const http = require('http');
const fs = require('fs');
const path = require('path');

const DIST_DIR = path.join(__dirname, 'dist');

const MIME_TYPES = {
  '.html': 'text/html; charset=utf-8',
  '.js': 'text/javascript',
  '.css': 'text/css',
  '.json': 'application/json',
  '.png': 'image/png',
  '.jpg': 'image/jpeg',
  '.gif': 'image/gif',
  '.svg': 'image/svg+xml',
  '.ico': 'image/x-icon',
  '.woff': 'font/woff',
  '.woff2': 'font/woff2',
  '.ttf': 'font/ttf',
  '.xlsx': 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
};

function proxyToBackend(req, res) {
  const options = {
    hostname: '127.0.0.1',
    port: 8000,
    path: req.url,
    method: req.method,
    headers: { ...req.headers, host: '127.0.0.1:8000' },
  };
  const proxyReq = http.request(options, (proxyRes) => {
    res.writeHead(proxyRes.statusCode, proxyRes.headers);
    proxyRes.pipe(res, { end: true });
  });
  proxyReq.on('error', (err) => {
    console.error('Backend error:', err.message);
    res.writeHead(502, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({ error: 'Backend unavailable' }));
  });
  req.pipe(proxyReq, { end: true });
}

function serveStatic(req, res) {
  let urlPath = req.url.split('?')[0];
  let filePath = path.join(DIST_DIR, urlPath === '/' ? 'index.html' : urlPath);
  const ext = path.extname(filePath).toLowerCase();

  fs.stat(filePath, (err, stats) => {
    if (!err && stats.isFile()) {
      const contentType = MIME_TYPES[ext] || 'application/octet-stream';
      res.writeHead(200, { 'Content-Type': contentType });
      fs.createReadStream(filePath).pipe(res);
    } else {
      // SPA fallback
      const indexPath = path.join(DIST_DIR, 'index.html');
      fs.readFile(indexPath, (indexErr, data) => {
        if (indexErr) {
          res.writeHead(404);
          res.end('Not Found');
        } else {
          res.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' });
          res.end(data);
        }
      });
    }
  });
}

const server = http.createServer((req, res) => {
  if (req.url.startsWith('/api/') || req.url.startsWith('/docs') || req.url === '/openapi.json') {
    proxyToBackend(req, res);
  } else {
    serveStatic(req, res);
  }
});

const PORT = process.env.PORT || 3000;
server.listen(PORT, () => {
  console.log('DAK Portal running on port ' + PORT);
});