const http = require('http');

const pending = [];

function parseBody(req) {
  return new Promise((resolve, reject) => {
    let body = '';
    req.on('data', c => (body += c));
    req.on('end', () => {
      try {
        resolve(body ? JSON.parse(body) : {});
      } catch {
        reject(new Error('Invalid JSON'));
      }
    });
  });
}

const server = http.createServer(async (req, res) => {
  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(204);
    return res.end();
  }

  // POST /push/send — queue a notification
  if (req.method === 'POST' && req.url === '/push/send') {
    const { title, body } = await parseBody(req);
    const msg = {
      id: Date.now(),
      title: title || '沈晏',
      body: body || '',
      time: new Date().toISOString(),
    };
    pending.push(msg);
    res.writeHead(200, { 'Content-Type': 'application/json' });
    return res.end(JSON.stringify({ ok: true, queued: msg }));
  }

  // GET /push/poll — fetch pending messages, then clear
  if (req.method === 'GET' && req.url === '/push/poll') {
    const snapshot = [...pending];
    pending.length = 0;
    res.writeHead(200, { 'Content-Type': 'application/json' });
    return res.end(JSON.stringify({ messages: snapshot }));
  }

  res.writeHead(404);
  res.end('not found');
});

server.listen(3002, () => {
  console.log('push-broker on http://localhost:3002');
});