Added sign out feature and actual balance feature

Dockerfile

@@ -0,0 +1,3 @@
+FROM mongo:4.4.7
+RUN echo "rs.initiate();" > /docker-entrypoint-initdb.d/replica-init.js
+CMD [ "--replSet", "rs" ]

backend/config.js

@@ -0,0 +1,3 @@
+const JWT_SECRET="mysecret";
+
+module.exports=JWT_SECRET;

backend/db.js

@@ -0,0 +1,28 @@
+const mongoose = require('mongoose');
+
+main().catch(err => console.log(err));
+
+async function main() {
+  await mongoose.connect('mongodb://localhost:27017/paytm');
+  console.log("connected to db");
+}
+
+const userSchema=mongoose.Schema({
+    firstName:String,
+    lastName:String,
+    password:String,
+    username:String
+});
+
+const accountSchema=mongoose.Schema({
+  userId:{
+    type:mongoose.Schema.Types.ObjectId,
+    ref:'User'
+  },
+  balance:Number
+});
+const User=mongoose.model('User',userSchema);
+const Account=mongoose.model('Account',accountSchema);
+module.exports={
+    User,Account
+}

backend/index.js

@@ -1,3 +1,12 @@
 const express = require("express");
+const mainRouter = require("./routes/index");
+const app=express();
+const cors=require("cors");
+app.use(cors());
+app.use(express.json());
 
+app.use('/api/v1',mainRouter);
 
+app.listen(3000,()=>{
+    console.log("listening to port 3000");
+})

backend/middleware.js

@@ -0,0 +1,23 @@
+const jwt=require("jsonwebtoken");
+const JWT_SECRET=require("./config");
+
+const authMiddleware=(req,res,next)=>{
+    const authHeader=req.headers.authorization;
+    if(!authHeader || !authHeader.startsWith("Bearer ")){
+        return res.json({msg:"invalid token"})
+    }
+
+    const token=authHeader.split(' ')[1];
+    try{
+        const decoded=jwt.verify(token,JWT_SECRET);
+        req.userId=decoded.userId;
+        next();
+    }
+    catch(err){
+        console.log(err);
+        return res.json({msg:"error in jwt verification"})
+    }
+}
+module.exports={
+    authMiddleware
+}

backend/package.json

@@ -10,8 +10,10 @@
   "author": "",
   "license": "ISC",
   "dependencies": {
+    "cors": "^2.8.5",
     "express": "^4.18.2",
-    "mongoose": "^8.1.0",
-    "zod": "^3.22.4"
+    "jsonwebtoken": "^9.0.2",
+    "mongoose": "^8.5.1",
+    "zod": "^3.23.8"
   }
 }