require('dotenv').config();
const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const helmet = require('helmet');
const rateLimit = require('express-rate-limit');
const morgan = require('morgan');
const cookieParser = require('cookie-parser');

const app = express();

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

// Middleware
app.use(cors({
  origin: process.env.CLIENT_URL,
  credentials: true
}));
app.use(helmet());
app.use(express.json());
app.use(cookieParser());
app.use(morgan('dev'));

// Rate limiting
const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100 // limit each IP to 100 requests per windowMs
});
app.use(limiter);

// Routes
const authRoutes = require('./routes/auth');
const userRoutes = require('./routes/users');
const courseRoutes = require('./routes/courses');
const enrollmentRoutes = require('./routes/enrollments');
const certificateRoutes = require('./routes/certificates');
const paymentRoutes = require('./routes/payments');

app.use('/api/auth', authRoutes);
app.use('/api/users', userRoutes);
app.use('/api/courses', courseRoutes);
app.use('/api/enrollments', enrollmentRoutes);
app.use('/api/certificates', certificateRoutes);
app.use('/api/payments', paymentRoutes);

// Error handling
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).json({ message: 'Internal Server Error' });
});

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