const { app, initializeApp } = require('./app');
const { closeConnection } = require('./config/database');
const { closeRedisConnection } = require('./config/redis');
const { closeQueues } = require('./config/bullmq');
const config = require('./config/config.json');

const PORT = config.server.port || 3000;
const HOST = '0.0.0.0';

let server;

/**
 * Start Server
 */
const startServer = async () => {
  try {
    // Initialize application (database, models, etc.)
    await initializeApp();
    
    // Start Express server
    server = app.listen(PORT, HOST, () => {
      console.log('');
      console.log('╔════════════════════════════════════════════════════════╗');
      console.log('║   🚀 Sena School Management API Server Started       ║');
      console.log('╠════════════════════════════════════════════════════════╣');
      console.log(`║   Environment: ${config.server.env.padEnd(38)} ║`);
      console.log(`║   Server URL:  http://${HOST}:${PORT}${' '.repeat(30 - HOST.length - PORT.toString().length)} ║`);
      console.log(`║   API Base:    http://${HOST}:${PORT}/api${' '.repeat(25 - HOST.length - PORT.toString().length)} ║`);
      console.log(`║   Health:      http://${HOST}:${PORT}/health${' '.repeat(22 - HOST.length - PORT.toString().length)} ║`);
      console.log('╠════════════════════════════════════════════════════════╣');
      console.log('║   📊 Services Status:                                 ║');
      console.log('║   ✅ MySQL Database Connected (senaai.tech:11001)     ║');
      console.log('║   ✅ Redis Sentinel Connected (senaai.tech)           ║');
      console.log('║   ✅ BullMQ Queues Initialized                        ║');
      console.log('╚════════════════════════════════════════════════════════╝');
      console.log('');
      console.log('📝 Available Endpoints:');
      console.log(`   GET  /health                - Health check`);
      console.log(`   GET  /api                   - API information`);
      console.log(`   GET  /api/schools           - List schools`);
      console.log(`   POST /api/schools           - Create school`);
      console.log(`   GET  /api/queues/status     - Queue metrics`);
      console.log(`   GET  /api/cache/stats       - Cache statistics`);
      console.log('');
      console.log('🔧 To start the BullMQ worker:');
      console.log('   node workers/databaseWriteWorker.js');
      console.log('');
    });
    
    // Handle server errors
    server.on('error', (error) => {
      console.error('❌ Server error:', error.message);
      process.exit(1);
    });
    
  } catch (error) {
    console.error('❌ Failed to start server:', error.message);
    process.exit(1);
  }
};

/**
 * Graceful Shutdown
 */
const gracefulShutdown = async (signal) => {
  console.log('');
  console.log(`⚠️  ${signal} received. Starting graceful shutdown...`);
  
  // Stop accepting new connections
  if (server) {
    server.close(async () => {
      console.log('✅ HTTP server closed');
      
      try {
        // Close database connections
        await closeConnection();
        
        // Close Redis connection
        await closeRedisConnection();
        
        // Close BullMQ queues
        await closeQueues();
        
        console.log('✅ All connections closed gracefully');
        process.exit(0);
      } catch (error) {
        console.error('❌ Error during shutdown:', error.message);
        process.exit(1);
      }
    });
    
    // Force close after 10 seconds
    setTimeout(() => {
      console.error('⚠️  Forcing shutdown after timeout');
      process.exit(1);
    }, 10000);
  } else {
    process.exit(0);
  }
};

/**
 * Handle Uncaught Exceptions
 */
process.on('uncaughtException', (error) => {
  console.error('💥 UNCAUGHT EXCEPTION! Shutting down...');
  console.error(error.name, error.message);
  console.error(error.stack);
  process.exit(1);
});

/**
 * Handle Unhandled Promise Rejections
 */
process.on('unhandledRejection', (error) => {
  console.error('💥 UNHANDLED REJECTION! Shutting down...');
  console.error(error.name, error.message);
  gracefulShutdown('UNHANDLED_REJECTION');
});

/**
 * Handle Termination Signals
 */
process.on('SIGTERM', () => gracefulShutdown('SIGTERM'));
process.on('SIGINT', () => gracefulShutdown('SIGINT'));

/**
 * Start the server
 */
startServer();

module.exports = { server };