// $Id$
/**
 * @file
 * TOC builder for advanced_help pages
 *  
 * @copyright Ouest Systèmes Informatiques (OSInet)
 *
 * @license Licensed under the General Public License version 2 and later.
 */

/*jslint white: true, onevar: true, undef: true, nomen: true, eqeqeq: true, 
 plusplus: true, bitwise: true, regexp: true, newcap: true, immed: true, 
 indent: 2 */
/*global $*/

/**
 * Provide an appropriate toggle message depending on TOC display state
 * 
 * @return string
 */
function ahToggleGetText(state) {
  return state ? Drupal.t('[ + ]') : Drupal.t('[ - ]');
}

/**
 * Toggle the state of the headings list and the label of the toggle text.
 * 
 * @return void
 */
function ahTocToggle() {
  var display = $('.ah-toc ul').css('display');
  
  $('.ah-toc .ah-toggle').text(ahToggleGetText(display !== 'none')); 
  $('.ah-toc ul').toggle(100);  
}

/**
 * Build a TOC div from the Hn elements in a given context
 * 
 * Extract the H[1-7] list in DOM order manually: with jQuery < 1.4,
 * neither $('h1, h2...') nor .add() return in DOM order, hence the use
 * of filter() on a * selector instead.
 * 
 * @return jQuery
 *   A list of the headings in the page
 */
function ahTocBuildToc() {

  var context,  // the context of the help page 
    elements,   // the list of headings
    element,    // one of the headings
    list,       // the string form of the toc list
    index,      // a running index for missing heading IDs
    id;         // the current id when iterating on the headings
  
  context = $('div.advanced-help-topic');
  elements = $('*', context).filter(function (index) {
    return ['H1', 'H2', 'H3', 'H4', 'H5', 'H6', 'H7'].indexOf(this.nodeName) !== -1;
  });

  /**
   * Only build the toc if there 2 headings or more in the page
   */
  if (elements.length <= 1) {
    return;
  }

  // Build the headings list
  list = "<ul>\n";
  index = 0;
  
  elements.each(function () {
    element = $(this);
    id = element.attr('id');
    if (id === '') {
      index += 1; // Avoid JSline warning on ++ use
      id = 'toc' + index;
      element.attr('id', id);
    }
    // @TODO use some form of l() instead of string concatenation
    list += '<li class="' + this.nodeName.toLowerCase() + '">' +
      '<a href="#' + id + '">' + element.text() + "</a></li>\n";
  });
  list += "</ul>\n";

  // Avoid creating multiple TOCs if this function is called several times
  $('div.ah-toc', context).remove(); 
  
  // @TODO use a theme function
  context.prepend('<div class="ah-toc"><div class="ah-toc-title">' + Drupal.t('Table of contents') + '</div></div>');
  $('div.ah-toc').append(list);
  $('<span class="ah-toggle">' + ahToggleGetText(false) + 
    '</span>').appendTo($('div.ah-toc-title')).click(ahTocToggle);
}

$(ahTocBuildToc);