telegram-cf-worker-ping.js

addEventListener('scheduled', event => {
  event.waitUntil(
    handleSchedule(event.scheduledTime)
  )
})

function sendMessage(chat_id, text, options = { }) {
  return fetch(`https://api.telegram.org/bot${BOT_TOKEN}/sendMessage`, {
    method: "POST",
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(Object.assign(options, { chat_id, text }))
  });
}

function fetchWithTimeout(url, timeout = 3000) {
  const controller = new AbortController();
  const id = setTimeout(() => controller.abort(), timeout);
  return fetch(url, { signal: controller.signal })
          .catch((err) => {
            if (err instanceof DOMException) {
              return ({ ok: false, status: 408, statusText: 'Request Timeout' });
            }

            else throw err;
          })
          .finally(() => clearTimeout(id));
}

// Send to Kiwidiag
function broadcast(text, options) {
  return sendMessage(CHANNEL_ID, text, options);
}

function plural(n, word) {
  return n + ' ' +(n > 1 ? word + 's' : word);
}

// https://stackoverflow.com/a/11486026/4111143
function fancyTimeFormat(duration) {   
  // Hours, minutes and seconds
  const hrs = ~~(duration / 3600);
  const mins = ~~((duration % 3600) / 60);
  const secs = ~~duration % 60;

  if (hrs > 0) {
    return plural(hrs, 'hour') + ' and ' + plural(mins, 'minute');
  }

  if (mins > 0) {
    return plural(mins, 'minute') + ' and ' + plural(secs, 'second')
  }

  return plural(secs, 'second');
}

async function getText(date, key, response) {
  const prev = await kv.get(key);

  if (response.ok) {
    const downtime = fancyTimeFormat((date - prev) / 1000);
    await kv.delete(key);
    return prev ? `✅ ${key} is up. It was down for ${downtime}` : null;
  }

  else if (prev) {
    return null;
  }

  await kv.put(key, String(date));

  return `⚠️ ${key} is down: ${response.statusText} (${response.status})`;
}

async function handleSchedule(date) {
  const [client, server] = await Promise.all([
    fetchWithTimeout('https://kiwidiag.arq.pw/sitemap.xml'),
    fetchWithTimeout('https://kiwidiag.arq.pw/api/status')
  ]);

  const clientText = await getText(date, 'Angular', client);
  const serverText = await getText(date, 'API', server);
  const texts = [clientText, serverText].filter(e => !!e);
  if (texts.length) {
    await broadcast(texts.join('\n'));
  }
}