import express, { Application, Request, Response, NextFunction } from 'express';
import cors from 'cors';
import helmet from 'helmet';
import rateLimit from 'express-rate-limit';
import dotenv from 'dotenv';
import path from 'path';
import fs from 'fs';

import mongoose from 'mongoose';
import { connectDB } from './config/database';
import { errorHandler } from './middleware/errorHandler';
import { setupSwagger } from './config/swagger';

// Read version from package.json
const getAppVersion = (): string => {
  try {
    const pkgPath = path.join(__dirname, '..', 'package.json');
    const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
    return pkg.version || '0.0.0';
  } catch {
    return '0.0.0';
  }
};

// Import routes
import indexRoutes from './routes/index';
import authRoutes from './routes/auth';

dotenv.config();

const app: Application = express();
const PORT: number = parseInt(process.env.PORT || '8000');

// Connect to MongoDB
connectDB();

// Security middleware
app.use(helmet());
app.use(cors({
  origin: process.env.FRONTEND_URL || 'http://localhost:5000',
  credentials: true
}));

// Rate limiting
const limiter = rateLimit({
  windowMs: 15 * 60 * 1000, // 15 minutes
  max: 100, // limit each IP to 100 requests per windowMs
  message: 'Too many requests from this IP, please try again later.'
});
app.use('/api/', limiter);

// Body parsing middleware
app.use(express.json({ limit: '10mb' }));
app.use(express.urlencoded({ extended: true }));

// Setup Swagger documentation
setupSwagger(app);

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

// Health check endpoint
app.get('/health', (req: Request, res: Response) => {
  res.status(200).json({ 
    status: 'OK', 
    timestamp: new Date().toISOString(),
    uptime: process.uptime(),
    environment: process.env.NODE_ENV || 'development',
    version: getAppVersion()
  });
});

// Error handling middleware (should be last)
app.use(errorHandler);

// 404 handler
app.use('*', (req: Request, res: Response) => {
  res.status(404).json({ 
    success: false, 
    message: 'Route not found',
    path: req.originalUrl
  });
});

// Graceful shutdown
const gracefulShutdown = async (signal: string) => {
  console.log(`\n${signal} received. Shutting down gracefully...`);
  try {
    await mongoose.connection.close();
    console.log('MongoDB connection closed.');
  } catch (err) {
    console.error('Error closing MongoDB connection:', err);
  }
  process.exit(0);
};

process.on('SIGTERM', () => gracefulShutdown('SIGTERM'));
process.on('SIGINT', () => gracefulShutdown('SIGINT'));

app.listen(PORT, '0.0.0.0', () => {
  console.log(`🚀 Server running on port ${PORT}`);
  console.log(`📱 Environment: ${process.env.NODE_ENV || 'development'}`);
  console.log(`📚 API Documentation: http://localhost:${PORT}/api-docs`);
});

export default app;