// Runs on DOMContentLoaded for a full page load, and right away when this
// script arrives with a boosted navigation (the document is loaded then).
(function () {
  function run() {
    var content = document.querySelector("main");
    if (!content) return;

    var headings = content.querySelectorAll("h2, h3, h4");
    if (headings.length < 2) return;

    var nav = document.createElement("nav");
    nav.className = "toc panel";

    var header = document.createElement("div");
    header.className = "panel-header";
    header.textContent = "Contents";
    nav.appendChild(header);

    var list = document.createElement("ul");
    headings.forEach(function (h) {
      if (!h.id) return;
      var li = document.createElement("li");
      li.className = "toc-" + h.tagName.toLowerCase();
      var a = document.createElement("a");
      a.href = "#" + h.id;
      var clone = h.cloneNode(true);
      clone.querySelectorAll(".btn, .muted, .dropdown").forEach(function (el) { el.remove(); });
      a.textContent = clone.textContent.trim();
      li.appendChild(a);
      list.appendChild(li);
    });
    nav.appendChild(list);

    content.insertBefore(nav, content.firstChild);
  }
  if (document.readyState === "loading") document.addEventListener("DOMContentLoaded", run);
  else run();
})();