google sign in implemented

.gitignore

@@ -0,0 +1,7 @@
+node_modules/
+.vscode/
+
+.env
+.env.local
+
+*.log

backend/db.js

@@ -1,7 +1,7 @@
 // Connecting to moongose
 const mongoose=require("mongoose");
 
-const mongoURL="mongodb://localhost:27017/task-manager";
+const mongoURL=process.env.MONGODB_URI
 
 const connecttoMongo=()=>{
     mongoose.connect(mongoURL,()=>{

backend/index.js

@@ -1,15 +1,28 @@
+require('dotenv').config()
 const express=require("express");
 const connecttoMongo=require("./db");
 const cors = require('cors');
-connecttoMongo();  //Connecting to mongo
+const passport = require('passport');
+const cookieSession = require('cookie-session');
+require('./passport.setup')
 
+connecttoMongo();  //Connecting to mongo
 
 const app=express();
-const port=80;
+const port= process.env.PORT || 3000;
+
 app.use(cors())
 
 app.use(express.json());
 
+app.use(cookieSession({
+    maxAge : 24 * 60 * 60 * 1000,
+    keys : ['sandip@low']
+}))
+
+app.use(passport.initialize())
+app.use(passport.session())
+
 app.get('/',(req,res)=>{
     res.send("Hello,Welcome to task manager");
 })

backend/models/User.js

@@ -3,6 +3,14 @@
 const mongoose = require('mongoose');
 
 const UserSchema = new mongoose.Schema({
+    provider: {
+        type: String,
+        default: "native",
+    },
+    providerId: {
+        type: String,
+        default: null
+    },
     name: String,
     email: {
         type: String,

backend/package.json

@@ -4,16 +4,21 @@
   "description": "backend of task manager app",
   "main": "index.js",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "start": "node index.js",
+    "dev": "nodemon index.js"
   },
   "author": "sujal",
   "license": "ISC",
   "dependencies": {
     "bcrypt": "^5.0.1",
+    "cookie-session": "^2.0.0",
     "cors": "^2.8.5",
+    "dotenv": "^16.0.3",
     "express": "^4.18.1",
     "express-validator": "^6.14.2",
     "jsonwebtoken": "^8.5.1",
-    "mongoose": "^6.5.1"
+    "mongoose": "^6.5.1",
+    "passport": "0.5.0",
+    "passport-google-oauth20": "^2.0.0"
   }
 }

backend/passport.setup.js

@@ -0,0 +1,51 @@
+const passport = require('passport')
+const GoogleStrategy = require('passport-google-oauth20').Strategy
+const User = require('./models/User')
+
+// serialize user through out the routes 
+passport.serializeUser((user, cb)=> {
+    cb(null, user)
+})
+
+passport.deserializeUser( async (id, cb)=> {
+    const user = await User.findById(id)
+    cb(null, user)
+})
+
+// use google strategy for google oauth login
+passport.use( 
+    new GoogleStrategy( {
+            clientID : process.env.GOOGLE_CLIENTID,
+            clientSecret : process.env.GOOGLE_CLIENTSECRET,
+            callbackURL : "/auth/google/redirect"
+        },
+        async (accessToken, refreshToken, profile, cb) => {
+            // Checking if the user already in database 🧐
+            const dbUser = await User.findOne({ email : profile._json.email })
+
+            if (dbUser) {
+                // Checking whether the user used to sign in using password, if so then we set the provider to be google from now...😘
+                if(dbUser.provider !== "google") {
+                    dbUser.update({
+                        provider : "google",
+                        providerId : profile._json.sub
+                    })
+                } 
+                // console.log("User already exists : "+dbUser)
+                cb(null, dbUser)
+            } 
+
+            else {
+                // There is no user with that email in database so we have to create that...🤜🏽🤛🏽
+                let user = await User.create({
+                    provider : "google",
+                    providerId : profile.id,
+                    name : profile.displayName,
+                    email : profile.emails[0].value
+                })
+                // console.log("New User Created : "+user)
+                cb(null, user)
+            }
+        }
+    )
+)

backend/routes/auth.js

@@ -5,6 +5,7 @@ const { body, validationResult } = require('express-validator');
 const bcrypt = require('bcrypt');
 const fetchUser=require('../middleware/fetchUser');
 const jwt = require('jsonwebtoken');   //using jwt(JSON web token for authorization)
+const passport = require('passport');
 
 const secret_key="Mynameissujal"  //secret key 
 
@@ -116,4 +117,21 @@ router.post('/getUser',fetchUser,async (req,res)=>{
     res.status(500).send("Internal server error")
   }
 })
+
+// ROUTE-4-----> Google OAuth SignIn (no login required)
+router.get('/google', passport.authenticate('google', {
+  scope : ['profile', 'email']
+}))
+
+// ROUTE-5-----> Google OAuth Redirect URI (no need to visit...🙂)
+router.get('/google/redirect', passport.authenticate('google'), (req, res)=> {
+  // res.json(req.user)
+  const data={
+    user:{
+      id:req.user.id
+    }
+  }
+  const token = jwt.sign(data, secret_key)
+  res.redirect(process.env.CLIENT_URI+"/redirect?token="+token)
+})
 module.exports = router