/**
 * Copyright (c) 2010 The Chromium Authors. All rights reserved.  Use of this
 * source code is governed by a BSD-style license that can be found in the
 * LICENSE file.
 */

var TEXT_NODE = 3; // Text nodes have nodeType of 3.

/**
 * Toggles the display of nodes given the status of their associated controls.
 *
 * For each node passed to this function, check to see if a toggle has been
 * inserted into the node's parent.  If yes, change the state of the toggle and
 * hide/reveal the node as needed.
 *
 * @param {NodeList|Node|Array.<Node>} Nodes to operate on.
 */
function toggleList(list) {
  if (typeof list.length != 'number') {
    list = Array(list);
  }

  for (var i = 0; i < list.length; i++) {
    var toggle = list[i].parentNode &&
                 list[i].parentNode.firstChild;
    if (toggle && toggle.className.substring(0, 6) == 'toggle') {
      var visible = toggle.className == 'toggle';
      list[i].style.display = visible ? 'block' : 'none';
      toggle.className = visible ? 'toggle selected' : 'toggle';
    }
  }
};

/**
 * Reveals the hidden ancestor of the passed node, adjusts toggles as needed.
 *
 * @param {Node} node The node whose ancestor is a hidden toggleable element.
 */
function revealAncestor(node) {
  while (node.parentNode) {
    if (node.style.display == 'none') {
      toggleList(node);
      break;
    }
    node = node.parentNode;
  }
};

/**
 * Adds toggle controls to the sidebar list.
 *
 * Controls are inserted as the first children of list items in the sidebar
 * which contain only text (not a link).  Handlers are set up so that when a
 * toggle control is clicked, any <ul> elements who are siblings of the control
 * are hidden/revealed as appropriate given the control's state.
 *
 * If a list item possesses the class "leftNavSelected" its ancestor <ul> is
 * revealed by default (it represents the current page).
 */
function initToggles() {
  var toc = document.getElementById('gc-toc');
  var items = toc.getElementsByTagName('li');
  var selectedNode = null;
  for (var i = 0; i < items.length; i++) {
    var item = items[i];
    if (item.className == 'leftNavSelected') {
      selectedNode = item;
    } else if (item.firstChild &&
               item.firstChild.nodeType == TEXT_NODE) {
      // Only assign toggles to text nodes in the sidebar.
      var a = document.createElement('a');
      a.className = 'toggle selected';
      a.appendChild(document.createTextNode(' '));
      a.onclick = function() {
        toggleList(this.parentNode.getElementsByTagName('ul'));
      };
      item.insertBefore(a, item.firstChild);
      toggleList(item.getElementsByTagName('ul'));
    }
  }
  if (selectedNode) {
    revealAncestor(selectedNode);
  }
};