Как определить источник клиента в Telegram-боте при помощи UTM метки?

<script>
(function () {
  const params = new URLSearchParams(location.search);

  const src = params.get('utm_source') || '';
  const med = params.get('utm_medium') || '';
  const cmp = params.get('utm_campaign') || '';

  if (!src && !med && !cmp) return;

  const clean = (v, max) =>
    v.toString()
     .trim()
     .replace(/\s+/g,'-')
     .replace(/[^A-Za-z0-9_-]/g,'')
     .slice(0, max);

  const payload = (
    `s_${clean(src,12)}-m_${clean(med,12)}-c_${clean(cmp,24)}`
  ).slice(0,64).replace(/-$/,'');

  const buildHref = (href) => {
    try {
      const url = new URL(href);
      if (!/^(t\.me|telegram\.me)$/.test(url.hostname)) return null;

      const parts = url.pathname.split('/').filter(Boolean);
      if (!parts[0]) return null;

      return `https://t.me/${parts[0]}?start=${payload}`;
    } catch {
      return null;
    }
  };

  const updateLinks = () => {
    document.querySelectorAll('a[href*="t.me/"], a[href*="telegram.me/"]').forEach(a => {
      const newHref = buildHref(a.href);
      if (newHref && a.href !== newHref) {
        a.href = newHref;
      }
    });
  };

  updateLinks();

  const observer = new MutationObserver(updateLinks);
  observer.observe(document.body, {
    childList: true,
    subtree: true,
    attributes: true
  });
})();
</script>