server.js

/**
 * Local Storage API - Main Server
 * 
 * A sophisticated Node.js web API for file storage with S3-like functionality.
 * Features:
 * - File upload, download, and deletion
 * - Chunked uploads for large files
 * - MySQL database for metadata storage
 * - JWT-based authentication
 * - Rate limiting and security headers
 * - CORS support
 * 
 * @author Local Storage API
 * @version 1.0.0
 */

const express = require('express');
const path = require('path');
require('dotenv').config();

// Import configuration
const config = require('./config/app');
const { testConnection, syncDatabase } = require('./config/database');

// Import middleware
const {
  corsMiddleware,
  helmetMiddleware,
  apiLimiter,
  sanitizeRequest,
  notFoundHandler,
  errorHandler
} = require('./middleware');

// Import routes
const routes = require('./routes');

// Create Express application
const app = express();

// ===========================================
// MIDDLEWARE CONFIGURATION
// ===========================================

// Trust proxy (for rate limiting behind reverse proxy)
app.set('trust proxy', 1);

// Security headers with Helmet
app.use(helmetMiddleware);

// CORS configuration
app.use(corsMiddleware);

// Parse JSON bodies
app.use(express.json({ limit: '10mb' }));

// Parse URL-encoded bodies
app.use(express.urlencoded({ extended: true, limit: '10mb' }));

// Sanitize request data
app.use(sanitizeRequest);

// Apply rate limiting to all API routes
app.use('/api', apiLimiter);

// ===========================================
// ROUTES
// ===========================================

// Mount API routes
app.use('/api', routes);

// Serve static files from uploads directory (for public files)
// Note: This is optional and should be secured in production
if (config.server.env === 'development') {
  app.use('/uploads', express.static(path.resolve(config.upload.dir)));
}

// Root endpoint
app.get('/', (req, res) => {
  res.json({
    success: true,
    message: 'Welcome to Local Storage API',
    version: '1.0.0',
    documentation: '/api',
    health: '/api/health'
  });
});

// ===========================================
// ERROR HANDLING
// ===========================================

// Handle 404 - Route not found
app.use(notFoundHandler);

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

// ===========================================
// SERVER STARTUP
// ===========================================

/**
 * Initialize and start the server
 */
const startServer = async () => {
  try {
    console.log('🚀 Starting Local Storage API...');
    console.log(`📍 Environment: ${config.server.env}`);

    // Test database connection
    console.log('🔌 Connecting to database...');
    const dbConnected = await testConnection();
    
    if (!dbConnected) {
      console.error('❌ Failed to connect to database. Please check your configuration.');
      console.log('💡 Make sure MySQL is running and the database exists.');
      console.log('💡 You can create the database with: CREATE DATABASE local_storage_api;');
      process.exit(1);
    }

    // Sync database models
    console.log('📊 Synchronizing database models...');
    await syncDatabase({ alter: config.server.env === 'development' });

    // Ensure upload directories exist
    const { ensureUploadDirs } = require('./services/uploadService');
    await ensureUploadDirs();
    console.log('📁 Upload directories ready');

    // Start HTTP server
    const server = app.listen(config.server.port, config.server.host, () => {
      console.log('');
      console.log('='.repeat(50));
      console.log('✅ Local Storage API is running!');
      console.log('='.repeat(50));
      console.log(`🌐 URL: http://${config.server.host}:${config.server.port}`);
      console.log(`📚 API Docs: http://${config.server.host}:${config.server.port}/api`);
      console.log(`❤️  Health: http://${config.server.host}:${config.server.port}/api/health`);
      console.log('='.repeat(50));
      console.log('');
    });

    // Graceful shutdown handling
    const gracefulShutdown = async (signal) => {
      console.log(`\n📴 Received ${signal}. Shutting down gracefully...`);
      
      server.close(async () => {
        console.log('🔌 HTTP server closed');
        
        // Close database connection
        const { sequelize } = require('./config/database');
        await sequelize.close();
        console.log('🔌 Database connection closed');
        
        console.log('👋 Goodbye!');
        process.exit(0);
      });

      // Force close after 10 seconds
      setTimeout(() => {
        console.error('⚠️  Could not close connections in time, forcefully shutting down');
        process.exit(1);
      }, 10000);
    };

    // Listen for termination signals
    process.on('SIGTERM', () => gracefulShutdown('SIGTERM'));
    process.on('SIGINT', () => gracefulShutdown('SIGINT'));

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

    // Handle unhandled promise rejections
    process.on('unhandledRejection', (reason, promise) => {
      console.error('❌ Unhandled Rejection at:', promise, 'reason:', reason);
      process.exit(1);
    });

  } catch (error) {
    console.error('❌ Failed to start server:', error);
    process.exit(1);
  }
};

// Start the server
startServer();

// Export app for testing
module.exports = app;