telegram-management-system/marketing-agent/services/billing-service/src/app.js

import express from 'express';
import cors from 'cors';
import helmet from 'helmet';
import rateLimit from 'express-rate-limit';
import mongoose from 'mongoose';
import { config } from './config/index.js';
import { logger, requestLogger, errorLogger } from './utils/logger.js';

// Import routes
import subscriptionRoutes from './routes/subscriptions.js';
import invoiceRoutes from './routes/invoices.js';
import paymentMethodRoutes from './routes/payment-methods.js';
import transactionRoutes from './routes/transactions.js';
import webhookRoutes from './routes/webhooks.js';

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

// Security middleware
app.use(helmet());
app.use(cors(config.cors));

// Rate limiting
const limiter = rateLimit(config.rateLimit);
app.use('/api/', limiter);

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

// Webhook routes (before body parsing for raw body)
app.use('/webhooks', webhookRoutes);

// Request logging
app.use(requestLogger);

// API routes
app.use('/api/subscriptions', subscriptionRoutes);
app.use('/api/invoices', invoiceRoutes);
app.use('/api/payment-methods', paymentMethodRoutes);
app.use('/api/transactions', transactionRoutes);

// Health check
app.get('/health', (req, res) => {
  res.json({
    status: 'healthy',
    service: 'billing-service',
    timestamp: new Date().toISOString(),
    uptime: process.uptime(),
    environment: config.env
  });
});

// Error handling
app.use(errorLogger);

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

// Global error handler
app.use((err, req, res, next) => {
  const status = err.status || 500;
  const message = err.message || 'Internal server error';
  
  res.status(status).json({
    success: false,
    error: message,
    ...(config.env === 'development' && { stack: err.stack })
  });
});

// Database connection
export async function connectDB() {
  try {
    await mongoose.connect(config.mongodb.uri, {
      useNewUrlParser: true,
      useUnifiedTopology: true
    });
    logger.info('MongoDB connected successfully');
  } catch (error) {
    logger.error('MongoDB connection error:', error);
    process.exit(1);
  }
}

// Graceful shutdown
export function setupGracefulShutdown(server) {
  const shutdown = async (signal) => {
    logger.info(`${signal} received, starting graceful shutdown`);
    
    server.close(() => {
      logger.info('HTTP server closed');
    });
    
    try {
      await mongoose.connection.close();
      logger.info('MongoDB connection closed');
      process.exit(0);
    } catch (error) {
      logger.error('Error during shutdown:', error);
      process.exit(1);
    }
  };
  
  process.on('SIGTERM', () => shutdown('SIGTERM'));
  process.on('SIGINT', () => shutdown('SIGINT'));
}

export default app;