server.js

const path = require('path');
const express = require('express');
const dotenv = require('dotenv');
const colors = require('colors');
const fileupload = require('express-fileupload');
const cookieParser = require('cookie-parser');
const mongoSanitize = require('express-mongo-sanitize');
const helmet = require('helmet');
const xss = require('xss-clean');
const hpp = require('hpp');
const rateLimit = require('express-rate-limit');
const errorHandler = require('./middleware/error');
const connectDB = require('./config/db');
const cors = require('cors');

// Load Environment
dotenv.config();

// Connect to MongoDB
connectDB();

const app = express();

// Middleware
app.use(cors());
app.use(express.static(path.join(__dirname, 'public')));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(fileupload());
app.use(cookieParser());

// Sanitize data - prevent NoSQL ijections
app.use(mongoSanitize());

// Headers for security
app.use(helmet());

// Prevent XSS
app.use(xss());

// Rate limiting
const limiter = rateLimit({
  windowMs: 10 * 60 * 1000, // 10 mins
  max: 100,
});
app.use(limiter);

// Prevent HTTP Parameter Pollution
app.use(hpp());

// Mounting Routers
app.use('/api/v1/bootcamps', require('./routes/bootcamps'));
app.use('/api/v1/courses', require('./routes/courses'));
app.use('/api/v1/auth', require('./routes/auth'));
app.use('/api/v1/reviews', require('./routes/reviews'));

// Error handling middleware
app.use(errorHandler);

const PORT = process.env.PORT || 3000;
const server = app.listen(PORT, console.log(`Listening on PORT: ${PORT}`.blue));

// Handle unhandled promise rejections
process.on('unhandledRejection', (err, promise) => {
  console.log(`Error: ${err.message}`.red);

  // Close server and exit process
  server.close(() => process.exit(1));
});