/**
 * @file
 * Attaches the behaviors for the Overlay parent pages.
 */

(function ($) {

/**
 * Open the overlay, or load content into it, when an admin link is clicked.
 */
Drupal.behaviors.overlayParent = {
  attach: function (context, settings) {
    if (Drupal.overlay.isOpen) {
      Drupal.overlay.makeDocumentUntabbable(context);
    }

    if (this.processed) {
      return;
    }
    this.processed = true;

    $(window)
      // When the hash (URL fragment) changes, open the overlay if needed.
      .bind('hashchange.drupal-overlay', $.proxy(Drupal.overlay, 'eventhandlerOperateByURLFragment'))
      // Trigger the hashchange handler once, after the page is loaded, so that
      // permalinks open the overlay.
      .triggerHandler('hashchange.drupal-overlay');

    $(document)
      // Instead of binding a click event handler to every link we bind one to
      // the document and only handle events that bubble up. This allows other
      // scripts to bind their own handlers to links and also to prevent
      // overlay's handling.
      .bind('click.drupal-overlay mouseup.drupal-overlay', $.proxy(Drupal.overlay, 'eventhandlerOverrideLink'));
  }
};

/**
 * Overlay object for parent windows.
 *
 * Events
 * Overlay triggers a number of events that can be used by other scripts.
 * - drupalOverlayOpen: This event is triggered when the overlay is opened.
 * - drupalOverlayBeforeClose: This event is triggered when the overlay attempts
 *   to close. If an event handler returns false, the close will be prevented.
 * - drupalOverlayClose: This event is triggered when the overlay is closed.
 * - drupalOverlayBeforeLoad: This event is triggered right before a new URL
 *   is loaded into the overlay.
 * - drupalOverlayReady: This event is triggered when the DOM of the overlay
 *   child document is fully loaded.
 * - drupalOverlayLoad: This event is triggered when the overlay is finished
 *   loading.
 * - drupalOverlayResize: This event is triggered when the overlay is being
 *   resized to match the parent window.
 */
Drupal.overlay = Drupal.overlay || {
  isOpen: false,
  isOpening: false,
  isClosing: false,
  isLoading: false
};

Drupal.overlay.prototype = {};

/**
 * Open the overlay.
 *
 * @param url
 *   The URL of the page to open in the overlay.
 *
 * @return
 *   TRUE if the overlay was opened, FALSE otherwise.
 */
Drupal.overlay.open = function (url) {
  // Just one overlay is allowed.
  if (this.isOpen || this.isOpening) {
    return this.load(url);
  }
  this.isOpening = true;
  // Store the original document title.
  this.originalTitle = document.title;

  // Create the dialog and related DOM elements.
  this.create();

  this.isOpening = false;
  this.isOpen = true;
  $(document.documentElement).addClass('overlay-open');
  this.makeDocumentUntabbable();

  // Allow other scripts to respond to this event.
  $(document).trigger('drupalOverlayOpen');

  return this.load(url);
};

/**
 * Create the underlying markup and behaviors for the overlay.
 */
Drupal.overlay.create = function () {
  this.$container = $(Drupal.theme('overlayContainer'))
    .appendTo(document.body);

  // Overlay uses transparent iframes that cover the full parent window.
  // When the overlay is open the scrollbar of the parent window is hidden.
  // Because some browsers show a white iframe background for a short moment
  // while loading a page into an iframe, overlay uses two iframes. By loading
  // the page in a hidden (inactive) iframe the user doesn't see the white
  // background. When the page is loaded the active and inactive iframes
  // are switched.
  this.activeFrame = this.$iframeA = $(Drupal.theme('overlayElement'))
    .appendTo(this.$container);

  this.inactiveFrame = this.$iframeB = $(Drupal.theme('overlayElement'))
    .appendTo(this.$container);

  this.$iframeA.bind('load.drupal-overlay', { self: this.$iframeA[0], sibling: this.$iframeB }, $.proxy(this, 'loadChild'));
  this.$iframeB.bind('load.drupal-overlay', { self: this.$iframeB[0], sibling: this.$iframeA }, $.proxy(this, 'loadChild'));

  // Add a second class "drupal-overlay-open" to indicate these event handlers
  // should only be bound when the overlay is open.
  var eventClass = '.drupal-overlay.drupal-overlay-open';
  $(window)
    .bind('resize' + eventClass, $.proxy(this, 'eventhandlerOuterResize'));
  $(document)
    .bind('drupalOverlayLoad' + eventClass, $.proxy(this, 'eventhandlerOuterResize'))
    .bind('drupalOverlayReady' + eventClass +
          ' drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerSyncURLFragment'))
    .bind('drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerRefreshPage'))
    .bind('drupalOverlayBeforeClose' + eventClass +
          ' drupalOverlayBeforeLoad' + eventClass +
          ' drupalOverlayResize' + eventClass, $.proxy(this, 'eventhandlerDispatchEvent'));

  if ($('.overlay-displace-top, .overlay-displace-bottom').length) {
    $(document)
      .bind('drupalOverlayResize' + eventClass, $.proxy(this, 'eventhandlerAlterDisplacedElements'))
      .bind('drupalOverlayClose' + eventClass, $.proxy(this, 'eventhandlerRestoreDisplacedElements'));
  }
};

/**
 * Load the given URL into the overlay iframe.
 *
 * Use this method to change the URL being loaded in the overlay if it is
 * already open.
 *
 * @return
 *   TRUE if URL is loaded into the overlay, FALSE otherwise.
 */
Drupal.overlay.load = function (url) {
  if (!this.isOpen) {
    return false;
  }

  // Allow other scripts to respond to this event.
  $(document).trigger('drupalOverlayBeforeLoad');

  $(document.documentElement).addClass('overlay-loading');

  // The contentDocument property is not supported in IE until IE8.
  var iframeDocument = this.inactiveFrame[0].contentDocument || this.inactiveFrame[0].contentWindow.document;

  // location.replace doesn't create a history entry. location.href does.
  // In this case, we want location.replace, as we're creating the history
  // entry using URL fragments.
  iframeDocument.location.replace(url);

  return true;
};

/**
 * Close the overlay and remove markup related to it from the document.
 *
 * @return
 *   TRUE if the overlay was closed, FALSE otherwise.
 */
Drupal.overlay.close = function () {
  // Prevent double execution when close is requested more than once.
  if (!this.isOpen || this.isClosing) {
    return false;
  }

  // Allow other scripts to respond to this event.
  var event = $.Event('drupalOverlayBeforeClose');
  $(document).trigger(event);
  // If a handler returned false, the close will be prevented.
  if (event.isDefaultPrevented()) {
    return false;
  }

  this.isClosing = true;
  this.isOpen = false;
  $(document.documentElement).removeClass('overlay-open');
  // Restore the original document title.
  document.title = this.originalTitle;
  this.makeDocumentTabbable();

  // Allow other scripts to respond to this event.
  $(document).trigger('drupalOverlayClose');

  // When the iframe is still loading don't destroy it immediately but after
  // the content is loaded (see Drupal.overlay.loadChild).
  if (!this.isLoading) {
    this.destroy();
    this.isClosing = false;
  }
  return true;
};

/**
 * Destroy the overlay.
 */
Drupal.overlay.destroy = function () {
  $([document, window]).unbind('.drupal-overlay-open');
  this.$container.remove();

  this.$container = null;
  this.$iframeA = null;
  this.$iframeB = null;

  this.iframeWindow = null;
};

/**
 * Redirect the overlay parent window to the given URL.
 *
 * @param url
 *   Can be an absolute URL or a relative link to the domain root.
 */
Drupal.overlay.redirect = function (url) {
  // Create a native Link object, so we can use its object methods.
  var link = $(url.link(url)).get(0);

  // If the link is already open, force the hashchange event to simulate reload.
  if (window.location.href == link.href) {
    $(window).triggerHandler('hashchange.drupal-overlay');
  }

  window.location.href = link.href;
  return true;
};

/**
 * Bind the child window.
 *
 * Note that this function is fired earlier than Drupal.overlay.loadChild.
 */
Drupal.overlay.bindChild = function (iframeWindow, isClosing) {
  this.iframeWindow = iframeWindow;

  // We are done if the child window is closing.
  if (isClosing || this.isClosing || !this.isOpen) {
    return;
  }

  // Allow other scripts to respond to this event.
  $(document).trigger('drupalOverlayReady');
};

/**
 * Event handler: load event handler for the overlay iframe.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: load
 *   - event.currentTarget: iframe
 */
Drupal.overlay.loadChild = function (event) {
  var iframe = event.data.self;
  var iframeDocument = iframe.contentDocument || iframe.contentWindow.document;
  var iframeWindow = iframeDocument.defaultView || iframeDocument.parentWindow;
  if (iframeWindow.location == 'about:blank') {
    return;
  }

  this.isLoading = false;
  $(document.documentElement).removeClass('overlay-loading');
  event.data.sibling.removeClass('overlay-active').attr({ 'tabindex': -1 });

  // Only continue when overlay is still open and not closing.
  if (this.isOpen && !this.isClosing) {
    // And child document is an actual overlayChild.
    if (iframeWindow.Drupal && iframeWindow.Drupal.overlayChild) {
      // Replace the document title with title of iframe.
      document.title = iframeWindow.document.title;

      this.activeFrame = $(iframe)
        .addClass('overlay-active')
        // Add a title attribute to the iframe for accessibility.
        .attr('title', Drupal.t('@title dialog', { '@title': iframeWindow.jQuery('#overlay-title').text() })).removeAttr('tabindex');
      this.inactiveFrame = event.data.sibling;

      // Load an empty document into the inactive iframe.
      (this.inactiveFrame[0].contentDocument || this.inactiveFrame[0].contentWindow.document).location.replace('about:blank');

      // Move the focus to just before the "skip to main content" link inside
      // the overlay.
      this.activeFrame.focus();
      var skipLink = iframeWindow.jQuery('a:first');
      Drupal.overlay.setFocusBefore(skipLink, iframeWindow.document);

      // Allow other scripts to respond to this event.
      $(document).trigger('drupalOverlayLoad');
    }
    else {
      window.location = iframeWindow.location.href.replace(/([?&]?)render=overlay&?/g, '$1').replace(/\?$/, '');
    }
  }
  else {
    this.destroy();
  }
};

/**
 * Creates a placeholder element to receive document focus.
 *
 * Setting the document focus to a link will make it visible, even if it's a
 * "skip to main content" link that should normally be visible only when the
 * user tabs to it. This function can be used to set the document focus to
 * just before such an invisible link.
 *
 * @param $element
 *   The jQuery element that should receive focus on the next tab press.
 * @param document
 *   The iframe window element to which the placeholder should be added. The
 *   placeholder element has to be created inside the same iframe as the element
 *   it precedes, to keep IE happy. (http://bugs.jquery.com/ticket/4059)
 */
Drupal.overlay.setFocusBefore = function ($element, document) {
  // Create an anchor inside the placeholder document.
  var placeholder = document.createElement('a');
  var $placeholder = $(placeholder).addClass('element-invisible').attr('href', '#');
  // Put the placeholder where it belongs, and set the document focus to it.
  $placeholder.insertBefore($element);
  $placeholder.focus();
  // Make the placeholder disappear as soon as it loses focus, so that it
  // doesn't appear in the tab order again.
  $placeholder.one('blur', function () {
    $(this).remove();
  });
};

/**
 * Check if the given link is in the administrative section of the site.
 *
 * @param url
 *   The URL to be tested.
 *
 * @return boolean
 *   TRUE if the URL represents an administrative link, FALSE otherwise.
 */
Drupal.overlay.isAdminLink = function (url) {
  if (Drupal.overlay.isExternalLink(url)) {
    return false;
  }

  var path = this.getPath(url);

  // Turn the list of administrative paths into a regular expression.
  if (!this.adminPathRegExp) {
    var prefix = '';
    if (Drupal.settings.overlay.pathPrefixes.length) {
      // Allow path prefixes used for language negatiation followed by slash,
      // and the empty string.
      prefix = '(' + Drupal.settings.overlay.pathPrefixes.join('/|') + '/|)';
    }
    var adminPaths = '^' + prefix + '(' + Drupal.settings.overlay.paths.admin.replace(/\s+/g, '|') + ')$';
    var nonAdminPaths = '^' + prefix + '(' + Drupal.settings.overlay.paths.non_admin.replace(/\s+/g, '|') + ')$';
    adminPaths = adminPaths.replace(/\*/g, '.*');
    nonAdminPaths = nonAdminPaths.replace(/\*/g, '.*');
    this.adminPathRegExp = new RegExp(adminPaths);
    this.nonAdminPathRegExp = new RegExp(nonAdminPaths);
  }

  return this.adminPathRegExp.exec(path) && !this.nonAdminPathRegExp.exec(path);
};

/**
 * Determine whether a link is external to the site.
 *
 * @param url
 *   The URL to be tested.
 *
 * @return boolean
 *   TRUE if the URL is external to the site, FALSE otherwise.
 */
Drupal.overlay.isExternalLink = function (url) {
  var re = RegExp('^((f|ht)tps?:)?//(?!' + window.location.host + ')');
  return re.test(url);
};

/**
 * Event handler: resizes overlay according to the size of the parent window.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: any
 *   - event.currentTarget: any
 */
Drupal.overlay.eventhandlerOuterResize = function (event) {
  // Proceed only if the overlay still exists.
  if (!(this.isOpen || this.isOpening) || this.isClosing || !this.iframeWindow) {
    return;
  }

  // IE6 uses position:absolute instead of position:fixed.
  if (typeof document.body.style.maxHeight != 'string') {
    this.activeFrame.height($(window).height());
  }

  // Allow other scripts to respond to this event.
  $(document).trigger('drupalOverlayResize');
};

/**
 * Event handler: resizes displaced elements so they won't overlap the scrollbar
 * of overlay's iframe.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: any
 *   - event.currentTarget: any
 */
Drupal.overlay.eventhandlerAlterDisplacedElements = function (event) {
  // Proceed only if the overlay still exists.
  if (!(this.isOpen || this.isOpening) || this.isClosing || !this.iframeWindow) {
    return;
  }

  $(this.iframeWindow.document.body).css({
    marginTop: Drupal.overlay.getDisplacement('top'),
    marginBottom: Drupal.overlay.getDisplacement('bottom')
  })
  // IE7 isn't reflowing the document immediately.
  // @todo This might be fixed in a cleaner way.
  .addClass('overlay-trigger-reflow').removeClass('overlay-trigger-reflow');

  var documentHeight = this.iframeWindow.document.body.clientHeight;
  var documentWidth = this.iframeWindow.document.body.clientWidth;
  // IE6 doesn't support maxWidth, use width instead.
  var maxWidthName = (typeof document.body.style.maxWidth == 'string') ? 'maxWidth' : 'width';

  if (Drupal.overlay.leftSidedScrollbarOffset === undefined && $(document.documentElement).attr('dir') === 'rtl') {
    // We can't use element.clientLeft to detect whether scrollbars are placed
    // on the left side of the element when direction is set to "rtl" as most
    // browsers dont't support it correctly.
    // http://www.gtalbot.org/BugzillaSection/DocumentAllDHTMLproperties.html
    // There seems to be absolutely no way to detect whether the scrollbar
    // is on the left side in Opera; always expect scrollbar to be on the left.
    if ($.browser.opera) {
      Drupal.overlay.leftSidedScrollbarOffset = document.documentElement.clientWidth - this.iframeWindow.document.documentElement.clientWidth + this.iframeWindow.document.documentElement.clientLeft;
    }
    else if (this.iframeWindow.document.documentElement.clientLeft) {
      Drupal.overlay.leftSidedScrollbarOffset = this.iframeWindow.document.documentElement.clientLeft;
    }
    else {
      var el1 = $('<div style="direction: rtl; overflow: scroll;"></div>').appendTo(document.body);
      var el2 = $('<div></div>').appendTo(el1);
      Drupal.overlay.leftSidedScrollbarOffset = parseInt(el2[0].offsetLeft - el1[0].offsetLeft);
      el1.remove();
    }
  }

  // Consider any element that should be visible above the overlay (such as
  // a toolbar).
  $('.overlay-displace-top, .overlay-displace-bottom').each(function () {
    var data = $(this).data();
    var maxWidth = documentWidth;
    // In IE, Shadow filter makes element to overlap the scrollbar with 1px.
    if (this.filters && this.filters.length && this.filters.item('DXImageTransform.Microsoft.Shadow')) {
      maxWidth -= 1;
    }

    if (Drupal.overlay.leftSidedScrollbarOffset) {
      $(this).css('left', Drupal.overlay.leftSidedScrollbarOffset);
    }

    // Prevent displaced elements overlapping window's scrollbar.
    var currentMaxWidth = parseInt($(this).css(maxWidthName));
    if ((data.drupalOverlay && data.drupalOverlay.maxWidth) || isNaN(currentMaxWidth) || currentMaxWidth > maxWidth || currentMaxWidth <= 0) {
      $(this).css(maxWidthName, maxWidth);
      (data.drupalOverlay = data.drupalOverlay || {}).maxWidth = true;
    }

    // Use a more rigorous approach if the displaced element still overlaps
    // window's scrollbar; clip the element on the right.
    var offset = $(this).offset();
    var offsetRight = offset.left + $(this).outerWidth();
    if ((data.drupalOverlay && data.drupalOverlay.clip) || offsetRight > maxWidth) {
      if (Drupal.overlay.leftSidedScrollbarOffset) {
        $(this).css('clip', 'rect(auto, auto, ' + (documentHeight - offset.top) + 'px, ' + (Drupal.overlay.leftSidedScrollbarOffset + 2) + 'px)');
      }
      else {
        $(this).css('clip', 'rect(auto, ' + (maxWidth - offset.left) + 'px, ' + (documentHeight - offset.top) + 'px, auto)');
      }
      (data.drupalOverlay = data.drupalOverlay || {}).clip = true;
    }
  });
};

/**
 * Event handler: restores size of displaced elements as they were before
 * overlay was opened.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: any
 *   - event.currentTarget: any
 */
Drupal.overlay.eventhandlerRestoreDisplacedElements = function (event) {
  var $displacedElements = $('.overlay-displace-top, .overlay-displace-bottom');
  try {
    $displacedElements.css({ maxWidth: '', clip: '' });
  }
  // IE bug that doesn't allow unsetting style.clip (http://dev.jquery.com/ticket/6512).
  catch (err) {
    $displacedElements.attr('style', function (index, attr) {
      return attr.replace(/clip\s*:\s*rect\([^)]+\);?/i, '');
    });
  }
};

/**
 * Event handler: overrides href of administrative links to be opened in
 * the overlay.
 *
 * This click event handler should be bound to any document (for example the
 * overlay iframe) of which you want links to open in the overlay.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: click, mouseup
 *   - event.currentTarget: document
 *
 * @see Drupal.overlayChild.behaviors.addClickHandler
 */
Drupal.overlay.eventhandlerOverrideLink = function (event) {
  // In some browsers the click event isn't fired for right-clicks. Use the
  // mouseup event for right-clicks and the click event for everything else.
  if ((event.type == 'click' && event.button == 2) || (event.type == 'mouseup' && event.button != 2)) {
    return;
  }

  var $target = $(event.target);

  // Only continue if clicked target (or one of its parents) is a link.
  if (!$target.is('a')) {
    $target = $target.closest('a');
    if (!$target.length) {
      return;
    }
  }

  // Never open links in the overlay that contain the overlay-exclude class.
  if ($target.hasClass('overlay-exclude')) {
    return;
  }

  // Close the overlay when the link contains the overlay-close class.
  if ($target.hasClass('overlay-close')) {
    // Clearing the overlay URL fragment will close the overlay.
    $.bbq.removeState('overlay');
    return;
  }

  var target = $target[0];
  var href = target.href;
  // Only handle links that have an href attribute and use the HTTP(S) protocol.
  if (href != undefined && href != '' && target.protocol.match(/^https?\:/)) {
    var anchor = href.replace(target.ownerDocument.location.href, '');
    // Skip anchor links.
    if (anchor.length == 0 || anchor.charAt(0) == '#') {
      return;
    }
    // Open admin links in the overlay.
    else if (this.isAdminLink(href)) {
      // If the link contains the overlay-restore class and the overlay-context
      // state is set, also update the parent window's location.
      var parentLocation = ($target.hasClass('overlay-restore') && typeof $.bbq.getState('overlay-context') == 'string')
        ? Drupal.settings.basePath + $.bbq.getState('overlay-context')
        : null;
      href = this.fragmentizeLink($target.get(0), parentLocation);
      // Only override default behavior when left-clicking and user is not
      // pressing the ALT, CTRL, META (Command key on the Macintosh keyboard)
      // or SHIFT key.
      if (event.button == 0 && !event.altKey && !event.ctrlKey && !event.metaKey && !event.shiftKey) {
        // Redirect to a fragmentized href. This will trigger a hashchange event.
        this.redirect(href);
        // Prevent default action and further propagation of the event.
        return false;
      }
      // Otherwise alter clicked link's href. This is being picked up by
      // the default action handler.
      else {
        $target
          // Restore link's href attribute on blur or next click.
          .one('blur mousedown', { target: target, href: target.href }, function (event) { $(event.data.target).attr('href', event.data.href); })
          .attr('href', href);
      }
    }
    // Non-admin links should close the overlay and open in the main window,
    // which is the default action for a link. We only need to handle them
    // if the overlay is open and the clicked link is inside the overlay iframe.
    else if (this.isOpen && target.ownerDocument === this.iframeWindow.document) {
      // Open external links in the immediate parent of the frame, unless the
      // link already has a different target.
      if (target.hostname != window.location.hostname) {
        if (!$target.attr('target')) {
          $target.attr('target', '_parent');
        }
      }
      else {
        // Add the overlay-context state to the link, so "overlay-restore" links
        // can restore the context.
        if ($target[0].hash) {
          // Leave links with an existing fragment alone. Adding an extra
          // parameter to a link like "node/1#section-1" breaks the link.
        }
        else {
          // For links with no existing fragment, add the overlay context.
          $target.attr('href', $.param.fragment(href, { 'overlay-context': this.getPath(window.location) + window.location.search }));
        }

        // When the link has a destination query parameter and that destination
        // is an admin link we need to fragmentize it. This will make it reopen
        // in the overlay.
        var params = $.deparam.querystring(href);
        if (params.destination && this.isAdminLink(params.destination)) {
          var fragmentizedDestination = $.param.fragment(this.getPath(window.location), { overlay: params.destination });
          $target.attr('href', $.param.querystring(href, { destination: fragmentizedDestination }));
        }

        // Make the link open in the immediate parent of the frame, unless the
        // link already has a different target.
        if (!$target.attr('target')) {
          $target.attr('target', '_parent');
        }
      }
    }
  }
};

/**
 * Event handler: opens or closes the overlay based on the current URL fragment.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: hashchange
 *   - event.currentTarget: document
 */
Drupal.overlay.eventhandlerOperateByURLFragment = function (event) {
  // If we changed the hash to reflect an internal redirect in the overlay,
  // its location has already been changed, so don't do anything.
  if ($.data(window.location, window.location.href) === 'redirect') {
    $.data(window.location, window.location.href, null);
    return;
  }

  // Get the overlay URL from the current URL fragment.
  var state = $.bbq.getState('overlay');
  if (state) {
    // Append render variable, so the server side can choose the right
    // rendering and add child frame code to the page if needed.
    var url = $.param.querystring(Drupal.settings.basePath + state, { render: 'overlay' });

    this.open(url);
    this.resetActiveClass(this.getPath(Drupal.settings.basePath + state));
  }
  // If there is no overlay URL in the fragment and the overlay is (still)
  // open, close the overlay.
  else if (this.isOpen && !this.isClosing) {
    this.close();
    this.resetActiveClass(this.getPath(window.location));
  }
};

/**
 * Event handler: makes sure the internal overlay URL is reflected in the parent
 * URL fragment.
 *
 * Normally the parent URL fragment determines the overlay location. However, if
 * the overlay redirects internally, the parent doesn't get informed, and the
 * parent URL fragment will be out of date. This is a sanity check to make
 * sure we're in the right place.
 *
 * The parent URL fragment is also not updated automatically when overlay's
 * open, close or load functions are used directly (instead of through
 * eventhandlerOperateByURLFragment).
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: drupalOverlayReady, drupalOverlayClose
 *   - event.currentTarget: document
 */
Drupal.overlay.eventhandlerSyncURLFragment = function (event) {
  if (this.isOpen) {
    var expected = $.bbq.getState('overlay');
    // This is just a sanity check, so we're comparing paths, not query strings.
    if (this.getPath(Drupal.settings.basePath + expected) != this.getPath(this.iframeWindow.document.location)) {
      // There may have been a redirect inside the child overlay window that the
      // parent wasn't aware of. Update the parent URL fragment appropriately.
      var newLocation = Drupal.overlay.fragmentizeLink(this.iframeWindow.document.location);
      // Set a 'redirect' flag on the new location so the hashchange event handler
      // knows not to change the overlay's content.
      $.data(window.location, newLocation, 'redirect');
      // Use location.replace() so we don't create an extra history entry.
      window.location.replace(newLocation);
    }
  }
  else {
    $.bbq.removeState('overlay');
  }
};

/**
 * Event handler: if the child window suggested that the parent refresh on
 * close, force a page refresh.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: drupalOverlayClose
 *   - event.currentTarget: document
 */
Drupal.overlay.eventhandlerRefreshPage = function (event) {
  if (Drupal.overlay.refreshPage) {
    window.location.reload(true);
  }
};

/**
 * Event handler: dispatches events to the overlay document.
 *
 * @param event
 *   Event being triggered, with the following restrictions:
 *   - event.type: any
 *   - event.currentTarget: any
 */
Drupal.overlay.eventhandlerDispatchEvent = function (event) {
  if (this.iframeWindow && this.iframeWindow.document) {
    this.iframeWindow.jQuery(this.iframeWindow.document).trigger(event);
  }
};

/**
 * Make a regular admin link into a URL that will trigger the overlay to open.
 *
 * @param link
 *   A JavaScript Link object (i.e. an <a> element).
 * @param parentLocation
 *   (optional) URL to override the parent window's location with.
 *
 * @return
 *   A URL that will trigger the overlay (in the form
 *   /node/1#overlay=admin/config).
 */
Drupal.overlay.fragmentizeLink = function (link, parentLocation) {
  // Don't operate on links that are already overlay-ready.
  var params = $.deparam.fragment(link.href);
  if (params.overlay) {
    return link.href;
  }

  // Determine the link's original destination. Set ignorePathFromQueryString to
  // true to prevent transforming this link into a clean URL while clean URLs
  // may be disabled.
  var path = this.getPath(link, true);
  // Preserve existing query and fragment parameters in the URL, except for
  // "render=overlay" which is re-added in Drupal.overlay.eventhandlerOperateByURLFragment.
  var destination = path + link.search.replace(/&?render=overlay/, '').replace(/\?$/, '') + link.hash;

  // Assemble and return the overlay-ready link.
  return $.param.fragment(parentLocation || window.location.href, { overlay: destination });
};

/**
 * Refresh any regions of the page that are displayed outside the overlay.
 *
 * @param data
 *   An array of objects with information on the page regions to be refreshed.
 *   For each object, the key is a CSS class identifying the region to be
 *   refreshed, and the value represents the section of the Drupal $page array
 *   corresponding to this region.
 */
Drupal.overlay.refreshRegions = function (data) {
  $.each(data, function () {
    var region_info = this;
    $.each(region_info, function (regionClass) {
      var regionName = region_info[regionClass];
      var regionSelector = '.' + regionClass;
      // Allow special behaviors to detach.
      Drupal.detachBehaviors($(regionSelector));
      $.get(Drupal.settings.basePath + Drupal.settings.overlay.ajaxCallback + '/' + regionName, function (newElement) {
        $(regionSelector).replaceWith($(newElement));
        Drupal.attachBehaviors($(regionSelector), Drupal.settings);
      });
    });
  });
};

/**
 * Reset the active class on links in displaced elements according to
 * given path.
 *
 * @param activePath
 *   Path to match links against.
 */
Drupal.overlay.resetActiveClass = function(activePath) {
  var self = this;
  var windowDomain = window.location.protocol + window.location.hostname;

  $('.overlay-displace-top, .overlay-displace-bottom')
  .find('a[href]')
  // Remove active class from all links in displaced elements.
  .removeClass('active')
  // Add active class to links that match activePath.
  .each(function () {
    var linkDomain = this.protocol + this.hostname;
    var linkPath = self.getPath(this);

    // A link matches if it is part of the active trail of activePath, except
    // for frontpage links.
    if (linkDomain == windowDomain && (activePath + '/').indexOf(linkPath + '/') === 0 && (linkPath !== '' || activePath === '')) {
      $(this).addClass('active');
    }
  });
};

/**
 * Helper function to get the (corrected) Drupal path of a link.
 *
 * @param link
 *   Link object or string to get the Drupal path from.
 * @param ignorePathFromQueryString
 *   Boolean whether to ignore path from query string if path appears empty.
 *
 * @return
 *   The Drupal path.
 */
Drupal.overlay.getPath = function (link, ignorePathFromQueryString) {
  if (typeof link == 'string') {
    // Create a native Link object, so we can use its object methods.
    link = $(link.link(link)).get(0);
  }

  var path = link.pathname;
  // Ensure a leading slash on the path, omitted in some browsers.
  if (path.charAt(0) != '/') {
    path = '/' + path;
  }
  path = path.replace(new RegExp(Drupal.settings.basePath + '(?:index.php)?'), '');
  if (path == '' && !ignorePathFromQueryString) {
    // If the path appears empty, it might mean the path is represented in the
    // query string (clean URLs are not used).
    var match = new RegExp('([?&])q=(.+)([&#]|$)').exec(link.search);
    if (match && match.length == 4) {
      path = match[2];
    }
  }

  return path;
};

/**
 * Get the total displacement of given region.
 *
 * @param region
 *   Region name. Either "top" or "bottom".
 *
 * @return
 *   The total displacement of given region in pixels.
 */
Drupal.overlay.getDisplacement = function (region) {
  var displacement = 0;
  var lastDisplaced = $('.overlay-displace-' + region + ':last');
  if (lastDisplaced.length) {
    displacement = lastDisplaced.offset().top + lastDisplaced.outerHeight();

    // In modern browsers (including IE9), when box-shadow is defined, use the
    // normal height.
    var cssBoxShadowValue = lastDisplaced.css('box-shadow');
    var boxShadow = (typeof cssBoxShadowValue !== 'undefined' && cssBoxShadowValue !== 'none');
    // In IE8 and below, we use the shadow filter to apply box-shadow styles to
    // the toolbar. It adds some extra height that we need to remove.
    if (!boxShadow && /DXImageTransform\.Microsoft\.Shadow/.test(lastDisplaced.css('filter'))) {
      displacement -= lastDisplaced[0].filters.item('DXImageTransform.Microsoft.Shadow').strength;
      displacement = Math.max(0, displacement);
    }
  }
  return displacement;
};

/**
 * Makes elements outside the overlay unreachable via the tab key.
 *
 * @param context
 *   The part of the DOM that should have its tabindexes changed. Defaults to
 *   the entire page.
 */
Drupal.overlay.makeDocumentUntabbable = function (context) {
  // Manipulating tabindexes for the entire document is unacceptably slow in IE6
  // and IE7, so in those browsers, the underlying page will still be reachable
  // via the tab key. However, we still make the links within the Disable
  // message unreachable, because the same message also exists within the
  // child document. The duplicate copy in the underlying document is only for
  // assisting screen-reader users navigating the document with reading commands
  // that follow markup order rather than tab order.
  if (jQuery.browser.msie && parseInt(jQuery.browser.version, 10) < 8) {
    $('#overlay-disable-message a', context).attr('tabindex', -1);
    return;
  }

  context = context || document.body;
  var $overlay, $tabbable, $hasTabindex;

  // Determine which elements on the page already have a tabindex.
  $hasTabindex = $('[tabindex] :not(.overlay-element)', context);
  // Record the tabindex for each element, so we can restore it later.
  $hasTabindex.each(Drupal.overlay._recordTabindex);
  // Add the tabbable elements from the current context to any that we might
  // have previously recorded.
  Drupal.overlay._hasTabindex = $hasTabindex.add(Drupal.overlay._hasTabindex);

  // Set tabindex to -1 on everything outside the overlay and toolbars, so that
  // the underlying page is unreachable.

  // By default, browsers make a, area, button, input, object, select, textarea,
  // and iframe elements reachable via the tab key.
  $tabbable = $('a, area, button, input, object, select, textarea, iframe');
  // If another element (like a div) has a tabindex, it's also tabbable.
  $tabbable = $tabbable.add($hasTabindex);
  // Leave links inside the overlay and toolbars alone.
  $overlay = $('.overlay-element, #overlay-container, .overlay-displace-top, .overlay-displace-bottom').find('*');
  $tabbable = $tabbable.not($overlay);
  // We now have a list of everything in the underlying document that could
  // possibly be reachable via the tab key. Make it all unreachable.
  $tabbable.attr('tabindex', -1);
};

/**
 * Restores the original tabindex value of a group of elements.
 *
 * @param context
 *   The part of the DOM that should have its tabindexes restored. Defaults to
 *   the entire page.
 */
Drupal.overlay.makeDocumentTabbable = function (context) {
  // Manipulating tabindexes is unacceptably slow in IE6 and IE7. In those
  // browsers, the underlying page was never made unreachable via tab, so
  // there is no work to be done here.
  if (jQuery.browser.msie && parseInt(jQuery.browser.version, 10) < 8) {
    return;
  }

  var $needsTabindex;
  context = context || document.body;

  // Make the underlying document tabbable again by removing all existing
  // tabindex attributes.
  var $tabindex = $('[tabindex]', context);
  if (jQuery.browser.msie && parseInt(jQuery.browser.version, 10) < 8) {
    // removeAttr('tabindex') is broken in IE6-7, but the DOM function
    // removeAttribute works.
    var i;
    var length = $tabindex.length;
    for (i = 0; i < length; i++) {
      $tabindex[i].removeAttribute('tabIndex');
    }
  }
  else {
    $tabindex.removeAttr('tabindex');
  }

  // Restore the tabindex attributes that existed before the overlay was opened.
  $needsTabindex = $(Drupal.overlay._hasTabindex, context);
  $needsTabindex.each(Drupal.overlay._restoreTabindex);
  Drupal.overlay._hasTabindex = Drupal.overlay._hasTabindex.not($needsTabindex);
};

/**
 * Record the tabindex for an element, using $.data.
 *
 * Meant to be used as a jQuery.fn.each callback.
 */
Drupal.overlay._recordTabindex = function () {
  var $element = $(this);
  var tabindex = $(this).attr('tabindex');
  $element.data('drupalOverlayOriginalTabIndex', tabindex);
};

/**
 * Restore an element's original tabindex.
 *
 * Meant to be used as a jQuery.fn.each callback.
 */
Drupal.overlay._restoreTabindex = function () {
  var $element = $(this);
  var tabindex = $element.data('drupalOverlayOriginalTabIndex');
  $element.attr('tabindex', tabindex);
};

/**
 * Theme function to create the overlay iframe element.
 */
Drupal.theme.prototype.overlayContainer = function () {
  return '<div id="overlay-container"><div class="overlay-modal-background"></div></div>';
};

/**
 * Theme function to create an overlay iframe element.
 */
Drupal.theme.prototype.overlayElement = function (url) {
  return '<iframe class="overlay-element" frameborder="0" scrolling="auto" allowtransparency="true"></iframe>';
};

})(jQuery);