const fs = require('fs');
const path = require('path');
const jwt = require('jsonwebtoken');
const http2 = require('http2');

const TEAM_ID = 'ZZMLW32PHH';
const KEY_ID = '3VJ5X6V9Q8';
const BUNDLE_ID = 'com.shenyan.room';
const KEY_PATH = path.join(__dirname, 'AuthKey_3VJ5X6V9Q8.p8');

// cache JWT for ~50min (max 1hr)
let cachedToken = null;
let tokenExpiry = 0;

function getJWT() {
  if (cachedToken && Date.now() < tokenExpiry) return cachedToken;
  const key = fs.readFileSync(KEY_PATH, 'utf-8');
  const now = Math.floor(Date.now() / 1000);
  const payload = { iss: TEAM_ID, iat: now };
  const headers = { alg: 'ES256', kid: KEY_ID };
  cachedToken = jwt.sign(payload, key, { algorithm: 'ES256', header: headers, expiresIn: '50m' });
  tokenExpiry = now + 3000; // 50 min
  return cachedToken;
}

function sendAPNs(deviceToken, title, body) {
  return new Promise((resolve, reject) => {
    const payload = JSON.stringify({
      aps: {
        alert: { title: title || '沈晏', body: body || '' },
        sound: 'default',
        badge: 1,
      },
    });

    const client = http2.connect('https://api.sandbox.push.apple.com:443');
    client.on('error', err => reject(err));

    const req = client.request({
      ':method': 'POST',
      ':path': `/3/device/${deviceToken}`,
      'authorization': `bearer ${getJWT()}`,
      'apns-topic': BUNDLE_ID,
      'apns-push-type': 'alert',
      'apns-expiration': '0',
    });

    req.on('response', (headers) => {
      const status = headers[':status'];
      let data = '';
      req.on('data', c => data += c);
      req.on('end', () => {
        client.close();
        if (status === 200) resolve({ ok: true, status });
        else reject(new Error(`APNs ${status}: ${data}`));
      });
    });

    req.on('error', err => { client.close(); reject(err); });
    req.end(payload);
  });
}

module.exports = { sendAPNs };