#153 build an example for firebase-auth

.vscode/settings.json

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+{
+    "githubPullRequests.ignoredPullRequestBranches": [
+        "master"
+    ]
+}

firebase-auth/config/cred.json

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+{
+  "type": "service_account",
+  "project_id": "xxxxxxxxx",
+  "private_key_id": "xxxxxxxxxxxxxxxxxxx",
+  "private_key": "-----BEGIN PRIVATE KEY-----\xxxxxxxxxxxxxxxxxxxxxxx+\nx/xxxxxxxxxxxxxxxxxxxx/xxxxxxxxxxxxxxxxxxxxxxx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\nOMaetbDeKjp3aTdVeVotLEc=\n-----END PRIVATE KEY-----\n",
+  "client_email": "firebase-adminsdk-xxxxx@xxxxxxxxx.iam.gserviceaccount.com",
+  "client_id": "xxxxxxxxx",
+  "auth_uri": "https://accounts.google.com/o/oauth2/auth",
+  "token_uri": "https://oauth2.googleapis.com/token",
+  "auth_provider_x509_cert_url": "https://www.googleapis.com/oauth2/v1/certs",
+  "client_x509_cert_url": "https://www.googleapis.com/robot/v1/metadata/x509/firebase-adminsdk-5xxxxxxxx%40xxxxxxxxx.iam.gserviceaccount.com",
+  "universe_domain": "googleapis.com"
+}

firebase-auth/config/firebase.go

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+package config
+
+import (
+	"context"
+	"fmt"
+	"log"
+
+	"firebase.google.com/go"
+	"firebase.google.com/go/auth"
+	"google.golang.org/api/option"
+)
+
+const (
+	ErrorFirebaseInit = "error initializing Firebase app"
+	ErrorAuthClient = "error getting Auth client"
+)
+func InitializeFirebase() (*auth.Client, error){
+	//add cred file downloaded from project settings -> service accounts
+	opt := option.WithCredentialsFile("/Users/vinayak/Documents/oss/examples/firebase-auth/config/cred.json")
+
+	//init new app on firebasea
+	app, err := firebase.NewApp(context.Background(), nil , opt)
+	if err != nil {
+		log.Fatalf(ErrorFirebaseInit+": %v\n",err)
+		return nil, fmt.Errorf(ErrorFirebaseInit)
+	}
+
+	//init new auth app client
+	authClient, err := app.Auth(context.Background())
+	if err != nil {
+		log.Fatalf(ErrorAuthClient+": %v\n", err)
+		return nil, err
+	}
+
+	return authClient, nil
+
+}

firebase-auth/handlers/auth.go

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+package handlers
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/gin-gonic/examples/firebase-auth/utils"
+
+	"firebase.google.com/go/auth"
+	"github.com/gin-gonic/gin"
+)
+
+//turn on auth type on firebase console what ever type you wanna use for auth
+
+type LoginRequest struct {
+	Token string `json:"token" binding:"required"`
+}
+
+type SignupRequest struct {
+	Email string `json:"email" binding:"required"`
+	Username string `json:"username" binding:"required"`
+	Password string `json:"password" binding:"required"`
+}
+
+
+type GoogleSignupRequest struct {
+	IDToken string `json:"id_token" binding:"required"`
+}
+
+//Signup handler
+func SignupHandler(firebaseAuth *auth.Client) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		var req SignupRequest
+		if err := c.ShouldBindJSON(&req); err != nil {
+			utils.RespondWithError(c, http.StatusBadRequest, "Invalid request" )
+			return 
+		}
+
+		existing, _ := firebaseAuth.GetUserByEmail(context.Background(), req.Email)
+		if existing != nil {
+			utils.RespondWithError(c, http.StatusNotAcceptable, "User already exisit with this email")
+			return
+		}
+
+		params := (&auth.UserToCreate{}).
+				Email(req.Email).
+				Password(req.Password).
+				DisplayName(req.Username)
+
+
+		newUser, err := firebaseAuth.CreateUser(context.Background(), params)
+		if err != nil {
+			utils.RespondWithError(c, http.StatusInternalServerError, "Failed to create user")
+			return
+		}		
+
+		c.JSON(http.StatusCreated, gin.H{
+			"message":"User Created",
+			"uid":newUser.UID,
+		})
+	}
+}
+
+func SigninWithGoogleHandler(firebaseAuth *auth.Client)gin.HandlerFunc {
+	return func(c *gin.Context) {
+		var req GoogleSignupRequest
+		if err := c.ShouldBindJSON(&req); err != nil {
+			utils.RespondWithError(c, http.StatusBadRequest, "Invalid Request")
+			return
+		}
+
+		//verify google 
+		gUser, err := firebaseAuth.VerifyIDToken(context.Background(), req.IDToken)
+		if err!= nil {
+			utils.RespondWithError(c, http.StatusBadRequest,"Failed to verify google id token")
+			return
+		}
+
+		c.Set("user", gUser.UID)
+		c.JSON(http.StatusAccepted, gin.H{
+			"message":"Login successful via google",
+			"uid": gUser.UID,
+		})		
+
+	}
+
+}
+
+type EmailLoginRequest struct {
+    Email    string `json:"email" binding:"required"`
+    Password string `json:"password" binding:"required"`
+}
+
+type FirebaseAuthResponse struct {
+    IdToken string `json:"idToken"`
+    Error   struct {
+        Message string `json:"message"`
+    } `json:"error"`
+}
+
+// Firebase project-specific endpoint for REST API
+const firebaseAuthURL = "https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?key=YOUR_FIREBASE_WEB_API_KEY"
+
+// EmailLoginHandler handles user login with email and password
+func EmailLoginHandler(firebaseAuth *auth.Client) gin.HandlerFunc {
+    return func(c *gin.Context) {
+		fmt.Println("step 0")
+
+		var req EmailLoginRequest
+		if err := c.ShouldBindJSON(&req); err != nil {
+			utils.RespondWithError(c, http.StatusBadRequest, "Invalid request" )
+			return 
+		}
+
+		fmt.Println("step 1")
+
+		_,err := firebaseAuth.GetUserByEmail(c, req.Email)
+		if err != nil {
+			utils.RespondWithError(c, http.StatusBadRequest, "Invalid Email" )
+			return 
+		}
+
+        // Create the payload for Firebase REST API
+        payload := map[string]string{
+            "email":             req.Email,
+            "password":          req.Password,
+            "returnSecureToken": "true",
+        }
+        payloadBytes, _ := json.Marshal(payload)
+
+		fmt.Println("step 2")
+
+        // Make the request to Firebase REST API
+        resp, err := http.Post(firebaseAuthURL, "application/json", bytes.NewBuffer(payloadBytes))
+        if err != nil || resp.StatusCode != http.StatusOK {
+            utils.RespondWithError(c, http.StatusUnauthorized, "Invalid email or password")
+            return
+        }
+        defer resp.Body.Close()
+
+		fmt.Println("step 3")
+
+        // Parse the response
+        body, _ := ioutil.ReadAll(resp.Body)
+        var authResp FirebaseAuthResponse
+        if err := json.Unmarshal(body, &authResp); err != nil {
+            utils.RespondWithError(c, http.StatusInternalServerError, "Failed to parse response from Firebase")
+            return
+        }
+		fmt.Println("step 4")
+
+        if authResp.IdToken == "" {
+            utils.RespondWithError(c, http.StatusUnauthorized, authResp.Error.Message)
+            return
+        }
+		fmt.Println("step 5")
+
+        c.JSON(http.StatusOK, gin.H{
+            "message": "Login successful",
+            "token":   authResp.IdToken,
+        })
+    }
+}
+
+func LoginHandler(firebaseAuth *auth.Client) gin.HandlerFunc {
+	return func(ctx *gin.Context) {
+		var req LoginRequest
+		if err := ctx.ShouldBindJSON(&req); err != nil {
+			utils.RespondWithError(ctx, http.StatusBadRequest, "Invalid Request")
+			return
+		}
+
+		token, err := firebaseAuth.VerifyIDToken(context.Background(), req.Token)
+		if err != nil {
+			utils.RespondWithError(ctx, http.StatusUnauthorized, "Invalid Token")
+			return
+		}
+
+
+		ctx.JSON(http.StatusAccepted, gin.H{
+			"message":"Login successfull",
+			"uid": token.UID,
+		})
+
+	}
+}
+
+func ProfileHandler(c *gin.Context){
+	user, ok := c.Get("user")
+	if !ok {
+		c.JSON(http.StatusNotFound, gin.H{
+			"message":"profile not found",
+		})
+	}
+	c.JSON(http.StatusFound, gin.H{
+		"message":"profile found",
+		"user":user,
+	})
+}

firebase-auth/main.go

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+package main
+
+import (
+	"log"
+
+	"github.com/gin-gonic/examples/firebase-auth/config"
+	"github.com/gin-gonic/examples/firebase-auth/routes"
+	"github.com/gin-gonic/gin"
+)
+
+const (
+	ErrStartServer = "error starting server"
+	PORT = "8080"
+)
+func main(){
+
+	//init firebase
+	firebaseAuth, err := config.InitializeFirebase()
+	if err != nil {
+		log.Fatalf(config.ErrorFirebaseInit+": %v",err)
+	}
+
+	//set up router
+	router := gin.Default()
+
+	//register routes
+	routes.RegisterRoutes(router, firebaseAuth)
+
+	//start server
+	if err := router.Run(":"+PORT); err != nil {
+		log.Fatalf("err starting server ")
+	}
+
+}

firebase-auth/middlewares/auth.go

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+package middlewares
+
+import (
+	"context"
+	"net/http"
+
+	"firebase.google.com/go/auth"
+	"github.com/gin-gonic/examples/firebase-auth/utils"
+	"github.com/gin-gonic/gin"
+)
+
+
+func AuthMiddleware(firebaseAuth *auth.Client) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		token := c.GetHeader("Authorization")
+		if token == "" {
+			utils.RespondWithError(c, http.StatusUnauthorized, "Authorization header required")
+			c.Abort()
+			return 
+		}
+
+		decodeToken, err := firebaseAuth.VerifyIDToken(context.Background(), token)
+		if err != nil {
+			utils.RespondWithError(c, http.StatusUnauthorized, "Invalid token")
+			c.Abort()
+			return
+		}
+
+		c.Set("user", decodeToken.UID)
+		c.Next()
+
+	}
+}

firebase-auth/routes/routes.go

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+package routes
+
+import (
+	"firebase.google.com/go/auth"
+	"github.com/gin-gonic/examples/firebase-auth/handlers"
+	"github.com/gin-gonic/examples/firebase-auth/middlewares"
+	"github.com/gin-gonic/gin"
+)
+
+//register
+
+func RegisterRoutes(router *gin.Engine, firebaseAuth *auth.Client){
+
+	//unprotected
+	router.POST("/signup", handlers.SignupHandler(firebaseAuth))
+	router.POST("/login", handlers.LoginHandler(firebaseAuth))
+	router.POST("/email", handlers.EmailLoginHandler(firebaseAuth))
+
+	//using google token(third party)
+	router.POST("/google", handlers.SigninWithGoogleHandler(firebaseAuth))
+
+	//protected routes
+	protected := router.Group("/protected")
+	protected.Use(middlewares.AuthMiddleware(firebaseAuth))
+	{
+		protected.GET("/profile", handlers.ProfileHandler)
+	}
+
+}

firebase-auth/utils/response.go

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+package utils
+
+import "github.com/gin-gonic/gin"
+
+
+func RespondWithError(c *gin.Context, code int, message string){
+	c.JSON(code, gin.H{"error":message})
+	c.Abort()
+}