/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

this.EXPORTED_SYMBOLS = ["PopupNotifications"];

var Cc = Components.classes, Ci = Components.interfaces;

Components.utils.import("resource://gre/modules/Services.jsm");

const NOTIFICATION_EVENT_DISMISSED = "dismissed";
const NOTIFICATION_EVENT_REMOVED = "removed";
const NOTIFICATION_EVENT_SHOWING = "showing";
const NOTIFICATION_EVENT_SHOWN = "shown";

const ICON_SELECTOR = ".notification-anchor-icon";
const ICON_ATTRIBUTE_SHOWING = "showing";

const PREF_SECURITY_DELAY = "security.notification_enable_delay";

let popupNotificationsMap = new WeakMap();
let gNotificationParents = new WeakMap;

function getAnchorFromBrowser(aBrowser) {
  let anchor = aBrowser.getAttribute("popupnotificationanchor") ||
                aBrowser.popupnotificationanchor;
  if (anchor) {
    if (anchor instanceof Ci.nsIDOMXULElement) {
      return anchor;
    }
    return aBrowser.ownerDocument.getElementById(anchor);
  }
  return null;
}

/**
 * Notification object describes a single popup notification.
 *
 * @see PopupNotifications.show()
 */
function Notification(id, message, anchorID, mainAction, secondaryActions,
                      browser, owner, options) {
  this.id = id;
  this.message = message;
  this.anchorID = anchorID;
  this.mainAction = mainAction;
  this.secondaryActions = secondaryActions || [];
  this.browser = browser;
  this.owner = owner;
  this.options = options || {};
}

Notification.prototype = {

  id: null,
  message: null,
  anchorID: null,
  mainAction: null,
  secondaryActions: null,
  browser: null,
  owner: null,
  options: null,
  timeShown: null,

  /**
   * Removes the notification and updates the popup accordingly if needed.
   */
  remove: function Notification_remove() {
    this.owner.remove(this);
  },

  get anchorElement() {
    let iconBox = this.owner.iconBox;

    let anchorElement = getAnchorFromBrowser(this.browser);

    if (!iconBox)
      return anchorElement;

    if (!anchorElement && this.anchorID)
      anchorElement = iconBox.querySelector("#"+this.anchorID);

    // Use a default anchor icon if it's available
    if (!anchorElement)
      anchorElement = iconBox.querySelector("#default-notification-icon") ||
                      iconBox;

    return anchorElement;
  },

  reshow: function() {
    this.owner._reshowNotifications(this.anchorElement, this.browser);
  }
};

/**
 * The PopupNotifications object manages popup notifications for a given browser
 * window.
 * @param tabbrowser
 *        window's <xul:tabbrowser/>. Used to observe tab switching events and
 *        for determining the active browser element.
 * @param panel
 *        The <xul:panel/> element to use for notifications. The panel is
 *        populated with <popupnotification> children and displayed it as
 *        needed.
 * @param iconBox
 *        Reference to a container element that should be hidden or
 *        unhidden when notifications are hidden or shown. It should be the
 *        parent of anchor elements whose IDs are passed to show().
 *        It is used as a fallback popup anchor if notifications specify
 *        invalid or non-existent anchor IDs.
 */
this.PopupNotifications = function PopupNotifications(tabbrowser, panel, iconBox) {
  if (!(tabbrowser instanceof Ci.nsIDOMXULElement))
    throw "Invalid tabbrowser";
  if (iconBox && !(iconBox instanceof Ci.nsIDOMXULElement))
    throw "Invalid iconBox";
  if (!(panel instanceof Ci.nsIDOMXULElement))
    throw "Invalid panel";

  this.window = tabbrowser.ownerDocument.defaultView;
  this.panel = panel;
  this.tabbrowser = tabbrowser;
  this.iconBox = iconBox;
  this.buttonDelay = Services.prefs.getIntPref(PREF_SECURITY_DELAY);

  this.panel.addEventListener("popuphidden", this, true);

  this.window.addEventListener("activate", this, true);
  if (this.tabbrowser.tabContainer)
    this.tabbrowser.tabContainer.addEventListener("TabSelect", this, true);
}

PopupNotifications.prototype = {

  window: null,
  panel: null,
  tabbrowser: null,

  _iconBox: null,
  set iconBox(iconBox) {
    // Remove the listeners on the old iconBox, if needed
    if (this._iconBox) {
      this._iconBox.removeEventListener("click", this, false);
      this._iconBox.removeEventListener("keypress", this, false);
    }
    this._iconBox = iconBox;
    if (iconBox) {
      iconBox.addEventListener("click", this, false);
      iconBox.addEventListener("keypress", this, false);
    }
  },
  get iconBox() {
    return this._iconBox;
  },

  /**
   * Retrieve a Notification object associated with the browser/ID pair.
   * @param id
   *        The Notification ID to search for.
   * @param browser
   *        The browser whose notifications should be searched. If null, the
   *        currently selected browser's notifications will be searched.
   *
   * @returns the corresponding Notification object, or null if no such
   *          notification exists.
   */
  getNotification: function PopupNotifications_getNotification(id, browser) {
    let n = null;
    let notifications = this._getNotificationsForBrowser(browser || this.tabbrowser.selectedBrowser);
    notifications.some(function(x) x.id == id && (n = x));
    return n;
  },

  /**
   * Adds a new popup notification.
   * @param browser
   *        The <xul:browser> element associated with the notification. Must not
   *        be null.
   * @param id
   *        A unique ID that identifies the type of notification (e.g.
   *        "geolocation"). Only one notification with a given ID can be visible
   *        at a time. If a notification already exists with the given ID, it
   *        will be replaced.
   * @param message
   *        The text to be displayed in the notification.
   * @param anchorID
   *        The ID of the element that should be used as this notification
   *        popup's anchor. May be null, in which case the notification will be
   *        anchored to the iconBox.
   * @param mainAction
   *        A JavaScript object literal describing the notification button's
   *        action. If present, it must have the following properties:
   *          - label (string): the button's label.
   *          - accessKey (string): the button's accessKey.
   *          - callback (function): a callback to be invoked when the button is
   *            pressed.
   *        If null, the notification will not have a button, and
   *        secondaryActions will be ignored.
   * @param secondaryActions
   *        An optional JavaScript array describing the notification's alternate
   *        actions. The array should contain objects with the same properties
   *        as mainAction. These are used to populate the notification button's
   *        dropdown menu.
   * @param options
   *        An options JavaScript object holding additional properties for the
   *        notification. The following properties are currently supported:
   *        persistence: An integer. The notification will not automatically
   *                     dismiss for this many page loads.
   *        timeout:     A time in milliseconds. The notification will not
   *                     automatically dismiss before this time.
   *        persistWhileVisible:
   *                     A boolean. If true, a visible notification will always
   *                     persist across location changes.
   *        dismissed:   Whether the notification should be added as a dismissed
   *                     notification. Dismissed notifications can be activated
   *                     by clicking on their anchorElement.
   *        eventCallback:
   *                     Callback to be invoked when the notification changes
   *                     state. The callback's first argument is a string
   *                     identifying the state change:
   *                     "dismissed": notification has been dismissed by the
   *                                  user (e.g. by clicking away or switching
   *                                  tabs)
   *                     "removed": notification has been removed (due to
   *                                location change or user action)
   *                     "shown": notification has been shown (this can be fired
   *                              multiple times as notifications are dismissed
   *                              and re-shown)
   *        neverShow:   Indicate that no popup should be shown for this
   *                     notification. Useful for just showing the anchor icon.
   *        removeOnDismissal:
   *                     Notifications with this parameter set to true will be
   *                     removed when they would have otherwise been dismissed
   *                     (i.e. any time the popup is closed due to user
   *                     interaction).
   *        popupIconURL:
   *                     A string. URL of the image to be displayed in the popup.
   *                     Normally specified in CSS using list-style-image and the
   *                     .popup-notification-icon[popupid=...] selector.
   * @returns the Notification object corresponding to the added notification.
   */
  show: function PopupNotifications_show(browser, id, message, anchorID,
                                         mainAction, secondaryActions, options) {
    function isInvalidAction(a) {
      return !a || !(typeof(a.callback) == "function") || !a.label || !a.accessKey;
    }

    if (!browser)
      throw "PopupNotifications_show: invalid browser";
    if (!id)
      throw "PopupNotifications_show: invalid ID";
    if (mainAction && isInvalidAction(mainAction))
      throw "PopupNotifications_show: invalid mainAction";
    if (secondaryActions && secondaryActions.some(isInvalidAction))
      throw "PopupNotifications_show: invalid secondaryActions";

    let notification = new Notification(id, message, anchorID, mainAction,
                                        secondaryActions, browser, this, options);

    if (options && options.dismissed)
      notification.dismissed = true;

    let existingNotification = this.getNotification(id, browser);
    if (existingNotification)
      this._remove(existingNotification);

    let notifications = this._getNotificationsForBrowser(browser);
    notifications.push(notification);

    let fm = Cc["@mozilla.org/focus-manager;1"].getService(Ci.nsIFocusManager);
    if (browser.docShell.isActive && fm.activeWindow == this.window) {
      // show panel now
      this._update(notifications, notification.anchorElement, true);
    } else {
      // Otherwise, update() will display the notification the next time the
      // relevant tab/window is selected.

      // If the tab is selected but the window is in the background, let the OS
      // tell the user that there's a notification waiting in that window.
      // At some point we might want to do something about background tabs here
      // too. When the user switches to this window, we'll show the panel if
      // this browser is a tab (thus showing the anchor icon). For
      // non-tabbrowser browsers, we need to make the icon visible now or the
      // user will not be able to open the panel.
      if (!notification.dismissed && browser.docShell.isActive) {
        this.window.getAttention();
        if (notification.anchorElement.parentNode != this.iconBox) {
          notification.anchorElement.setAttribute(ICON_ATTRIBUTE_SHOWING, "true");
        }
      }

      // Notify observers that we're not showing the popup (useful for testing)
      this._notify("backgroundShow");
    }

    return notification;
  },

  /**
   * Returns true if the notification popup is currently being displayed.
   */
  get isPanelOpen() {
    let panelState = this.panel.state;

    return panelState == "showing" || panelState == "open";
  },

  /**
   * Called by the consumer to indicate that a browser's location has changed,
   * so that we can update the active notifications accordingly.
   */
  locationChange: function PopupNotifications_locationChange(aBrowser) {
    if (!aBrowser)
      throw "PopupNotifications_locationChange: invalid browser";

    let notifications = this._getNotificationsForBrowser(aBrowser);

    notifications = notifications.filter(function (notification) {
      // The persistWhileVisible option allows an open notification to persist
      // across location changes
      if (notification.options.persistWhileVisible &&
          this.isPanelOpen) {
        if ("persistence" in notification.options &&
          notification.options.persistence)
          notification.options.persistence--;
        return true;
      }

      // The persistence option allows a notification to persist across multiple
      // page loads
      if ("persistence" in notification.options &&
          notification.options.persistence) {
        notification.options.persistence--;
        return true;
      }

      // The timeout option allows a notification to persist until a certain time
      if ("timeout" in notification.options &&
          Date.now() <= notification.options.timeout) {
        return true;
      }

      this._fireCallback(notification, NOTIFICATION_EVENT_REMOVED);
      return false;
    }, this);

    this._setNotificationsForBrowser(aBrowser, notifications);

    if (aBrowser.docShell.isActive) {
      // get the anchor element if the browser has defined one so it will
      // _update will handle both the tabs iconBox and non-tab permission
      // anchors.
      let anchorElement = notifications.length > 0 ? notifications[0].anchorElement : null;
      if (!anchorElement)
        anchorElement = getAnchorFromBrowser(aBrowser);
      this._update(notifications, anchorElement);
    }
  },

  /**
   * Removes a Notification.
   * @param notification
   *        The Notification object to remove.
   */
  remove: function PopupNotifications_remove(notification) {
    this._remove(notification);
    
    if (notification.browser.docShell.isActive) {
      let notifications = this._getNotificationsForBrowser(notification.browser);
      this._update(notifications, notification.anchorElement);
    }
  },

  handleEvent: function (aEvent) {
    switch (aEvent.type) {
      case "popuphidden":
        this._onPopupHidden(aEvent);
        break;
      case "activate":
      case "TabSelect":
        let self = this;
        // setTimeout(..., 0) needed, otherwise openPopup from "activate" event
        // handler results in the popup being hidden again for some reason...
        this.window.setTimeout(function () {
          self._update();
        }, 0);
        break;
      case "click":
      case "keypress":
        this._onIconBoxCommand(aEvent);
        break;
    }
  },

////////////////////////////////////////////////////////////////////////////////
// Utility methods
////////////////////////////////////////////////////////////////////////////////

  _ignoreDismissal: null,
  _currentAnchorElement: null,

  /**
   * Gets notifications for the currently selected browser.
   */
  get _currentNotifications() {
    return this.tabbrowser.selectedBrowser ? this._getNotificationsForBrowser(this.tabbrowser.selectedBrowser) : [];
  },

  _remove: function PopupNotifications_removeHelper(notification) {
    // This notification may already be removed, in which case let's just fail
    // silently.
    let notifications = this._getNotificationsForBrowser(notification.browser);
    if (!notifications)
      return;

    var index = notifications.indexOf(notification);
    if (index == -1)
      return;

    if (notification.browser.docShell.isActive)
      notification.anchorElement.removeAttribute(ICON_ATTRIBUTE_SHOWING);

    // remove the notification
    notifications.splice(index, 1);
    this._fireCallback(notification, NOTIFICATION_EVENT_REMOVED);
  },

  /**
   * Dismisses the notification without removing it.
   */
  _dismiss: function PopupNotifications_dismiss() {
    let browser = this.panel.firstChild &&
                  this.panel.firstChild.notification.browser;
    this.panel.hidePopup();
    if (browser)
      browser.focus();
  },

  /**
   * Hides the notification popup.
   */
  _hidePanel: function PopupNotifications_hide() {
    this._ignoreDismissal = true;
    this.panel.hidePopup();
    this._ignoreDismissal = false;
  },

  /**
   * Removes all notifications from the notification popup.
   */
  _clearPanel: function () {
    let popupnotification;
    while ((popupnotification = this.panel.lastChild)) {
      this.panel.removeChild(popupnotification);

      // If this notification was provided by the chrome document rather than
      // created ad hoc, move it back to where we got it from.
      let originalParent = gNotificationParents.get(popupnotification);
      if (originalParent) {
        popupnotification.notification = null;

        // Remove nodes dynamically added to the notification's menu button
        // in _refreshPanel. Keep popupnotificationcontent nodes; they are
        // provided by the chrome document.
        let contentNode = popupnotification.lastChild;
        while (contentNode) {
          let previousSibling = contentNode.previousSibling;
          if (contentNode.nodeName != "popupnotificationcontent")
            popupnotification.removeChild(contentNode);
          contentNode = previousSibling;
        }

        // Re-hide the notification such that it isn't rendered in the chrome
        // document. _refreshPanel will unhide it again when needed.
        popupnotification.hidden = true;

        originalParent.appendChild(popupnotification);
      }
    }
  },

  _refreshPanel: function PopupNotifications_refreshPanel(notificationsToShow) {
    this._clearPanel();

    const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";

    notificationsToShow.forEach(function (n) {
      let doc = this.window.document;

      // Append "-notification" to the ID to try to avoid ID conflicts with other stuff
      // in the document.
      let popupnotificationID = n.id + "-notification";

      // If the chrome document provides a popupnotification with this id, use
      // that. Otherwise create it ad-hoc.
      let popupnotification = doc.getElementById(popupnotificationID);
      if (popupnotification)
        gNotificationParents.set(popupnotification, popupnotification.parentNode);
      else
        popupnotification = doc.createElementNS(XUL_NS, "popupnotification");

      popupnotification.setAttribute("label", n.message);
      popupnotification.setAttribute("id", popupnotificationID);
      popupnotification.setAttribute("popupid", n.id);
      popupnotification.setAttribute("closebuttoncommand", "PopupNotifications._dismiss();");
      if (n.mainAction) {
        popupnotification.setAttribute("buttonlabel", n.mainAction.label);
        popupnotification.setAttribute("buttonaccesskey", n.mainAction.accessKey);
        popupnotification.setAttribute("buttoncommand", "PopupNotifications._onButtonCommand(event);");
        popupnotification.setAttribute("menucommand", "PopupNotifications._onMenuCommand(event);");
        popupnotification.setAttribute("closeitemcommand", "PopupNotifications._dismiss();event.stopPropagation();");
      } else {
        popupnotification.removeAttribute("buttonlabel");
        popupnotification.removeAttribute("buttonaccesskey");
        popupnotification.removeAttribute("buttoncommand");
        popupnotification.removeAttribute("menucommand");
        popupnotification.removeAttribute("closeitemcommand");
      }

      if (n.options.popupIconURL)
        popupnotification.setAttribute("icon", n.options.popupIconURL);
      popupnotification.notification = n;

      if (n.secondaryActions) {
        n.secondaryActions.forEach(function (a) {
          let item = doc.createElementNS(XUL_NS, "menuitem");
          item.setAttribute("label", a.label);
          item.setAttribute("accesskey", a.accessKey);
          item.notification = n;
          item.action = a;

          popupnotification.appendChild(item);
        }, this);

        if (n.secondaryActions.length) {
          let closeItemSeparator = doc.createElementNS(XUL_NS, "menuseparator");
          popupnotification.appendChild(closeItemSeparator);
        }
      }

      this.panel.appendChild(popupnotification);

      // The popupnotification may be hidden if we got it from the chrome
      // document rather than creating it ad hoc.
      popupnotification.hidden = false;
    }, this);
  },

  _showPanel: function PopupNotifications_showPanel(notificationsToShow, anchorElement) {
    this.panel.hidden = false;

    notificationsToShow.forEach(function (n) {
      this._fireCallback(n, NOTIFICATION_EVENT_SHOWING);
    }, this);
    this._refreshPanel(notificationsToShow);

    if (this.isPanelOpen && this._currentAnchorElement == anchorElement)
      return;

    // If the panel is already open but we're changing anchors, we need to hide
    // it first.  Otherwise it can appear in the wrong spot.  (_hidePanel is
    // safe to call even if the panel is already hidden.)
    this._hidePanel();

    // If the anchor element is hidden or null, use the tab as the anchor. We
    // only ever show notifications for the current browser, so we can just use
    // the current tab.
    let selectedTab = this.tabbrowser.selectedTab;
    if (anchorElement) {
      let bo = anchorElement.boxObject;
      if (bo.height == 0 && bo.width == 0)
        anchorElement = selectedTab; // hidden
    } else {
      anchorElement = selectedTab; // null
    }

    this._currentAnchorElement = anchorElement;

    // On OS X and Linux we need a different panel arrow color for
    // click-to-play plugins, so copy the popupid and use css.
    this.panel.setAttribute("popupid", this.panel.firstChild.getAttribute("popupid"));
    notificationsToShow.forEach(function (n) {
      // Remember the time the notification was shown for the security delay.
      n.timeShown = this.window.performance.now();
    }, this);
    this.panel.openPopup(anchorElement, "bottomcenter topleft");
    notificationsToShow.forEach(function (n) {
      this._fireCallback(n, NOTIFICATION_EVENT_SHOWN);
    }, this);
  },

  /**
   * Updates the notification state in response to window activation or tab
   * selection changes.
   *
   * @param notifications an array of Notification instances. if null,
   *                      notifications will be retrieved off the current
   *                      browser tab
   * @param anchor is a XUL element that the notifications panel will be
   *                      anchored to
   * @param dismissShowing if true, dismiss any currently visible notifications
   *                       if there are no notifications to show. Otherwise,
   *                       currently displayed notifications will be left alone.
   */
  _update: function PopupNotifications_update(notifications, anchor, dismissShowing = false) {
    let useIconBox = this.iconBox && (!anchor || anchor.parentNode == this.iconBox);
    if (useIconBox) {
      // hide icons of the previous tab.
      this._hideIcons();
    }

    let anchorElement = anchor, notificationsToShow = [];
    if (!notifications)
      notifications = this._currentNotifications;
    let haveNotifications = notifications.length > 0;
    if (haveNotifications) {
      // Only show the notifications that have the passed-in anchor (or the
      // first notification's anchor, if none was passed in). Other
      // notifications will be shown once these are dismissed.
      anchorElement = anchor || notifications[0].anchorElement;

      if (useIconBox) {
        this._showIcons(notifications);
        this.iconBox.hidden = false;
      } else if (anchorElement) {
        anchorElement.setAttribute(ICON_ATTRIBUTE_SHOWING, "true");
        // use the anchorID as a class along with the default icon class as a
        // fallback if anchorID is not defined in CSS. We always use the first
        // notifications icon, so in the case of multiple notifications we'll
        // only use the default icon
        if (anchorElement.classList.contains("notification-anchor-icon")) {
          // remove previous icon classes
          let className = anchorElement.className.replace(/([-\w]+-notification-icon\s?)/g,"")
          className = "default-notification-icon " + className;
          if (notifications.length == 1) {
            className = notifications[0].anchorID + " " + className;
          }
          anchorElement.className = className;
        }
      }

      // Also filter out notifications that have been dismissed.
      notificationsToShow = notifications.filter(function (n) {
        return !n.dismissed && n.anchorElement == anchorElement &&
               !n.options.neverShow;
      });
    }

    if (notificationsToShow.length > 0) {
      this._showPanel(notificationsToShow, anchorElement);
    } else {
      // Notify observers that we're not showing the popup (useful for testing)
      this._notify("updateNotShowing");

      // Close the panel if there are no notifications to show.
      // When called from PopupNotifications.show() we should never close the
      // panel, however. It may just be adding a dismissed notification, in
      // which case we want to continue showing any existing notifications.
      if (!dismissShowing)
        this._dismiss();

      // Only hide the iconBox if we actually have no notifications (as opposed
      // to not having any showable notifications)
      if (!haveNotifications) {
        if (useIconBox)
          this.iconBox.hidden = true;
        else if (anchorElement)
          anchorElement.removeAttribute(ICON_ATTRIBUTE_SHOWING);
      }
    }
  },

  _showIcons: function PopupNotifications_showIcons(aCurrentNotifications) {
    for (let notification of aCurrentNotifications) {
      let anchorElm = notification.anchorElement;
      if (anchorElm) {
        anchorElm.setAttribute(ICON_ATTRIBUTE_SHOWING, "true");
      }
    }
  },

  _hideIcons: function PopupNotifications_hideIcons() {
    let icons = this.iconBox.querySelectorAll(ICON_SELECTOR);
    for (let icon of icons) {
      icon.removeAttribute(ICON_ATTRIBUTE_SHOWING);
    }
  },

  /**
   * Gets and sets notifications for the browser.
   */
  _getNotificationsForBrowser: function PopupNotifications_getNotifications(browser) {
    let notifications = popupNotificationsMap.get(browser);
    if (!notifications) {
      // Initialize the WeakMap for the browser so callers can reference/manipulate the array.
      notifications = [];
      popupNotificationsMap.set(browser, notifications);
    }
    return notifications;
  },
  _setNotificationsForBrowser: function PopupNotifications_setNotifications(browser, notifications) {
    popupNotificationsMap.set(browser, notifications);
    return notifications;
  },

  _onIconBoxCommand: function PopupNotifications_onIconBoxCommand(event) {
    // Left click, space or enter only
    let type = event.type;
    if (type == "click" && event.button != 0)
      return;

    if (type == "keypress" &&
        !(event.charCode == Ci.nsIDOMKeyEvent.DOM_VK_SPACE ||
          event.keyCode == Ci.nsIDOMKeyEvent.DOM_VK_RETURN))
      return;

    if (this._currentNotifications.length == 0)
      return;

    // Get the anchor that is the immediate child of the icon box
    let anchor = event.target;
    while (anchor && anchor.parentNode != this.iconBox)
      anchor = anchor.parentNode;

    this._reshowNotifications(anchor);
  },

  _reshowNotifications: function PopupNotifications_reshowNotifications(anchor, browser) {
    // Mark notifications anchored to this anchor as un-dismissed
    let notifications = this._getNotificationsForBrowser(browser || this.tabbrowser.selectedBrowser);
    notifications.forEach(function (n) {
      if (n.anchorElement == anchor)
        n.dismissed = false;
    });

    // ...and then show them.
    this._update(notifications, anchor);
  },

  _fireCallback: function PopupNotifications_fireCallback(n, event) {
    if (n.options.eventCallback)
      n.options.eventCallback.call(n, event);
  },

  _onPopupHidden: function PopupNotifications_onPopupHidden(event) {
    if (event.target != this.panel || this._ignoreDismissal)
      return;

    let browser = this.panel.firstChild &&
                  this.panel.firstChild.notification.browser;
    if (!browser)
      return;

    let notifications = this._getNotificationsForBrowser(browser);
    // Mark notifications as dismissed and call dismissal callbacks
    Array.forEach(this.panel.childNodes, function (nEl) {
      let notificationObj = nEl.notification;
      // Never call a dismissal handler on a notification that's been removed.
      if (notifications.indexOf(notificationObj) == -1)
        return;

      // Do not mark the notification as dismissed or fire NOTIFICATION_EVENT_DISMISSED
      // if the notification is removed.
      if (notificationObj.options.removeOnDismissal)
        this._remove(notificationObj);
      else {
        notificationObj.dismissed = true;
        this._fireCallback(notificationObj, NOTIFICATION_EVENT_DISMISSED);
      }
    }, this);

    this._clearPanel();

    this._update();
  },

  _onButtonCommand: function PopupNotifications_onButtonCommand(event) {
    // Need to find the associated notification object, which is a bit tricky
    // since it isn't associated with the button directly - this is kind of
    // gross and very dependent on the structure of the popupnotification
    // binding's content.
    let target = event.originalTarget;
    let notificationEl;
    let parent = target;
    while (parent && (parent = target.ownerDocument.getBindingParent(parent)))
      notificationEl = parent;

    if (!notificationEl)
      throw "PopupNotifications_onButtonCommand: couldn't find notification element";

    if (!notificationEl.notification)
      throw "PopupNotifications_onButtonCommand: couldn't find notification";

    let notification = notificationEl.notification;
    let timeSinceShown = this.window.performance.now() - notification.timeShown;

    // Only report the first time mainAction is triggered and remember that this occurred.
    if (!notification.timeMainActionFirstTriggered) {
      notification.timeMainActionFirstTriggered = timeSinceShown;
      Services.telemetry.getHistogramById("POPUP_NOTIFICATION_MAINACTION_TRIGGERED_MS").
                         add(timeSinceShown);
    }

    if (timeSinceShown < this.buttonDelay) {
      Services.console.logStringMessage("PopupNotifications_onButtonCommand: " +
                                        "Button click happened before the security delay: " +
                                        timeSinceShown + "ms");
      return;
    }
    notification.mainAction.callback.call();

    this._remove(notification);
    this._update();
  },

  _onMenuCommand: function PopupNotifications_onMenuCommand(event) {
    let target = event.originalTarget;
    if (!target.action || !target.notification)
      throw "menucommand target has no associated action/notification";

    event.stopPropagation();
    target.action.callback.call();

    this._remove(target.notification);
    this._update();
  },

  _notify: function PopupNotifications_notify(topic) {
    Services.obs.notifyObservers(null, "PopupNotifications-" + topic, "");
  },
};