From ce6ed02c5583f92e1db9f5edea74a7bd218d732a Mon Sep 17 00:00:00 2001
From: Tomislav Kaljevic <tomislav.kaljevic@qposoft.com>
Date: Thu, 3 Nov 2022 15:40:40 +0100
Subject: [PATCH 1/2] Http error interceptor with non-implemented methods

---
 .../http-error.interceptor.spec.ts            |  16 +++
 .../interceptors/http-error.interceptor.ts    | 120 ++++++++++++++++++
 src/app/core/interceptors/index.ts            |   1 +
 3 files changed, 137 insertions(+)
 create mode 100644 src/app/core/interceptors/http-error.interceptor.spec.ts
 create mode 100644 src/app/core/interceptors/http-error.interceptor.ts
 create mode 100644 src/app/core/interceptors/index.ts

diff --git a/src/app/core/interceptors/http-error.interceptor.spec.ts b/src/app/core/interceptors/http-error.interceptor.spec.ts
new file mode 100644
index 0000000..ad9d42d
--- /dev/null
+++ b/src/app/core/interceptors/http-error.interceptor.spec.ts
@@ -0,0 +1,16 @@
+import { TestBed } from '@angular/core/testing';
+
+import { HttpErrorInterceptor } from './http-error.interceptor';
+
+describe('HttpErrorInterceptor', () => {
+  beforeEach(() => TestBed.configureTestingModule({
+    providers: [
+      HttpErrorInterceptor
+      ]
+  }));
+
+  it('should be created', () => {
+    const interceptor: HttpErrorInterceptor = TestBed.inject(HttpErrorInterceptor);
+    expect(interceptor).toBeTruthy();
+  });
+});
diff --git a/src/app/core/interceptors/http-error.interceptor.ts b/src/app/core/interceptors/http-error.interceptor.ts
new file mode 100644
index 0000000..4d82243
--- /dev/null
+++ b/src/app/core/interceptors/http-error.interceptor.ts
@@ -0,0 +1,120 @@
+import { Injectable } from '@angular/core';
+import {
+  HttpErrorResponse,
+  HttpEvent,
+  HttpHandler,
+  HttpInterceptor,
+  HttpRequest,
+} from '@angular/common/http';
+import { Observable, throwError } from 'rxjs';
+import { catchError } from 'rxjs/operators';
+
+//TODO: It's necessary to inject a service (or any other mechanism) that could display error messages on UI.
+
+//TODO: It's necessary to add a logic for all methods that are not completed, based on system requirements.
+
+@Injectable()
+export class HttpErrorInterceptor implements HttpInterceptor {
+  constructor() {}
+
+  /**
+   * The interceptor method.
+   *
+   * @param req - Current request.
+   * @param next - HttpHandler.
+   */
+  public intercept(
+    req: HttpRequest<any>,
+    next: HttpHandler
+  ): Observable<HttpEvent<any>> {
+    return next.handle(req).pipe(
+      catchError((error: HttpErrorResponse) => {
+        const errorStatus = error.status;
+        // classify by code
+        const isClientError = errorStatus % 400 <= 99;
+        const isServerError = errorStatus % 500 <= 99;
+
+        if (isClientError) {
+          this.handleClientError(error);
+        } else if (isServerError) {
+          this.handleServerError(error);
+        } else {
+          this.defaultErrorHandler(error);
+        }
+
+        return throwError(error.message);
+      })
+    );
+  }
+
+  /**
+   * Will simply load notify.
+   *
+   * @param error - Error ocurred.
+   */
+  private defaultErrorHandler(error: HttpErrorResponse) {
+    throw new Error('Method not implemented.');
+  }
+
+  /**
+   * Handle all server errors (5xx).
+   *
+   * @param error - Error ocurred.
+   */
+  private handleServerError(error: HttpErrorResponse) {
+    throw new Error('Method not implemented.');
+  }
+
+  /**
+   * Handle all client errors (4xx).
+   *
+   * @param error - Error ocurred.
+   */
+  private handleClientError(error: HttpErrorResponse) {
+    const errorStatus = error.status;
+    switch (errorStatus) {
+      case 400:
+        this.handleValidationError(error);
+        break;
+      case 401:
+        this.handleAuthError(error);
+        break;
+      case 403:
+        this.handleUnauthorizedError(error);
+        break;
+      case 422:
+        this.handleValidationError(error);
+        break;
+      default:
+        this.defaultErrorHandler(error);
+        break;
+    }
+  }
+
+  /**
+   * Authorization error.
+   *
+   * @param error - Error ocurred.
+   */
+  private handleAuthError(error: HttpErrorResponse) {
+    throw new Error('Method not implemented.');
+  }
+
+  /**
+   * Not authorized.
+   *
+   * @param error Error that ocurred.
+   */
+  private handleUnauthorizedError(error: HttpErrorResponse) {
+    throw new Error('Method not implemented.');
+  }
+
+  /**
+   * Form Validation error method, here we'll iterate through each validation message in response
+   *
+   * @param error - Error ocurred.
+   */
+  private handleValidationError(error: HttpErrorResponse) {
+    throw new Error('Method not implemented.');
+  }
+}
diff --git a/src/app/core/interceptors/index.ts b/src/app/core/interceptors/index.ts
new file mode 100644
index 0000000..8fb032a
--- /dev/null
+++ b/src/app/core/interceptors/index.ts
@@ -0,0 +1 @@
+export * from './http-error.interceptor';

From 11622f3cd2ce83b37daf945a6a891c512073f3f4 Mon Sep 17 00:00:00 2001
From: Boris Jotic <boris.jotic@qposoft.com>
Date: Fri, 4 Nov 2022 12:28:36 +0100
Subject: [PATCH 2/2] removed sufficient 400 call

---
 src/app/core/interceptors/http-error.interceptor.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/app/core/interceptors/http-error.interceptor.ts b/src/app/core/interceptors/http-error.interceptor.ts
index 4d82243..941d561 100644
--- a/src/app/core/interceptors/http-error.interceptor.ts
+++ b/src/app/core/interceptors/http-error.interceptor.ts
@@ -73,9 +73,9 @@ export class HttpErrorInterceptor implements HttpInterceptor {
   private handleClientError(error: HttpErrorResponse) {
     const errorStatus = error.status;
     switch (errorStatus) {
-      case 400:
-        this.handleValidationError(error);
-        break;
+      // case 400:
+      //   this.handleValidationError(error);
+      //   break;
       case 401:
         this.handleAuthError(error);
         break;