/**
 * LandveX Simple Gateway
 *
 * Unifies all backend services without external dependencies.
 * Uses only Node.js built-in modules.
 */

const http = require('http');
const url = require('url');

const PORT = process.env.PORT || 3004;

// Service registry - only running services
const services = {
  intelligence: { host: 'localhost', port: 3002, path: '/api/v1', status: 'unknown' },
  // apollo: { host: 'localhost', port: 3001, path: '/api/apollo', status: 'unknown' },
  // ledger: { host: 'localhost', port: 3250, path: '', status: 'unknown' },
  // incidents: { host: 'localhost', port: 3303, path: '', status: 'unknown' },
};

// Simple proxy function
function proxyRequest(req, res, target) {
  const options = {
    hostname: target.host,
    port: target.port,
    path: req.url,
    method: req.method,
    headers: {
      ...req.headers,
      host: `${target.host}:${target.port}`,
    },
  };

  const proxyReq = http.request(options, (proxyRes) => {
    res.writeHead(proxyRes.statusCode, proxyRes.headers);
    proxyRes.pipe(res);
  });

  proxyReq.on('error', (err) => {
    console.error(`Proxy error: ${err.message}`);
    res.statusCode = 502;
    res.end(JSON.stringify({ error: 'Bad Gateway', message: err.message }));
  });

  req.pipe(proxyReq);
}

// Health check function
async function checkServiceHealth(name, service) {
  return new Promise((resolve) => {
    const req = http.request({
      hostname: service.host,
      port: service.port,
      path: '/health',
      method: 'GET',
      timeout: 5000,
    }, (res) => {
      service.status = res.statusCode === 200 ? 'healthy' : 'unhealthy';
      resolve();
    });

    req.on('error', () => {
      service.status = 'down';
      resolve();
    });

    req.on('timeout', () => {
      service.status = 'timeout';
      req.destroy();
      resolve();
    });

    req.end();
  });
}

// Main server
const server = http.createServer((req, res) => {
  // CORS
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type, Authorization');

  if (req.method === 'OPTIONS') {
    res.statusCode = 204;
    res.end();
    return;
  }

  // Health check
  if (req.url === '/health') {
    res.setHeader('Content-Type', 'application/json');
    res.end(JSON.stringify({
      status: 'ok',
      version: '0.1.0-gateway',
      services: Object.entries(services).map(([name, config]) => ({
        name,
        status: config.status,
        url: `http://${config.host}:${config.port}`,
      })),
    }));
    return;
  }

  // Route to appropriate service
  if (req.url.startsWith('/api/v1')) {
    proxyRequest(req, res, services.intelligence);
  } else {
    res.statusCode = 404;
    res.end(JSON.stringify({ error: 'Not Found', path: req.url }));
  }
});

// Check health of all services on startup
async function init() {
  console.log('🔍 Checking service health...');
  for (const [name, service] of Object.entries(services)) {
    await checkServiceHealth(name, service);
    console.log(`   ${name}: ${service.status}`);
  }

  server.listen(PORT, () => {
    console.log(`🚀 LandveX Gateway running on port ${PORT}`);
    console.log(`📡 Services:`);
    Object.entries(services).forEach(([name, config]) => {
      console.log(`   - ${name}: http://${config.host}:${config.port} (${config.status})`);
    });
  });
}

init();