server.js

// server.js
const express = require('express');
const mongoose = require('mongoose');
const cors = require('cors');
const helmet = require('helmet');
const rateLimit = require('express-rate-limit');
require('dotenv').config();

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

const app = express();
const PORT = process.env.PORT || 3001;

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

// 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);

// CORS configuration
const corsOptions = {
  origin: [
    'http://localhost:9002',
    'https://enb-onchain-summer.vercel.app',
    'https://enb-onchain-summer.vercel.app/',
    // Add any other domains you might use
  ],
  credentials: true,
  optionsSuccessStatus: 200
};
app.use(cors(corsOptions));

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

// MongoDB connection
mongoose.connect(process.env.MONGODB_URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
})
.then(() => {
  console.log('✅ Connected to MongoDB');
})
.catch((error) => {
  console.error('❌ MongoDB connection error:', error);
  process.exit(1);
});

// Health check endpoint
app.get('/', (req, res) => {
  res.json({
    message: 'Onchain Summer Lagos Backend API',
    status: 'running',
    timestamp: new Date().toISOString(),
    endpoints: {
      'POST /api/nfts': 'Save minted NFT data',
      'GET /api/nfts/:walletAddress': 'Get user NFTs',
      'GET /api/health': 'Health check'
    }
  });
});

app.get('/api/health', (req, res) => {
  res.json({
    status: 'healthy',
    database: mongoose.connection.readyState === 1 ? 'connected' : 'disconnected',
    timestamp: new Date().toISOString(),
    uptime: process.uptime()
  });
});

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

// Error handling middleware
app.use((err, req, res, next) => {
  console.error('❌ Error:', err.stack);
  
  // Mongoose validation error
  if (err.name === 'ValidationError') {
    const errors = Object.values(err.errors).map(e => e.message);
    return res.status(400).json({
      success: false,
      message: 'Validation Error',
      errors
    });
  }
  
  // Mongoose duplicate key error
  if (err.code === 11000) {
    return res.status(400).json({
      success: false,
      message: 'Duplicate entry',
      error: 'This NFT has already been recorded'
    });
  }
  
  // Default error
  res.status(500).json({
    success: false,
    message: 'Internal server error',
    error: process.env.NODE_ENV === 'development' ? err.message : 'Something went wrong'
  });
});

// 404 handler
app.use('*', (req, res) => {
  res.status(404).json({
    success: false,
    message: 'Route not found',
    availableRoutes: [
      'GET /',
      'GET /api/health',
      'POST /api/nfts',
      'GET /api/nfts/:walletAddress'
    ]
  });
});

// Graceful shutdown
process.on('SIGTERM', () => {
  console.log('🔄 SIGTERM received, shutting down gracefully');
  mongoose.connection.close();
  process.exit(0);
});

process.on('SIGINT', () => {
  console.log('🔄 SIGINT received, shutting down gracefully');
  mongoose.connection.close();
  process.exit(0);
});

app.listen(PORT, () => {
  console.log(`🚀 Server running on port ${PORT}`);
  console.log(`📍 Environment: ${process.env.NODE_ENV || 'development'}`);
  console.log(`🌐 Frontend URL: https://enb-onchain-summer.vercel.app`);
});