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

const PORT = process.env.PORT || 3000;
const PUBLIC_DIR = path.join(__dirname, 'public');

const MIME_TYPES = {
  '.html': 'text/html; charset=utf-8',
  '.css':  'text/css',
  '.js':   'text/javascript',
  '.png':  'image/png',
  '.jpg':  'image/jpeg',
  '.ico':  'image/x-icon',
};

function serveStatic(res, filePath) {
  fs.readFile(filePath, (err, data) => {
    if (err) {
      res.writeHead(404);
      res.end('Not Found');
      return;
    }
    const ext = path.extname(filePath);
    res.writeHead(200, { 'Content-Type': MIME_TYPES[ext] || 'application/octet-stream' });
    res.end(data);
  });
}

function sendJson(res, status, body) {
  res.writeHead(status, { 'Content-Type': 'application/json' });
  res.end(JSON.stringify(body));
}

function readBody(req) {
  return new Promise((resolve) => {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', () => {
      try { resolve(JSON.parse(body)); }
      catch { resolve({}); }
    });
  });
}

const server = http.createServer(async (req, res) => {
  const url = new URL(req.url, `http://localhost`);
  const pathname = url.pathname;

  // API routes
  if (pathname === '/api/greeting' && req.method === 'GET') {
    const greetings = ['안녕하세요! 👋', '반갑습니다! 😊', '어서오세요! 🌸', '좋은 하루예요! ☀️', '환영합니다! 🎉'];
    sendJson(res, 200, { message: greetings[Math.floor(Math.random() * greetings.length)] });
    return;
  }

  if (pathname === '/api/stats' && req.method === 'GET') {
    sendJson(res, 200, {
      uptime: Math.floor(process.uptime()),
      nodeVersion: process.version,
      platform: process.platform,
      deployedAt: new Date().toISOString(),
    });
    return;
  }

  if (pathname === '/api/echo' && req.method === 'POST') {
    const { text } = await readBody(req);
    if (!text) { sendJson(res, 400, { error: '텍스트를 입력해주세요.' }); return; }
    sendJson(res, 200, { echo: text, length: text.length });
    return;
  }

  // Static files
  const filePath = path.join(PUBLIC_DIR, pathname === '/' ? 'index.html' : pathname);
  const ext = path.extname(filePath);
  if (ext) {
    serveStatic(res, filePath);
  } else {
    serveStatic(res, path.join(PUBLIC_DIR, 'index.html'));
  }
});

server.listen(PORT, () => {
  console.log(`서버 실행 중: http://localhost:${PORT}`);
});