(function () {
  var BAR_ID = 'fb-inline-search';

  function q(sel, root) { return (root || document).querySelector(sel); }
  function qa(sel, root) { return Array.from((root || document).querySelectorAll(sel)); }

  function ensureBar() {
    var bar = q('#' + BAR_ID);
    if (bar) return bar;

    bar = document.createElement('div');
    bar.id = BAR_ID;
    bar.innerHTML = '' +
      '<input id="fb-inline-search-input" type="text" autocomplete="off" placeholder="筛选当前目录文件（Ctrl+F）" />' +
      '<button class="fb-clear" type="button" title="清空">×</button>' +
      '<span class="fb-count"></span>';

    document.body.appendChild(bar);

    var input = q('#fb-inline-search-input', bar);
    var clearBtn = q('.fb-clear', bar);

    input.addEventListener('input', applyFilter);
    input.addEventListener('keydown', function (e) {
      if (e.key === 'Escape') {
        input.value = '';
        applyFilter();
      }
    });

    clearBtn.addEventListener('click', function () {
      input.value = '';
      applyFilter();
      input.focus();
    });

    return bar;
  }

  function getItems() {
    var nodes = qa('#listing .item, #listing [data-type], #listing tr, #listing li');
    var seen = new Set();
    return nodes.filter(function (el) {
      if (!el || seen.has(el)) return false;
      seen.add(el);
      return !!(el.querySelector('.name') || el.getAttribute('data-type') || (el.textContent || '').trim());
    });
  }

  function getName(el) {
    var n = q('.name', el);
    if (n && n.textContent) return n.textContent.trim();
    var a = q('a', el);
    if (a && a.textContent) return a.textContent.trim();
    return (el.textContent || '').trim();
  }

  function setVisible(el, show) {
    if (show) {
      if (el.dataset.fbOrigDisplay !== undefined) {
        el.style.display = el.dataset.fbOrigDisplay;
        delete el.dataset.fbOrigDisplay;
      } else {
        el.style.removeProperty('display');
      }
      el.removeAttribute('data-fb-hidden');
      return;
    }

    if (el.dataset.fbOrigDisplay === undefined) {
      el.dataset.fbOrigDisplay = el.style.display || '';
    }
    el.style.display = 'none';
    el.setAttribute('data-fb-hidden', '1');
  }

  function applyFilter() {
    var bar = ensureBar();
    var input = q('#fb-inline-search-input', bar);
    var count = q('.fb-count', bar);
    var query = (input.value || '').trim().toLowerCase();

    var items = getItems();
    var shown = 0;

    items.forEach(function (el) {
      var ok = !query || getName(el).toLowerCase().indexOf(query) !== -1;
      setVisible(el, ok);
      if (ok) shown += 1;
    });

    count.textContent = query ? (shown + '/' + items.length) : '';
  }

  function focusSearch() {
    var input = q('#fb-inline-search-input') || q('#fb-inline-search-input', ensureBar());
    if (!input) return;
    input.focus();
    input.select();
  }

  function intercept(evt) {
    var ctrlF = evt.type === 'keydown' && (evt.ctrlKey || evt.metaKey) && (evt.key === 'f' || evt.key === 'F');
    var btn = evt.type === 'click' && evt.target && evt.target.closest && evt.target.closest('.search-button');
    if (!ctrlF && !btn) return;

    evt.preventDefault();
    evt.stopPropagation();
    if (evt.stopImmediatePropagation) evt.stopImmediatePropagation();

    ensureBar();
    focusSearch();
  }

  function closeNativeSearch() {
    var nativeSearch = q('#search');
    if (!nativeSearch) return;
    nativeSearch.classList.remove('active', 'ongoing');
    nativeSearch.style.display = 'none';
    document.body.style.overflow = 'auto';
  }

  function bootstrap() {
    ensureBar();
    closeNativeSearch();
    applyFilter();
  }

  window.addEventListener('keydown', intercept, true);
  window.addEventListener('click', intercept, true);

  var mo = new MutationObserver(function () {
    closeNativeSearch();
    if (q('#fb-inline-search-input') && q('#fb-inline-search-input').value) applyFilter();
  });

  bootstrap();
  mo.observe(document.documentElement, { childList: true, subtree: true });
})();