// Tables with a header row can be re-ordered by clicking a column header.
(function () {
  function headerRow(table) {
    if (table.tHead && table.tHead.rows.length) return table.tHead.rows[table.tHead.rows.length - 1];
    var first = table.rows[0];
    if (!first || first.cells.length < 2) return null;
    for (var i = 0; i < first.cells.length; i++) if (first.cells[i].tagName !== "TH") return null;
    return first;
  }

  function value(row, col) {
    var cell = row.cells[col];
    return cell ? cell.textContent.trim() : "";
  }

  function number(text) {
    return /^[-+]?[\d.,\s]*\d[\d.,\s]*\S{0,3}$/.test(text) ? parseFloat(text.replace(/[\s,]/g, "")) : NaN;
  }

  function sort(table, head, th) {
    var col = th.cellIndex, down = th.getAttribute("aria-sort") === "ascending";
    var rows = [];
    for (var b = 0; b < table.tBodies.length; b++)
      for (var r = 0; r < table.tBodies[b].rows.length; r++)
        if (table.tBodies[b].rows[r] !== head) rows.push(table.tBodies[b].rows[r]);
    if (!rows.length) return;
    var numeric = rows.every(function (row) { var v = value(row, col); return !v || !isNaN(number(v)); });
    var compare = new Intl.Collator(undefined, { numeric: true, sensitivity: "base" }).compare;
    rows.map(function (row, i) { return { row: row, text: value(row, col), i: i }; })
      .sort(function (a, b) {
        if (!a.text || !b.text) return a.text || b.text ? (a.text ? -1 : 1) : a.i - b.i;  // empty cells last
        var d = numeric ? number(a.text) - number(b.text) : compare(a.text, b.text);
        return (down ? -d : d) || a.i - b.i;
      })
      .forEach(function (item) { rows[0].parentNode.appendChild(item.row); });
    for (var i = 0; i < head.cells.length; i++) head.cells[i].removeAttribute("aria-sort");
    th.setAttribute("aria-sort", down ? "descending" : "ascending");
  }

  document.querySelectorAll("table").forEach(function (table) {
    var head = headerRow(table);
    if (!head || table.querySelector("[rowspan], [colspan]")) return;
    table.classList.add("sortable");
    Array.prototype.forEach.call(head.cells, function (th) {
      th.tabIndex = 0;
      th.title = "Sort by this column";
      th.addEventListener("click", function () { sort(table, head, th); });
      th.addEventListener("keydown", function (e) {
        if (e.key === "Enter" || e.key === " ") { e.preventDefault(); sort(table, head, th); }
      });
    });
  });
})();