/**
 * gateway.js — Standalone dev server for game-justic2
 *
 * เสิร์ฟทุกไฟล์ใน project นี้เป็น "site root" (เพราะ client ใช้
 * absolute path เช่น /Login/, /Main-Lobby/, /Game/, /realtimechat/)
 * และ proxy ทราฟฟิก HTTP+WebSocket ไปยัง Node game/chat servers:
 *   - /Game/*         → 127.0.0.1:GAME_PORT (default 3004)
 *   - /realtimechat/* → 127.0.0.1:CHAT_PORT (default 3003)
 *
 * ใช้งาน:    node gateway.js
 * เปิดเว็บ:  http://localhost:8080/   (เด้งไป /Login/ อัตโนมัติ)
 *
 * ตั้งค่า port ผ่าน env:
 *   set GATEWAY_PORT=80   (ต้องปิด WAMP/Apache ก่อน)
 *   set GAME_PORT=3004
 *   set CHAT_PORT=3003
 */

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

const GATEWAY_PORT = Number(process.env.GATEWAY_PORT) || 8080;
const GAME_PORT    = Number(process.env.GAME_PORT)    || 3004;
const CHAT_PORT    = Number(process.env.CHAT_PORT)    || 3003;
const PROJECT_DIR  = __dirname;

/* ---- MIME types ---- */
const MIME = {
  '.html': 'text/html; charset=utf-8',
  '.css':  'text/css; charset=utf-8',
  '.js':   'application/javascript; charset=utf-8',
  '.mjs':  'application/javascript; charset=utf-8',
  '.json': 'application/json; charset=utf-8',
  '.png':  'image/png',
  '.jpg':  'image/jpeg',
  '.jpeg': 'image/jpeg',
  '.gif':  'image/gif',
  '.svg':  'image/svg+xml',
  '.ico':  'image/x-icon',
  '.webp': 'image/webp',
  '.woff': 'font/woff',
  '.woff2':'font/woff2',
  '.ttf':  'font/ttf',
  '.otf':  'font/otf',
  '.mp3':  'audio/mpeg',
  '.ogg':  'audio/ogg',
  '.wav':  'audio/wav',
  '.mp4':  'video/mp4',
  '.webm': 'video/webm',
  '.txt':  'text/plain; charset=utf-8',
  '.map':  'application/json; charset=utf-8',
};

/* ---- HTTP proxy helper ---- */
function proxyHttp(targetPort, targetPath, req, res) {
  const opts = {
    hostname: '127.0.0.1',
    port: targetPort,
    path: targetPath,
    method: req.method,
    headers: Object.assign({}, req.headers, { host: '127.0.0.1:' + targetPort }),
  };
  const proxy = http.request(opts, (upstream) => {
    res.writeHead(upstream.statusCode, upstream.headers);
    upstream.pipe(res, { end: true });
  });
  proxy.on('error', () => {
    res.writeHead(502, { 'Content-Type': 'text/plain; charset=utf-8' });
    res.end('Backend not running on port ' + targetPort);
  });
  req.pipe(proxy, { end: true });
}

/* ---- Static file server ---- */
function serveStatic(urlPath, res) {
  let rel = decodeURIComponent(urlPath);
  if (!rel || rel === '/') rel = '/index.html';
  if (rel.includes('..')) {
    res.writeHead(403);
    return res.end('Forbidden');
  }
  const fsPath = path.join(PROJECT_DIR, rel);
  try {
    if (fs.statSync(fsPath).isDirectory()) {
      const idx = path.join(fsPath, 'index.html');
      if (fs.existsSync(idx)) return serveFile(idx, res);
    }
  } catch (_) { /* not a dir */ }
  serveFile(fsPath, res);
}

function serveFile(fsPath, res) {
  fs.readFile(fsPath, (err, data) => {
    if (err) {
      res.writeHead(404, { 'Content-Type': 'text/plain; charset=utf-8' });
      return res.end('404 Not Found: ' + fsPath);
    }
    const ext = path.extname(fsPath).toLowerCase();
    res.writeHead(200, {
      'Content-Type': MIME[ext] || 'application/octet-stream',
      'Cache-Control': 'no-cache',
    });
    res.end(data);
  });
}

/* ---- HTTP request handler ---- */
const server = http.createServer((req, res) => {
  const urlNoQs = (req.url || '/').split('?')[0];

  // ALL /Game/* → Node Game server (3004)
  if (urlNoQs.startsWith('/Game/') || urlNoQs === '/Game') {
    return proxyHttp(GAME_PORT, req.url, req, res);
  }

  // ALL /realtimechat/* → Node Chat server (3003)
  if (urlNoQs.startsWith('/realtimechat/') || urlNoQs === '/realtimechat') {
    return proxyHttp(CHAT_PORT, req.url, req, res);
  }

  // Gateway ไม่รัน PHP — เตือนชัดเจนแทนที่จะส่งไฟล์ดิบ
  if (urlNoQs.toLowerCase().endsWith('.php')) {
    res.writeHead(501, { 'Content-Type': 'text/plain; charset=utf-8' });
    return res.end(
      'PHP ไม่ถูกประมวลผลใน gateway นี้\n' +
      'หากต้องการใช้ /Admin/ หรือ OAuth → เปิด WAMP/Apache แยก\n' +
      'URL: ' + urlNoQs
    );
  }

  // ไฟล์ที่เหลือ (Login, Main-Lobby, Main-Menu, Create Room, Loading, Quiz-Battle, ...)
  serveStatic(urlNoQs, res);
});

/* ---- WebSocket upgrade handler (สำหรับ socket.io) ---- */
server.on('upgrade', (req, socket, head) => {
  const url = req.url || '';
  let targetPort = null;

  if (url.startsWith('/Game/')) targetPort = GAME_PORT;
  else if (url.startsWith('/realtimechat/')) targetPort = CHAT_PORT;

  if (!targetPort) {
    socket.destroy();
    return;
  }

  const proxy = net.connect(targetPort, '127.0.0.1', () => {
    const reqLine = req.method + ' ' + url + ' HTTP/' + req.httpVersion + '\r\n';
    const headers = Object.assign({}, req.headers, { host: '127.0.0.1:' + targetPort });
    let headerStr = '';
    for (const [k, v] of Object.entries(headers)) {
      headerStr += k + ': ' + v + '\r\n';
    }
    proxy.write(reqLine + headerStr + '\r\n');
    if (head && head.length) proxy.write(head);
    proxy.pipe(socket, { end: true });
    socket.pipe(proxy, { end: true });
  });

  proxy.on('error', () => socket.destroy());
  socket.on('error', () => proxy.destroy());
});

server.listen(GATEWAY_PORT, () => {
  console.log('');
  console.log('  ==========================================');
  console.log('   game-justic2 Gateway');
  console.log('   http://localhost:' + GATEWAY_PORT + '/');
  console.log('  ==========================================');
  console.log('   Game (HTTP+WS) -> http://127.0.0.1:' + GAME_PORT);
  console.log('   Chat (HTTP+WS) -> http://127.0.0.1:' + CHAT_PORT);
  console.log('  ==========================================');
  console.log('');
});