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 load() {
  try {
    return JSON.parse(fs.readFileSync(DATA_FILE, 'utf8'));
  } catch {
    return { items: [], log: [] };
  }
}

function save(data) {
  fs.writeFileSync(DATA_FILE, JSON.stringify(data, null, 2));
}

const server = http.createServer((req, res) => {
  const url = req.url.split('?')[0];
  const method = req.method;

  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  res.setHeader('Access-Control-Allow-Headers', 'Content-Type');

  if (method === 'OPTIONS') {
    res.writeHead(204);
    res.end();
    return;
  }

  if (url === '/api/requests' && method === 'GET') {
    const data = load();
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify(data.items));
    return;
  }

  if (url === '/api/requests' && method === 'POST') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', () => {
      const data = load();
      const newRequest = JSON.parse(body);
      newRequest.id = Date.now();
      newRequest.createdAt = new Date().toISOString();
      newRequest.updatedAt = new Date().toISOString();
      data.items.push(newRequest);
      data.log.push({
        when: new Date().toISOString(),
        what: `Создана заявка #${newRequest.id}`,
        who: newRequest.operator || 'Система'
      });
      save(data);
      res.writeHead(201, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(newRequest));
    });
    return;
  }

  if (url === '/api/requests' && method === 'PUT') {
    let body = '';
    req.on('data', chunk => { body += chunk; });
    req.on('end', () => {
      const data = load();
      const updated = JSON.parse(body);
      const index = data.items.findIndex(r => r.id === updated.id);
      if (index !== -1) {
        const old = data.items[index];
        updated.updatedAt = new Date().toISOString();
        data.items[index] = { ...old, ...updated };
        data.log.push({
          when: new Date().toISOString(),
          what: `Обновлена заявка #${updated.id}: статус ${old.status} → ${updated.status}`,
          who: updated.operator || 'Система'
        });
        save(data);
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify(updated));
      } else {
        res.writeHead(404, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify({ error: 'Заявка не найдена' }));
      }
    });
    return;
  }

  if (url.startsWith('/api/requests/') && method === 'DELETE') {
    const id = parseInt(url.split('/').pop());
    const data = load();
    const index = data.items.findIndex(r => r.id === id);
    if (index !== -1) {
      const removed = data.items.splice(index, 1)[0];
      data.log.push({
        when: new Date().toISOString(),
        what: `Удалена заявка #${id}`,
        who: 'Оператор'
      });
      save(data);
      res.writeHead(200, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify(removed));
    } else {
      res.writeHead(404, { 'Content-Type': 'application/json' });
      res.end(JSON.stringify({ error: 'Заявка не найдена' }));
    }
    return;
  }

  if (url === '/api/log' && method === 'GET') {
    const data = load();
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify(data.log.slice(-50)));
    return;
  }

  if (url === '/' || url === '/index.html') {
    const filePath = path.join(__dirname, 'index.html');
    fs.readFile(filePath, 'utf8', (err, content) => {
      if (err) {
        res.writeHead(500);
        res.end('Ошибка загрузки страницы');
        return;
      }
      res.writeHead(200, { 'Content-Type': 'text/html' });
      res.end(content);
    });
    return;
  }

  const filePath = path.join(__dirname, url);
  fs.readFile(filePath, (err, content) => {
    if (err) {
      res.writeHead(404);
      res.end('Не найдено');
      return;
    }
    const ext = path.extname(url);
    const mime = {
      '.css': 'text/css',
      '.js': 'application/javascript',
      '.png': 'image/png',
      '.svg': 'image/svg+xml'
    };
    res.writeHead(200, { 'Content-Type': mime[ext] || 'text/plain' });
    res.end(content);
  });
});

server.listen(PORT, () => {
  console.log(`Сервер заявок запущен на порту ${PORT}`);
});