(function ($) {

/**

 * Toggle the visibility of a fieldset using smooth animations.

 */

Drupal.toggleFieldset = function (fieldset) {

  var $fieldset = $(fieldset);

  if ($fieldset.is('.collapsed')) {

    var $content = $('> .fieldset-wrapper', fieldset).hide();

    $fieldset

      .removeClass('collapsed')

      .trigger({ type: 'collapsed', value: false })

      .find('> legend span.fieldset-legend-prefix').html(Drupal.t('Hide'));

    $content.slideDown({

      duration: 'fast',

      easing: 'linear',

      complete: function () {

        Drupal.collapseScrollIntoView(fieldset);

        fieldset.animating = false;

      },

      step: function () {

        // Scroll the fieldset into view.

        Drupal.collapseScrollIntoView(fieldset);

      }

    });

  }

  else {

    $fieldset.trigger({ type: 'collapsed', value: true });

    $('> .fieldset-wrapper', fieldset).slideUp('fast', function () {

      $fieldset

        .addClass('collapsed')

        .find('> legend span.fieldset-legend-prefix').html(Drupal.t('Show'));

      fieldset.animating = false;

    });

  }

};

/**

 * Scroll a given fieldset into view as much as possible.

 */

Drupal.collapseScrollIntoView = function (node) {

  var h = document.documentElement.clientHeight || document.body.clientHeight || 0;

  var offset = document.documentElement.scrollTop || document.body.scrollTop || 0;

  var posY = $(node).offset().top;

  var fudge = 55;

  if (posY + node.offsetHeight + fudge > h + offset) {

    if (node.offsetHeight > h) {

      window.scrollTo(0, posY);

    }

    else {

      window.scrollTo(0, posY + node.offsetHeight - h + fudge);

    }

  }

};

Drupal.behaviors.collapse = {

  attach: function (context, settings) {

    $('fieldset.collapsible', context).once('collapse', function () {

      var $fieldset = $(this);

      // Expand fieldset 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 ($fieldset.find('.error' + anchor).length) {

        $fieldset.removeClass('collapsed');

      }

      var summary = $('<span class="summary"></span>');

      $fieldset.

        bind('summaryUpdated', function () {

          var text = $.trim($fieldset.drupalGetSummary());

          summary.html(text ? ' (' + text + ')' : '');

        })

        .trigger('summaryUpdated');

      // Turn the legend into a clickable link, but retain span.fieldset-legend

      // for CSS positioning.

      var $legend = $('> legend .fieldset-legend', this);

      $('<span class="fieldset-legend-prefix element-invisible"></span>')

        .append($fieldset.hasClass('collapsed') ? Drupal.t('Show') : Drupal.t('Hide'))

        .prependTo($legend)

        .after(' ');

      // .wrapInner() does not retain bound events.

      var $link = $('<a class="fieldset-title" href="#"></a>')

        .prepend($legend.contents())

        .appendTo($legend)

        .click(function () {

          var fieldset = $fieldset.get(0);

          // Don't animate multiple times.

          if (!fieldset.animating) {

            fieldset.animating = true;

            Drupal.toggleFieldset(fieldset);

          }

          return false;

        });

      $legend.append(summary);

    });

  }

};

})(jQuery);