require('dotenv').config();
const express = require('express');
const cors = require('cors');
const helmet = require('helmet');
const compression = require('compression');
const rateLimit = require('express-rate-limit');
const path = require('path');

// Import database
const db = require('./src/database/models');

// Import routes (Modular Monolith Structure)
const authRoutes = require('./src/modules/auth/auth.routes');
const onboardingRoutes = require('./src/modules/onboarding/onboarding.routes');
const selfServiceRoutes = require('./src/modules/self-service/self-service.routes');
const masterRoutes = require('./src/modules/master/master.routes');
const settlementRoutes = require('./src/modules/settlement/settlement.routes');
const collaborationRoutes = require('./src/modules/collaboration/collaboration.routes');

// Import common middleware & utils
const errorHandler = require('./src/common/middleware/errorHandler');
const logger = require('./src/common/utils/logger');

// Initialize Express app
const app = express();

// Security middleware
app.use(helmet());
app.use(cors({
  origin: process.env.FRONTEND_URL || 'http://localhost:5173',
  credentials: true
}));

// Rate limiting
const limiter = rateLimit({
  windowMs: parseInt(process.env.RATE_LIMIT_WINDOW_MS) || 15 * 60 * 1000, // 15 minutes
  max: parseInt(process.env.RATE_LIMIT_MAX_REQUESTS) || 100,
  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, limit: '10mb' }));

// Compression
app.use(compression());

// Static files (uploaded documents)
app.use('/uploads', express.static(path.join(__dirname, 'uploads')));

// Request logging
app.use((req, res, next) => {
  logger.info(`${req.method} ${req.path}`, {
    ip: req.ip,
    userAgent: req.get('user-agent')
  });
  next();
});

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

// API Routes (Modular)
app.use('/api/auth', authRoutes);
app.use('/api/onboarding', onboardingRoutes);
app.use('/api/self-service', selfServiceRoutes);
app.use('/api/master', masterRoutes);
app.use('/api/settlement', settlementRoutes);
app.use('/api/collaboration', collaborationRoutes);

// Backward Compatibility Aliases
app.use('/api/applications', onboardingRoutes);
app.use('/api/resignations', require('./src/modules/self-service/resignation.routes'));
app.use('/api/constitutional', (req, res, next) => {
  // Map /api/constitutional to /api/self-service/constitutional
  req.url = '/constitutional' + req.url;
  next();
}, selfServiceRoutes);
app.use('/api/relocations', (req, res, next) => {
  // Map /api/relocations to /api/self-service/relocation
  req.url = '/relocation' + req.url;
  next();
}, selfServiceRoutes);
app.use('/api/outlets', require('./src/modules/master/outlet.routes'));
app.use('/api/finance', settlementRoutes);
app.use('/api/worknotes', collaborationRoutes);

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

// Global error handler
app.use(errorHandler);

// Database connection and server start
const PORT = process.env.PORT || 5000;

const startServer = async () => {
  try {
    // Test database connection
    await db.sequelize.authenticate();
    logger.info('Database connection established successfully');

    // Sync database (in development only)
    if (process.env.NODE_ENV === 'development') {
      await db.sequelize.sync({ alter: false });
      logger.info('Database models synchronized');
    }

    // Start server
    app.listen(PORT, () => {
      logger.info(`🚀 Server running on port ${PORT}`);
      logger.info(`📍 Environment: ${process.env.NODE_ENV}`);
      logger.info(`🔗 API Base URL: http://localhost:${PORT}/api`);
    });
  } catch (error) {
    logger.error('Unable to start server:', error);
    process.exit(1);
  }
};

// Handle unhandled promise rejections
process.on('unhandledRejection', (err) => {
  logger.error('Unhandled Promise Rejection:', err);
  process.exit(1);
});

// Handle uncaught exceptions
process.on('uncaughtException', (err) => {
  logger.error('Uncaught Exception:', err);
  process.exit(1);
});

// Graceful shutdown
process.on('SIGTERM', async () => {
  logger.info('SIGTERM signal received: closing HTTP server');
  await db.sequelize.close();
  process.exit(0);
});

startServer();

module.exports = app;