(function ($) {

/**
 * Shows checked and disabled checkboxes for inherited permissions.
 */
Drupal.behaviors.permissions = {
  attach: function (context) {
    var self = this;
    $('table#permissions').once('permissions', function () {
      // On a site with many roles and permissions, this behavior initially has
      // to perform thousands of DOM manipulations to inject checkboxes and hide
      // them. By detaching the table from the DOM, all operations can be
      // performed without triggering internal layout and re-rendering processes
      // in the browser.
      var $table = $(this);
      if ($table.prev().length) {
        var $ancestor = $table.prev(), method = 'after';
      }
      else {
        var $ancestor = $table.parent(), method = 'append';
      }
      $table.detach();

      // Create dummy checkboxes. We use dummy checkboxes instead of reusing
      // the existing checkboxes here because new checkboxes don't alter the
      // submitted form. If we'd automatically check existing checkboxes, the
      // permission table would be polluted with redundant entries. This
      // is deliberate, but desirable when we automatically check them.
      var $dummy = $('<input type="checkbox" class="dummy-checkbox" disabled="disabled" checked="checked" />')
        .attr('title', Drupal.t("This permission is inherited from the authenticated user role."))
        .hide();

      $('input[type=checkbox]', this).not('.rid-2, .rid-1').addClass('real-checkbox').each(function () {
        $dummy.clone().insertAfter(this);
      });

      // Initialize the authenticated user checkbox.
      $('input[type=checkbox].rid-2', this)
        .bind('click.permissions', self.toggle)
        // .triggerHandler() cannot be used here, as it only affects the first
        // element.
        .each(self.toggle);

      // Re-insert the table into the DOM.
      $ancestor[method]($table);
    });
  },

  /**
   * Toggles all dummy checkboxes based on the checkboxes' state.
   *
   * If the "authenticated user" checkbox is checked, the checked and disabled
   * checkboxes are shown, the real checkboxes otherwise.
   */
  toggle: function () {
    var authCheckbox = this, $row = $(this).closest('tr');
    // jQuery performs too many layout calculations for .hide() and .show(),
    // leading to a major page rendering lag on sites with many roles and
    // permissions. Therefore, we toggle visibility directly.
    $row.find('.real-checkbox').each(function () {
      this.style.display = (authCheckbox.checked ? 'none' : '');
    });
    $row.find('.dummy-checkbox').each(function () {
      this.style.display = (authCheckbox.checked ? '' : 'none');
    });
  }
};

})(jQuery);