/**
 * @file
 * Polyfill for HTML5 details elements.
 */

(function ($, Modernizr, Drupal) {

  'use strict';

  /**
   * The collapsible details object represents a single details element.
   *
   * @constructor Drupal.CollapsibleDetails
   *
   * @param {HTMLElement} node
   */
  function CollapsibleDetails(node) {
    this.$node = $(node);
    this.$node.data('details', this);
    // Expand details if there are errors inside, or if it contains an
    // element that is targeted by the URI fragment identifier.
    var anchor = location.hash && location.hash !== '#' ? ', ' + location.hash : '';
    if (this.$node.find('.error' + anchor).length) {
      this.$node.attr('open', true);
    }
    // Initialize and setup the summary,
    this.setupSummary();
    // Initialize and setup the legend.
    this.setupLegend();
  }

  $.extend(CollapsibleDetails, /** @lends Drupal.CollapsibleDetails */{

    /**
     * Holds references to instantiated CollapsibleDetails objects.
     *
     * @type {Array.<Drupal.CollapsibleDetails>}
     */
    instances: []
  });

  $.extend(CollapsibleDetails.prototype, /** @lends Drupal.CollapsibleDetails# */{

    /**
     * Initialize and setup summary events and markup.
     *
     * @fires event:summaryUpdated
     *
     * @listens event:summaryUpdated
     */
    setupSummary: function () {
      this.$summary = $('<span class="summary"></span>');
      this.$node
        .on('summaryUpdated', $.proxy(this.onSummaryUpdated, this))
        .trigger('summaryUpdated');
    },

    /**
     * Initialize and setup legend markup.
     */
    setupLegend: function () {
      // Turn the summary into a clickable link.
      var $legend = this.$node.find('> summary');

      $('<span class="details-summary-prefix visually-hidden"></span>')
        .append(this.$node.attr('open') ? Drupal.t('Hide') : Drupal.t('Show'))
        .prependTo($legend)
        .after(document.createTextNode(' '));

      // .wrapInner() does not retain bound events.
      $('<a class="details-title"></a>')
        .attr('href', '#' + this.$node.attr('id'))
        .prepend($legend.contents())
        .appendTo($legend);

      $legend
        .append(this.$summary)
        .on('click', $.proxy(this.onLegendClick, this));
    },

    /**
     * Handle legend clicks.
     *
     * @param {jQuery.Event} e
     */
    onLegendClick: function (e) {
      this.toggle();
      e.preventDefault();
    },

    /**
     * Update summary.
     */
    onSummaryUpdated: function () {
      var text = $.trim(this.$node.drupalGetSummary());
      this.$summary.html(text ? ' (' + text + ')' : '');
    },

    /**
     * Toggle the visibility of a details element using smooth animations.
     */
    toggle: function () {
      var isOpen = !!this.$node.attr('open');
      var $summaryPrefix = this.$node.find('> summary span.details-summary-prefix');
      if (isOpen) {
        $summaryPrefix.html(Drupal.t('Show'));
      }
      else {
        $summaryPrefix.html(Drupal.t('Hide'));
      }
      // Delay setting the attribute to emulate chrome behavior and make
      // details-aria.js work as expected with this polyfill.
      setTimeout(function () {
        this.$node.attr('open', !isOpen);
      }.bind(this), 0);
    }
  });

  /**
   * Polyfill HTML5 details element.
   *
   * @type {Drupal~behavior}
   */
  Drupal.behaviors.collapse = {
    attach: function (context) {
      if (Modernizr.details) {
        return;
      }
      var $collapsibleDetails = $(context).find('details').once('collapse').addClass('collapse-processed');
      if ($collapsibleDetails.length) {
        for (var i = 0; i < $collapsibleDetails.length; i++) {
          CollapsibleDetails.instances.push(new CollapsibleDetails($collapsibleDetails[i]));
        }
      }
    }
  };

  // Expose constructor in the public space.
  Drupal.CollapsibleDetails = CollapsibleDetails;

})(jQuery, Modernizr, Drupal);
