/**
 * @file
 * Attaches behaviors for the Tour module's toolbar tab.
 */

(function ($, Backbone, Drupal, document) {

  "use strict";

  var queryString = decodeURI(window.location.search);

  /**
   * Attaches the tour's toolbar tab behavior.
   *
   * It uses the query string for:
   * - tour: When ?tour=1 is present, the tour will start automatically
   *         after the page has loaded.
   * - tips: Pass ?tips=class in the url to filter the available tips to
   *         the subset which match the given class.
   *
   * Example:
   *   http://example.com/foo?tour=1&tips=bar
   */
  Drupal.behaviors.tour = {
    attach: function (context) {
      $('body').once('tour', function (index, element) {
        var model = new Drupal.tour.models.StateModel();
        new Drupal.tour.views.ToggleTourView({
          el: $(context).find('#toolbar-tab-tour'),
          model: model
        });

        model
          // Allow other scripts to respond to tour events.
          .on('change:isActive', function (model, isActive) {
            $(document).trigger((isActive) ? 'drupalTourStarted' : 'drupalTourStopped');
          })
          // Initialization: check whether a tour is available on the current page.
          .set('tour', $(context).find('ol#tour'));

        // Start the tour immediately if toggled via query string.
        if (/tour=?/i.test(queryString)) {
          model.set('isActive', true);
        }

      });
    }
  };

  Drupal.tour = Drupal.tour || {models: {}, views: {}};

  /**
   * Backbone Model for tours.
   */
  Drupal.tour.models.StateModel = Backbone.Model.extend({
    defaults: {
      // Indicates whether the Drupal root window has a tour.
      tour: [],
      // Indicates whether the tour is currently running.
      isActive: false,
      // Indicates which tour is the active one (necessary to cleanly stop).
      activeTour: []
    }
  });

  /**
   * Handles edit mode toggle interactions.
   */
  Drupal.tour.views.ToggleTourView = Backbone.View.extend({

    events: {'click': 'onClick'},

    /**
     * Implements Backbone Views' initialize().
     */
    initialize: function () {
      this.listenTo(this.model, 'change:tour change:isActive', this.render);
      this.listenTo(this.model, 'change:isActive', this.toggleTour);
    },

    /**
     * Implements Backbone Views' render().
     */
    render: function () {
      // Render the visibility.
      this.$el.toggleClass('hidden', this._getTour().length === 0);
      // Render the state.
      var isActive = this.model.get('isActive');
      this.$el.find('button')
        .toggleClass('active', isActive)
        .prop('aria-pressed', isActive);
      return this;
    },

    /**
     * Model change handler; starts or stops the tour.
     */
    toggleTour: function () {
      if (this.model.get('isActive')) {
        var $tour = this._getTour();
        this._removeIrrelevantTourItems($tour, this._getDocument());
        var that = this;
        if ($tour.find('li').length) {
          $tour.joyride({
            autoStart: true,
            postRideCallback: function () { that.model.set('isActive', false); },
            template: { // HTML segments for tip layout
              link: '<a href=\"#close\" class=\"joyride-close-tip\">&times;</a>',
              button: '<a href=\"#\" class=\"button button--primary joyride-next-tip\"></a>'
            }
          });
          this.model.set({isActive: true, activeTour: $tour});
        }
      }
      else {
        this.model.get('activeTour').joyride('destroy');
        this.model.set({isActive: false, activeTour: []});
      }
    },

    /**
     * Toolbar tab click event handler; toggles isActive.
     */
    onClick: function (event) {
      this.model.set('isActive', !this.model.get('isActive'));
      event.preventDefault();
      event.stopPropagation();
    },

    /**
     * Gets the tour.
     *
     * @return jQuery
     *   A jQuery element pointing to a <ol> containing tour items.
     */
    _getTour: function () {
      return this.model.get('tour');
    },

    /**
     * Gets the relevant document as a jQuery element.
     *
     * @return jQuery
     *   A jQuery element pointing to the document within which a tour would be
     *   started given the current state.
     */
    _getDocument: function () {
      return $(document);
    },

    /**
     * Removes tour items for elements that don't have matching page elements or
     * are explicitly filtered out via the 'tips' query string.
     *
     * Example:
     *   http://example.com/foo?tips=bar
     *
     *   The above will filter out tips that do not have a matching page element or
     *   don't have the "bar" class.
     *
     * @param jQuery $tour
     *   A jQuery element pointing to a <ol> containing tour items.
     * @param jQuery $document
     *   A jQuery element pointing to the document within which the elements
     *   should be sought.
     *
     * @see _getDocument()
     */
    _removeIrrelevantTourItems: function ($tour, $document) {
      var removals = false;
      var tips = /tips=([^&]+)/.exec(queryString);
      $tour
        .find('li')
        .each(function () {
          var $this = $(this);
          var itemId = $this.attr('data-id');
          var itemClass = $this.attr('data-class');
          // If the query parameter 'tips' is set, remove all tips that don't
          // have the matching class.
          if (tips && !$(this).hasClass(tips[1])) {
            removals = true;
            $this.remove();
            return;
          }
          // Remove tip from the DOM if there is no corresponding page element.
          if ((!itemId && !itemClass) ||
            (itemId && $document.find('#' + itemId).length) ||
            (itemClass && $document.find('.' + itemClass).length)) {
            return;
          }
          removals = true;
          $this.remove();
        });

      // If there were removals, we'll have to do some clean-up.
      if (removals) {
        var total = $tour.find('li').length;
        if (!total) {
          this.model.set({tour: []});
        }

        $tour
          .find('li')
          // Rebuild the progress data.
          .each(function (index) {
            var progress = Drupal.t('!tour_item of !total', {'!tour_item': index + 1, '!total': total});
            $(this).find('.tour-progress').text(progress);
          })
          // Update the last item to have "End tour" as the button.
          .last()
          .attr('data-text', Drupal.t('End tour'));
      }
    }

  });

})(jQuery, Backbone, Drupal, document);