// Live updates for the overview: refetches the dashboard part of the page
// (rendered by the server, like the page itself) and switches time ranges
// without a reload. Without JavaScript the page and its links still work.
(function () {
  "use strict";
  const root = document.getElementById("dashboard");
  if (!root) return;
  let range = root.dataset.range;
  let interval = Number(root.dataset.interval) || 5;
  let timer = null;

  async function refresh() {
    try {
      const r = await fetch("/dashboard?range=" + encodeURIComponent(range), { credentials: "same-origin" });
      if (r.redirected || r.status === 401 || r.status === 403) {
        location.href = "/login"; // the session ended
        return;
      }
      if (r.ok) root.innerHTML = await r.text();
    } catch (e) {
      // The router may be restarting the UI (an apply); try again later.
    }
    schedule();
  }

  function schedule() {
    clearTimeout(timer);
    if (!document.hidden) timer = setTimeout(refresh, interval * 1000);
  }

  root.addEventListener("click", function (ev) {
    const a = ev.target.closest("a[data-range]");
    if (!a) return;
    ev.preventDefault();
    range = a.dataset.range;
    interval = range === "15m" || range === "1h" ? 5 : 60;
    history.replaceState(null, "", "/?range=" + encodeURIComponent(range));
    refresh();
  });
  document.addEventListener("visibilitychange", function () {
    if (document.hidden) clearTimeout(timer);
    else refresh();
  });
  schedule();
})();