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

const PORT = process.env.PORT || 3000;
const DATA_FILE = path.join(__dirname, 'data.json');

function loadData() {
  try { return JSON.parse(fs.readFileSync(DATA_FILE, 'utf8')); }
  catch (_) { return { en: [], kz: [], et: [] }; }
}
function saveData(data) {
  fs.writeFileSync(DATA_FILE, JSON.stringify(data, null, 2));
}
function parseBody(req) {
  return new Promise(resolve => {
    let s = '';
    req.on('data', chr => s += chr);
    req.on('end', () => {
      try { resolve(JSON.parse(s || '{}')); } catch (_) { resolve({}); }
    });
  });
}

http.createServer(async (req, res) => {
  const url = req.url.split('?')[0];
  // API: get terms for language
  if (req.method === 'GET' && url.startsWith('/api/terms/')) {
    const lang = url.split('/').pop();
    const data = loadData();
    const terms = data[lang] || [];
    res.writeHead(200, { 'Content-Type': 'application/json' });
    return res.end(JSON.stringify(terms));
  }
  // API: add term
  if (req.method === 'POST' && url.startsWith('/api/terms/')) {
    const lang = url.split('/').pop();
    const { term, definition } = await parseBody(req);
    const data = loadData();
    if (!data[lang]) data[lang] = [];
    data[lang].push({ id: Date.now(), term, definition });
    saveData(data);
    res.writeHead(200, { 'Content-Type': 'application/json' });
    return res.end(JSON.stringify({ ok: true }));
  }
  // Serve static files
  let filePath = url === '/' ? '/index.html' : url;
  const fullPath = path.join(__dirname, filePath);
  if (fullPath.startsWith(__dirname) && fs.existsSync(fullPath) && fs.statSync(fullPath).isFile()) {
    const ext = path.extname(fullPath);
    const mime = {
      '.html': 'text/html',
      '.css': 'text/css',
      '.js': 'application/javascript'
    }[ext] || 'application/octet-stream';
    res.writeHead(200, { 'Content-Type': mime + '; charset=utf-8' });
    return res.end(fs.readFileSync(fullPath));
  }
  res.writeHead(404);
  res.end('Not found');
}).listen(PORT, () => console.log('Server listening on port ' + PORT));