(function () {
  var form = document.getElementById('searchForm');
  var input = document.getElementById('q');
  var treeEl = document.getElementById('tree');
  var treeStatus = document.getElementById('treeStatus');
  var resultMeta = document.getElementById('resultMeta');
  var resultsEl = document.getElementById('results');

  var nodeState = new Map();
  var runningSearchId = 0;
  var HOME_SEARCH_CACHE_KEY = 'fb.home.search.q';

  function parseQuery() {
    var params = new URLSearchParams(location.search || '');
    return (params.get('q') || '').trim();
  }

  function readCachedQuery() {
    try {
      return (sessionStorage.getItem(HOME_SEARCH_CACHE_KEY) || '').trim();
    } catch (e) {
      return '';
    }
  }

  function writeCachedQuery(q) {
    try {
      sessionStorage.setItem(HOME_SEARCH_CACHE_KEY, (q || '').trim());
    } catch (e) {}
  }

  function encodePath(path) {
    var p = (path || '').replace(/^\/+|\/+$/g, '');
    if (!p) return '';
    return p.split('/').map(function (s) { return encodeURIComponent(s); }).join('/');
  }

  function fileLink(path) {
    return '/files/' + encodePath(path || '');
  }

  function apiUrl(path) {
    var p = encodePath(path || '');
    return '/api/resources/' + p;
  }

  function childPath(base, item) {
    if (item && typeof item.path === 'string' && item.path.length > 0) return item.path;
    var name = item && typeof item.name === 'string' ? item.name : '';
    if (!base) return name;
    return base + '/' + name;
  }

  function isDir(item) {
    return !!(item && (item.isDir || item.is_dir || item.dir || item.type === 'directory'));
  }

  function itemName(item) {
    return (item && (item.name || item.filename || item.basename || '')) || '';
  }

  async function getResource(path) {
    var res = await fetch(apiUrl(path), {
      credentials: 'include',
      headers: { 'Accept': 'application/json' }
    });

    if (res.status === 401) {
      location.href = '/login?redirect=' + encodeURIComponent('/search' + location.search);
      throw new Error('unauthorized');
    }
    if (!res.ok) throw new Error('HTTP ' + res.status);

    var data = await res.json();
    var items = [];
    if (Array.isArray(data && data.items)) items = data.items;
    else if (Array.isArray(data && data.children)) items = data.children;

    return items.map(function (it) {
      return {
        name: itemName(it),
        path: childPath(path || '', it),
        isDir: isDir(it),
        raw: it
      };
    }).filter(function (it) { return !!it.name; });
  }

  function makeNode(path, name, dir) {
    return { path: path || '', name: name || '/', isDir: !!dir, loaded: false, loading: false, children: [] };
  }

  function getNode(path) {
    var p = path || '';
    if (!nodeState.has(p)) {
      var name = p ? p.split('/').pop() : '/';
      nodeState.set(p, makeNode(p, name, true));
    }
    return nodeState.get(p);
  }

  async function loadNode(path) {
    var node = getNode(path);
    if (!node.isDir || node.loaded || node.loading) return node;

    node.loading = true;
    try {
      var children = await getResource(path);
      node.children = children.sort(function (a, b) {
        if (a.isDir !== b.isDir) return a.isDir ? -1 : 1;
        return a.name.localeCompare(b.name, 'zh-CN');
      });
      node.loaded = true;
    } finally {
      node.loading = false;
    }
    return node;
  }

  function renderTreeNode(node, parentUl) {
    var li = document.createElement('li');
    var row = document.createElement('div');
    row.className = 'tree-row';

    var tg = document.createElement('span');
    tg.className = 'tree-toggle';
    tg.textContent = node.isDir ? '▸' : '';

    var ic = document.createElement('span');
    ic.className = 'tree-icon';
    ic.textContent = node.isDir ? '📁' : '📄';

    var nm = document.createElement('span');
    nm.className = 'tree-name';
    nm.textContent = node.path ? node.name : '根目录';

    row.appendChild(tg);
    row.appendChild(ic);
    row.appendChild(nm);

    var childWrap = document.createElement('ul');
    childWrap.style.display = 'none';

    row.addEventListener('click', async function () {
      if (!node.isDir) {
        input.value = node.name;
        return;
      }

      var opening = childWrap.style.display === 'none';
      childWrap.style.display = opening ? 'block' : 'none';
      tg.textContent = opening ? '▾' : '▸';

      if (opening && childWrap.childElementCount === 0) {
        var children = [];
        try {
          await loadNode(node.path);
          children = getNode(node.path).children;
        } catch (e) {
          var err = document.createElement('li');
          err.className = 'hint';
          err.textContent = '加载失败: ' + (e.message || e);
          childWrap.appendChild(err);
          return;
        }

        children.forEach(function (ch) {
          var childNode = makeNode(ch.path, ch.name, ch.isDir);
          nodeState.set(ch.path, childNode);
          renderTreeNode(childNode, childWrap);
        });
      }
    });

    li.appendChild(row);
    li.appendChild(childWrap);
    parentUl.appendChild(li);
  }

  async function initTree() {
    treeStatus.textContent = '加载中...';
    treeEl.innerHTML = '';

    var root = getNode('');
    try {
      await loadNode('');
      var ul = document.createElement('ul');
      renderTreeNode(root, ul);
      treeEl.appendChild(ul);
      treeStatus.textContent = '仅显示当前账号有权限访问的目录和文件';
    } catch (e) {
      treeStatus.textContent = '文件树加载失败: ' + (e.message || e);
    }
  }

  function setResultMeta(text) {
    resultMeta.textContent = text;
  }

  function renderResults(items) {
    resultsEl.innerHTML = '';
    if (items.length === 0) {
      var empty = document.createElement('div');
      empty.className = 'hint';
      empty.textContent = '没有匹配结果';
      resultsEl.appendChild(empty);
      return;
    }

    items.forEach(function (it) {
      var box = document.createElement('div');
      box.className = 'result-item';
      var title = document.createElement('a');
      title.href = fileLink(it.path);
      title.textContent = (it.isDir ? '[目录] ' : '[文件] ') + it.name;
      var path = document.createElement('div');
      path.className = 'result-path';
      path.textContent = it.path || '/';
      box.appendChild(title);
      box.appendChild(path);
      resultsEl.appendChild(box);
    });
  }

  async function runSearch(q) {
    var id = ++runningSearchId;
    var query = (q || '').trim().toLowerCase();

    if (!query) {
      setResultMeta('输入关键字后开始搜索');
      resultsEl.innerHTML = '';
      return;
    }

    setResultMeta('搜索中...');
    var queue = [''];
    var visited = new Set();
    var matched = [];
    var scanned = 0;
    var maxNodes = 2500;

    while (queue.length > 0) {
      if (id !== runningSearchId) return;

      var current = queue.shift();
      if (visited.has(current)) continue;
      visited.add(current);

      var children = [];
      try {
        var node = await loadNode(current);
        children = node.children || [];
      } catch (e) {
        continue;
      }

      for (var i = 0; i < children.length; i += 1) {
        var it = children[i];
        scanned += 1;
        if (it.name.toLowerCase().indexOf(query) >= 0) matched.push(it);
        if (it.isDir) queue.push(it.path);
        if (scanned >= maxNodes) {
          setResultMeta('已扫描 ' + scanned + ' 项（达到上限），结果 ' + matched.length + ' 条');
          renderResults(matched);
          return;
        }
      }
    }

    setResultMeta('已扫描 ' + scanned + ' 项，结果 ' + matched.length + ' 条');
    renderResults(matched);
  }

  function syncQueryFromUrl() {
    var fromUrl = parseQuery();
    var q = fromUrl || readCachedQuery();
    input.value = q;
    if (q) {
      if (!fromUrl) {
        history.replaceState(null, '', '/search?q=' + encodeURIComponent(q));
      }
      runSearch(q);
    }
  }

  form.addEventListener('submit', function (e) {
    e.preventDefault();
    var q = (input.value || '').trim();
    writeCachedQuery(q);
    var url = '/search' + (q ? ('?q=' + encodeURIComponent(q)) : '');
    history.replaceState(null, '', url);
    runSearch(q);
  });

  input.addEventListener('keydown', function (e) {
    if (e.key === 'Escape') {
      input.value = '';
      writeCachedQuery('');
      history.replaceState(null, '', '/search');
      runSearch('');
    }
  });

  initTree();
  syncQueryFromUrl();
})();