1. Create express server that has authorized endpoint using JWT (JSON Web Token) library. 
2. Create express server that connects to Mongo DB database to authenticate the user and generate 
the authorized token to access the protected endpoints. 


const mongoose = require("mongoose");

//models/User.js

const userSchema = new mongoose.Schema({
  name: { type: String, required: true },
  email: { type: String, required: true, unique: true },
  password: { type: String, required: true },
  createdAt: { type: Date, default: Date.now }
});

module.exports = mongoose.model("User", userSchema);




//middleware/auth.js)

const jwt = require('jsonwebtoken');
const dotenv = require('dotenv');
dotenv.config();

module.exports = function (req, res, next) {
  const token = req.header('Authorization')?.split(' ')[1];
  if (!token) return res.status(401).json({ message: 'Access Denied: No Token Provided' });

  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    req.user = decoded;
    next();
  } catch (err) {
    res.status(400).json({ message: 'Invalid Token' });
  }
};





//routes/auth.js

const express = require('express');
const jwt = require('jsonwebtoken');
const User = require('../models/User');
const auth = require('../middleware/auth');
const dotenv = require('dotenv');

dotenv.config();
const router = express.Router();

// Register
router.post('/register', async (req, res) => {
  const { username, password } = req.body;
  try {
    const user = new User({ username, password });
    await user.save();
    res.status(201).json({ message: 'User registered' });
  } catch (err) {
    res.status(400).json({ message: 'User already exists' });
  }
});

// Login
router.post('/login', async (req, res) => {
  const { username, password } = req.body;
  const user = await User.findOne({ username });

  if (!user || !(await user.comparePassword(password)))
    return res.status(401).json({ message: 'Invalid credentials' });

  const token = jwt.sign({ id: user._id, username: user.username }, process.env.JWT_SECRET, {
    expiresIn: '1h',
  });

  res.json({ token });
});

// Protected route
router.get('/protected', auth, (req, res) => {
  res.json({ message: Hello ${req.user.username}, you accessed a protected route! });
});

module.exports = router;






//server.js
const express = require('express');
const mongoose = require('mongoose');
const dotenv = require('dotenv');
const authRoutes = require('./routes/auth');

dotenv.config();
const app = express();
app.use(express.json());

// Connect to MongoDB
mongoose.connect(process.env.MONGO_URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
}).then(() => console.log('MongoDB Connected'))
  .catch(err => console.error('MongoDB Connection Error:', err));

// Routes
app.use('/api', authRoutes);

// Start server
const PORT = process.env.PORT || 5000;
app.listen(PORT, () => console.log(Server running on port ${PORT}));