMarkAsDone(parts[1]);
                         break;
-                    
-                    case "markAsNotDone" :
-                        try{
-                            int undoneIndex = Integer.parseInt(parts[1]) -1;
-                            tasks.getTaskIndex(undoneIndex).markAsDone(false);
-                            ui.showUnmarkedTask(tasks.getTaskIndex(undoneIndex));
-                            storage.save(tasks.getTasks());
-                        } catch (NumberFormatException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
-                            ui.showErrorMsg("Please enter command in the format: unmark <task number>");
-                        } catch (IndexOutOfBoundsException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        }
-                        ui.showLineDivider();
+                    case "markAsNotDone":
+                        handleMarkAsNotDone(parts[1]);
                         break;
-
                     case "delete":
-                        try {
-                            int deleteIndex = Integer.parseInt(parts[1]) - 1;
-                            if (deleteIndex < 0 || deleteIndex >= tasks.getTaskCount()) {
-                                throw new DukeException("☹ OOPS!!! Invalid task number.");
-                            }
-                            Task taskToDelete = tasks.getTaskIndex(deleteIndex);
-                            tasks.deleteTask(deleteIndex);
-                            storage.save(tasks.getTasks());
-                            ui.showDeletedTask(taskToDelete, tasks.getTaskCount());
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        } catch (NumberFormatException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
-                            ui.showErrorMsg("Please enter command in the format: delete <task number>");
-                        } catch (IndexOutOfBoundsException e) {
-                            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number." + lineDivder);
-                        }
-                        ui.showLineDivider();
+                        handleDelete(parts[1]);
                         break;
-
                     case "addTodo":
-                        if (parts[1].trim().isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of a todo cannot be empty.\n" + lineDivder);
-                        }
-                        Task newTodo = new Todo(parts[1]);
-                        tasks.addTask(newTodo);
-                        ui.showAddedTask(newTodo, tasks.getTaskCount());
-                        try{
-                            storage.save(tasks.getTasks());
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        }
-                        ui.showLineDivider();
+                        handleAddTodo(parts[1]);
                         break;
-
                     case "addDeadline":
-                        String[] deadlineParts = parts[1].split("/by", 2);
-                        if (deadlineParts.length < 2 || deadlineParts[1].trim().isEmpty() || deadlineParts[0].trim().isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of a deadline cannot be empty. \n" + lineDivder);
-                        }
-                        Task newDeadline = new Deadline(deadlineParts[0].trim(), deadlineParts[1].trim());
-                        tasks.addTask(newDeadline);
-                        ui.showAddedTask(newDeadline, tasks.getTaskCount());
-                        try{
-                            storage.save(tasks.getTasks());
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        }
-                        ui.showLineDivider();
+                        handleAddDeadline(parts[1]);
                         break;
-
-                        case "addEvent":
-                        String[] eventParts = parts[1].split("/from", 2);
-                        if (eventParts.length < 2 || eventParts[1].trim().isEmpty() || eventParts[0].trim().isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The description of an event cannot be empty.");
-                        }
-                        
-                        String[] fromToParts = eventParts[1].split("/to", 2);
-                        if (fromToParts.length < 2 || fromToParts[0].trim().isEmpty() || fromToParts[1].trim().isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The start or end time for an event cannot be empty.\n" + lineDivder);
-                        }
-                        
-                        Task newEvent = new Event(eventParts[0].trim(), fromToParts[0].trim(), fromToParts[1].trim());
-                        tasks.addTask(newEvent);
-                        ui.showAddedTask(newEvent, tasks.getTaskCount());
-                        try {
-                            storage.save(tasks.getTasks());
-                        } catch (IOException e) {
-                            System.out.println("An error occurred while saving tasks to the file.");
-                        }
-                        ui.showLineDivider();
+                    case "addEvent":
+                        handleAddEvent(parts[1]);
                         break;
-
                     case "find":
-                        String keyword = parts[1].trim();
-                        if (keyword.isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! The keyword for find cannot be empty.\n" + lineDivder);
-                        }
-
-                        ArrayList<Task> foundTasks = tasks.findTasks(keyword);
-                        if (foundTasks.isEmpty()) {
-                            throw new DukeException("☹ OOPS!!! No matching tasks found with the given keyword.\n" + lineDivder);
-                        }
-                        ui.showFoundTasks(tasks.findTasks(keyword));
-                        ui.showLineDivider();
+                        handleFind(parts[1]);
                         break;
                     default:
                         throw new DukeException("Unknown action");
@@ -188,12 +93,192 @@ public void run(){
         }
         ui.showGoodbye();
     }
-    /**
-     * The main entry point of the Duke application.
-     *
-     * @param args Command-line arguments.
+
+    /*
+     * Handles the markAsDone command.
+     * also checks if the task number is valid.
+     * 
+     * @param part The part of the command after the markAsDone keyword.
+     * @throws DukeException If an error occurs while marking the task as done.
+     */
+    private void handleMarkAsDone(String part) {
+        try {
+            int doneIndex = Integer.parseInt(part) - 1;
+            tasks.markTaskAsDone(doneIndex);
+            ui.showUnmarkedTask(tasks.getTaskIndex(doneIndex));
+            storage.save(tasks.getTasks());
+        } catch (NumberFormatException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            ui.showErrorMsg("Please enter command in the format: mark <task number>");
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        } catch (IndexOutOfBoundsException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the markAsNotDone command.
+     * also checks if the task number is valid.
+     * 
+     * @param part The part of the command after the markAsNotDone keyword.
+     * @throws DukeException If an error occurs while marking the task as not done.
+     * @throws IOException If an error occurs while saving the tasks to the file.
+     * @throws IndexOutOfBoundsException If the task number is invalid.
+     */
+    private void handleMarkAsNotDone(String part) {
+        try {
+            int undoneIndex = Integer.parseInt(part) - 1;
+            tasks.getTaskIndex(undoneIndex).markAsDone(false);
+            ui.showUnmarkedTask(tasks.getTaskIndex(undoneIndex));
+            storage.save(tasks.getTasks());
+        } catch (NumberFormatException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            ui.showErrorMsg("Please enter command in the format: unmark <task number>");
+        } catch (IndexOutOfBoundsException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the delete command.
+     * also checks if the task number is valid.
+     * 
+     * @param part The part of the command after the delete keyword.
+     * @throws DukeException If an error occurs while deleting the task.
+     * @throws IOException If an error occurs while saving the tasks to the file.
+     * @throws IndexOutOfBoundsException If the task number is invalid.
+     * @throws NumberFormatException If the task number is not an integer.q
+     */
+    private void handleDelete(String part) {
+        try {
+            int deleteIndex = Integer.parseInt(part) - 1;
+            if (deleteIndex < 0 || deleteIndex >= tasks.getTaskCount()) {
+                System.out.println("☹ OOPS!!! Invalid task number.");
+            }
+            Task taskToDelete = tasks.getTaskIndex(deleteIndex);
+            tasks.deleteTask(deleteIndex);
+            storage.save(tasks.getTasks());
+            ui.showDeletedTask(taskToDelete, tasks.getTaskCount());
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        } catch (NumberFormatException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Task number must be an integer.\n");
+            ui.showErrorMsg("Please enter command in the format: delete <task number>");
+        } catch (IndexOutOfBoundsException e) {
+            ui.showErrorMsg("Error: ☹ OOPS!!! Invalid task number.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the addTodo command.
+     * checks if the description is empty.
+     * 
+     * @param part The part of the command after the addTodo keyword.
+     * @throws DukeException If an error occurs while adding the todo.
+     * @throws IOException If an error occurs while saving the tasks to the file. 
+     */
+    private void handleAddTodo(String part) {
+        if (part.trim().isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! The description of a todo cannot be empty.\n" + lineDivider);
+            return;
+        }
+        Task newTodo = new Todo(part);
+        tasks.addTask(newTodo);
+        ui.showAddedTask(newTodo, tasks.getTaskCount());
+        try {
+            storage.save(tasks.getTasks());
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the addDeadline command.
+     * checks if description or deadline is empty.
+     * 
+     * @param part The part of the command after the addDeadline keyword.
+     * @throws DukeException If an error occurs while adding the deadline.
+     * @throws IOException If an error occurs while saving the tasks to the file.
+     */
+    private void handleAddDeadline(String part) {
+        String[] deadlineParts = part.split("/by", 2);
+        if (deadlineParts.length < 2 || deadlineParts[1].trim().isEmpty() || deadlineParts[0].trim().isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! The description of a deadline cannot be empty. \n" + lineDivider);
+            return;
+        }
+        Task newDeadline = new Deadline(deadlineParts[0].trim(), deadlineParts[1].trim());
+        tasks.addTask(newDeadline);
+        ui.showAddedTask(newDeadline, tasks.getTaskCount());
+        try {
+            storage.save(tasks.getTasks());
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the addEvent command.
+     * checks if description, start time or end time is empty.
+     * 
+     * @param part The part of the command after the addEvent keyword.
+     * @throws DukeException If an error occurs while adding the event.
+     */
+    private void handleAddEvent(String part) {
+        String[] eventParts = part.split("/from", 2);
+        if (eventParts.length < 2 || eventParts[1].trim().isEmpty() || eventParts[0].trim().isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! The description of an event cannot be empty.\n" + lineDivider);
+            return;
+        }
+        
+        String[] fromToParts = eventParts[1].split("/to", 2);
+        if (fromToParts.length < 2 || fromToParts[0].trim().isEmpty() || fromToParts[1].trim().isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! The start or end time for an event cannot be empty.\n" + lineDivider);
+            return;
+        }
+        
+        Task newEvent = new Event(eventParts[0].trim(), fromToParts[0].trim(), fromToParts[1].trim());
+        tasks.addTask(newEvent);
+        ui.showAddedTask(newEvent, tasks.getTaskCount());
+        try {
+            storage.save(tasks.getTasks());
+        } catch (IOException e) {
+            System.out.println("An error occurred while saving tasks to the file.");
+        }
+        ui.showLineDivider();
+    }
+
+    /*
+     * Handles the find command.
+     * checks if the keyword is empty.
+     * 
+     * @param part The part of the command after the find keyword.
+     * @throws DukeException If an error occurs while finding the tasks.
      */
+    private void handleFind(String part) {
+        String keyword = part.trim();
+        if (keyword.isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! The keyword for find cannot be empty.\n" + lineDivider);
+            return;
+        }
+
+        ArrayList<Task> foundTasks = tasks.findTasks(keyword);
+        if (foundTasks.isEmpty()) {
+            ui.showErrorMsg("☹ OOPS!!! No matching tasks found with the given keyword.\n" + lineDivider);
+            return;
+        }
+        ui.showFoundTasks(foundTasks);
+        ui.showLineDivider();
+    }
+
     public static void main(String[] args) {
         new Duke("data/tasks.txt").run();
     }
-}
\ No newline at end of file
+}