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

const PORT = process.env.PORT || 3000;

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

http.createServer(async (req, res) => {
  // CORS
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
  
  if (req.method === 'OPTIONS') {
    res.writeHead(200);
    return res.end();
  }

  // API: AI запрос
  if (req.method === 'POST' && req.url === '/api/ai') {
    try {
      const data = await body(req);
      const aiResponse = await fetch(process.env.AI_BASE_URL + '/chat/completions', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'Authorization': 'Bearer ' + process.env.AI_API_KEY
        },
        body: JSON.stringify({
          model: process.env.AI_MODEL,
          messages: data.messages || []
        })
      });

      if (!aiResponse.ok) {
        throw new Error('AI error: ' + aiResponse.status);
      }

      const result = await aiResponse.json();
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(result));
    } catch (error) {
      res.writeHead(500, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ error: error.message }));
    }
    return;
  }

  // Статика
  let file = req.url === '/' ? '/index.html' : req.url.split('?')[0];
  const full = path.join(__dirname, file);
  
  if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
    const ext = path.extname(full);
    const type = ext === '.css' ? 'text/css' : ext === '.js' ? 'application/javascript' : 'text/html';
    res.writeHead(200, { 'Content-Type': type + '; charset=utf-8' });
    return res.end(fs.readFileSync(full));
  }

  res.writeHead(404);
  res.end('Not found');
}).listen(PORT, () => console.log('Сервер запущен на порту ' + PORT));