// glossary — hover tooltip for .gls-sym usages (prose links and MathJax \class nodes)
(function () {
  var tip = null;

  function ensureTip() {
    if (tip === null) {
      tip = document.createElement("div");
      tip.className = "gls-float";
      tip.style.display = "none";
      document.body.appendChild(tip);
    }
    return tip;
  }

  function keyOf(el) {
    if (el.dataset && el.dataset.glsKey) return el.dataset.glsKey;
    for (var i = 0; i < el.classList.length; i++) {
      var c = el.classList[i];
      if (c.indexOf("gls-key-") === 0) return c.slice(8);
    }
    return null;
  }

  function show(target) {
    var key = keyOf(target);
    if (!key) return;
    var entry = document.getElementById("gls-" + key);
    var t = ensureTip();
    if (entry) {
      // for a main entry, don't drag every property into the popup
      var node = entry.cloneNode(true);
      node.querySelectorAll(".gls-prop-entry").forEach(function (n) { n.remove(); });
      t.innerHTML = node.innerHTML;
    } else if (window.__glsData && window.__glsData[key]) {
      // entry lives on another page (book chapters render separately)
      t.innerHTML = window.__glsData[key];
    } else {
      return;
    }
    t.style.display = "block";
    if (window.MathJax && window.MathJax.typesetPromise) {
      window.MathJax.typesetPromise([t]).catch(function () {});
    }
    var r = target.getBoundingClientRect();
    var x = r.left + window.scrollX;
    var y = r.bottom + window.scrollY + 6;
    // keep it on screen horizontally
    var w = t.offsetWidth;
    var maxX = window.scrollX + document.documentElement.clientWidth - w - 12;
    t.style.left = Math.max(window.scrollX + 8, Math.min(x, maxX)) + "px";
    t.style.top = y + "px";
  }

  function hide() {
    if (tip !== null) tip.style.display = "none";
  }

  document.addEventListener("mouseover", function (e) {
    var el = e.target.closest ? e.target.closest(".gls-sym") : null;
    if (el) show(el);
  });
  document.addEventListener("mouseout", function (e) {
    var el = e.target.closest ? e.target.closest(".gls-sym") : null;
    if (el) hide();
  });
  document.addEventListener("click", hide);
  window.addEventListener("scroll", hide, { passive: true });
})();