/* -*- Mode: javascript; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 ; js-indent-level: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/*
 * 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/. */

Components.utils.import("resource://gre/modules/Services.jsm");
// Ensure the activity modules are loaded for this window.
Components.utils.import("resource:///modules/activity/activityModules.js");
Components.utils.import("resource:///modules/mailServices.js");

const nsIAbListener = Components.interfaces.nsIAbListener;
const kPrefMailAddrBookLastNameFirst = "mail.addr_book.lastnamefirst";
const kPersistCollapseMapStorage = "directoryTree.json";

var gSearchTimer = null;
var gStatusText = null;
var gQueryURIFormat = null;
var gCardViewBox;
var gCardViewBoxEmail1;
var gPreviousDirTreeIndex = -1;

var msgWindow = Components.classes["@mozilla.org/messenger/msgwindow;1"]
                          .createInstance(Components.interfaces.nsIMsgWindow);

let chatHandler = {};
Components.utils.import("resource:///modules/chatHandler.jsm", chatHandler);

// Constants that correspond to choices
// in Address Book->View -->Show Name as
const kDisplayName = 0;
const kLastNameFirst = 1;
const kFirstNameFirst = 2;
const kLDAPDirectory = 0; // defined in nsDirPrefs.h
const kPABDirectory  = 2; // defined in nsDirPrefs.h

// These chat properties are the ones that our IM component supports. If a
// contact has a value for one of these properties, we can communicate with
// that contact (assuming that the user has added that value to their list
// of IM contacts).
const kChatProperties = ["_GoogleTalk", "_JabberId"];

// Note: We need to keep this listener as it does not just handle dir
// pane deletes but also deletes of address books and lists from places like
// the sidebar and LDAP preference pane.
var gAddressBookAbListener = {
  onItemAdded: function(parentDir, item) {
    // will not be called
  },
  onItemRemoved: function(parentDir, item) {
    // will only be called when an addressbook is deleted
    try {
      // If we don't have a record of the previous selection, the only
      // option is to select the first.
      if (gPreviousDirTreeIndex == -1) {
        SelectFirstAddressBook();
      }
      else {
        // Don't reselect if we already have a valid selection, this may be
        // the case if items are being removed via other methods, e.g. sidebar,
        // LDAP preference pane etc.
        if (gDirTree.currentIndex == -1) {
          var directory = item.QueryInterface(Components.interfaces.nsIAbDirectory);

          // If we are a mail list, move the selection up the list before
          // trying to find the parent. This way we'll end up selecting the
          // parent address book when we remove a mailing list.
          //
          // For simple address books we don't need to move up the list, as
          // we want to select the next one upon removal.
          if (directory.isMailList && gPreviousDirTreeIndex > 0)
            --gPreviousDirTreeIndex;

          // Now get the parent of the row.
          var newRow = gDirTree.view.getParentIndex(gPreviousDirTreeIndex);

          // if we have no parent (i.e. we are an address book), use the
          // previous index.
          if (newRow == -1)
            newRow = gPreviousDirTreeIndex;

          // Fall back to the first adddress book if we're not in a valid range
          if (newRow >= gDirTree.view.rowCount)
            newRow = 0;

          // Now select the new item.
          gDirTree.view.selection.select(newRow);
        }
      }
    }
    catch (ex) {
    }
  },
  onItemPropertyChanged: function(item, property, oldValue, newValue) {
    // will not be called
  }
};

function OnUnloadAddressBook()
{
  MailServices.ab.removeAddressBookListener(gAddressBookAbListener);
  MailServices.ab.removeAddressBookListener(gDirectoryTreeView);

  // Shutdown the tree view - this will also save the open/collapsed
  // state of the tree view to a JSON file.
  gDirectoryTreeView.shutdown(kPersistCollapseMapStorage);

  MailServices.mailSession.RemoveMsgWindow(msgWindow);

  ToolbarIconColor.uninit();

  CloseAbView();
}

var gAddressBookAbViewListener = {
  onSelectionChanged: function() {
    ResultsPaneSelectionChanged();
  },
  onCountChanged: function(total) {
    SetStatusText(total);
  }
};

function GetAbViewListener()
{
  return gAddressBookAbViewListener;
}

// we won't show the window until the onload() handler is finished
// so we do this trick (suggested by hyatt / blaker)
function OnLoadAddressBook()
{
  // Set a sane starting width/height for all resolutions on new profiles.
  // Do this before the window loads.
  if (!document.documentElement.hasAttribute("width"))
  {
    // Prefer 860xfull height.
    let defaultHeight = screen.availHeight;
    let defaultWidth = (screen.availWidth >= 860) ? 860 : screen.availWidth;

    // On small screens, default to maximized state.
    if (defaultHeight <= 600)
      document.documentElement.setAttribute("sizemode", "maximized");

    document.documentElement.setAttribute("width", defaultWidth);
    document.documentElement.setAttribute("height", defaultHeight);
    // Make sure we're safe at the left/top edge of screen
    document.documentElement.setAttribute("screenX", screen.availLeft);
    document.documentElement.setAttribute("screenY", screen.availTop);
  }

  ToolbarIconColor.init();

  if (!chatHandler.ChatCore.initialized)
    chatHandler.ChatCore.init();

  setTimeout(delayedOnLoadAddressBook, 0); // when debugging, set this to 5000, so you can see what happens after the window comes up.
}

function delayedOnLoadAddressBook()
{
  verifyAccounts(null, false);   // this will do migration, if we need to.

  InitCommonJS();

  GetCurrentPrefs();

  // FIX ME - later we will be able to use onload from the overlay
  OnLoadCardView();

  // Initialize the Address Book tree view
  gDirectoryTreeView.init(gDirTree,
                          kPersistCollapseMapStorage);

  SelectFirstAddressBook();

  // if the pref is locked disable the menuitem New->LDAP directory
  if (Services.prefs.prefIsLocked("ldap_2.disable_button_add"))
    document.getElementById("addLDAP").setAttribute("disabled", "true");

  // Add a listener, so we can switch directories if the current directory is
  // deleted. This listener cares when a directory (= address book), or a
  // directory item is/are removed. In the case of directory items, we are
  // only really interested in mailing list changes and not cards but we have
  // to have both.
  MailServices.ab.addAddressBookListener(gAddressBookAbListener,
                                   nsIAbListener.directoryRemoved |
                                   nsIAbListener.directoryItemRemoved);
  MailServices.ab.addAddressBookListener(gDirectoryTreeView, nsIAbListener.all);


  gDirTree.controllers.appendController(DirPaneController);
  gAbResultsTree.controllers.appendController(abResultsController);
  // Force command update for the benefit of DirPaneController and
  // abResultsController
  CommandUpdate_AddressBook();

  // initialize the customizeDone method on the customizeable toolbar
  var toolbox = document.getElementById("ab-toolbox");
  toolbox.customizeDone = function(aEvent) { MailToolboxCustomizeDone(aEvent, "CustomizeABToolbar"); };

  var toolbarset = document.getElementById('customToolbars');
  toolbox.toolbarset = toolbarset;

  // Ensure we don't load xul error pages into the main window
  window.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
        .getInterface(Components.interfaces.nsIWebNavigation)
        .QueryInterface(Components.interfaces.nsIDocShell)
        .useErrorPages = false;

  MailServices.mailSession.AddMsgWindow(msgWindow);

  // Focus the searchbox as we think the user will want to do that
  // with the highest probability.
  // Bug 1143812: This is disabled for now to keep the New Contact command enabled.
  // QuickSearchFocus();
}


function GetCurrentPrefs()
{
  // check "Show Name As" menu item based on pref
  var menuitemID;
  switch (Services.prefs.getIntPref(kPrefMailAddrBookLastNameFirst))
  {
    case kFirstNameFirst:
      menuitemID = 'firstLastCmd';
      break;
    case kLastNameFirst:
      menuitemID = 'lastFirstCmd';
      break;
    case kDisplayName:
    default:
      menuitemID = 'displayNameCmd';
      break;
  }

  var menuitem = top.document.getElementById(menuitemID);
  if (menuitem)
    menuitem.setAttribute('checked', 'true');

  // initialize phonetic
  var showPhoneticFields =
    Services.prefs.getComplexValue("mail.addr_book.show_phonetic_fields",
      Components.interfaces.nsIPrefLocalizedString).data;
  // show phonetic fields if indicated by the pref
  if (showPhoneticFields == "true")
    document.getElementById("cmd_SortBy_PhoneticName")
            .setAttribute("hidden", "false");

}

function SetNameColumn(cmd)
{
  var prefValue;

  switch ( cmd )
  {
    case 'firstLastCmd':
      prefValue = kFirstNameFirst;
      break;
    case 'lastFirstCmd':
      prefValue = kLastNameFirst;
      break;
    case 'displayNameCmd':
      prefValue = kDisplayName;
      break;
  }

  Services.prefs.setIntPref(kPrefMailAddrBookLastNameFirst, prefValue);
}

function onOSXFileMenuInit()
{
  document.getElementById('menu_osxAddressBook')
          .setAttribute("checked", AbOSXAddressBookExists());
}

function CommandUpdate_AddressBook()
{
  goUpdateCommand('cmd_delete');
  goUpdateCommand('button_delete');
  goUpdateCommand('cmd_properties');
  goUpdateCommand('cmd_newlist');
  goUpdateCommand('cmd_newCard');
  goUpdateCommand('cmd_chatWithCard');
}

function ResultsPaneSelectionChanged()
{
  UpdateCardView();
}

function UpdateCardView()
{
  var cards = GetSelectedAbCards();

  if (!cards) {
    ClearCardViewPane();
    return;
  }

  // display the selected card, if exactly one card is selected.
  // either no cards, or more than one card is selected, clear the pane.
  // We do not need to check cards[0] any more since GetSelectedAbCards() only
  // push non-null entity to the list.
  if (cards.length == 1)
    OnClickedCard(cards[0])
  else
    ClearCardViewPane();
}

function OnClickedCard(card)
{
  if (card)
    DisplayCardViewPane(card);
  else
    ClearCardViewPane();
}

function AbClose()
{
  top.close();
}

function AbPrintCardInternal(doPrintPreview, msgType)
{
  var selectedItems = GetSelectedAbCards();
  var numSelected = selectedItems.length;

  if (!numSelected)
    return;

  var uri = GetSelectedDirectory();
  if (!uri)
    return;

   var statusFeedback;
   statusFeedback = Components.classes["@mozilla.org/messenger/statusfeedback;1"].createInstance();
   statusFeedback = statusFeedback.QueryInterface(Components.interfaces.nsIMsgStatusFeedback);

   var selectionArray = new Array(numSelected);

   var totalCard = 0;

   for (var i = 0; i < numSelected; i++)
   {
     var card = selectedItems[i];
     var printCardUrl = CreatePrintCardUrl(card);
     if (printCardUrl)
     {
        selectionArray[totalCard++] = printCardUrl;
     }
  }

  printEngineWindow = window.openDialog("chrome://messenger/content/msgPrintEngine.xul",
                                         "",
                                         "chrome,dialog=no,all",
                                          totalCard, selectionArray, statusFeedback,
                                          doPrintPreview, msgType);

  return;
}

function AbPrintCard()
{
  AbPrintCardInternal(false, Components.interfaces.nsIMsgPrintEngine.MNAB_PRINT_AB_CARD);
}

function AbPrintPreviewCard()
{
  AbPrintCardInternal(true, Components.interfaces.nsIMsgPrintEngine.MNAB_PRINTPREVIEW_AB_CARD);
}

function CreatePrintCardUrl(card)
{
  return "data:application/xml;base64," + card.translateTo("base64xml");
}

function AbPrintAddressBookInternal(doPrintPreview, msgType)
{
  var uri = GetSelectedDirectory();
  if (!uri)
    return;

  var statusFeedback;
  statusFeedback = Components.classes["@mozilla.org/messenger/statusfeedback;1"].createInstance();
  statusFeedback = statusFeedback.QueryInterface(Components.interfaces.nsIMsgStatusFeedback);

  /*
    turn "moz-abmdbdirectory://abook.mab" into
    "addbook://moz-abmdbdirectory/abook.mab?action=print"
   */

  var abURIArr = uri.split("://");
  var printUrl = "addbook://" + abURIArr[0] + "/" + abURIArr[1] + "?action=print"

  printEngineWindow = window.openDialog("chrome://messenger/content/msgPrintEngine.xul",
                    "",
                    "chrome,dialog=no,all",
                    1, [printUrl], statusFeedback, doPrintPreview, msgType);

  return;
}

function AbPrintAddressBook()
{
  AbPrintAddressBookInternal(false, Components.interfaces.nsIMsgPrintEngine.MNAB_PRINT_ADDRBOOK);
}

function AbPrintPreviewAddressBook()
{
  AbPrintAddressBookInternal(true, Components.interfaces.nsIMsgPrintEngine.MNAB_PRINTPREVIEW_ADDRBOOK);
}

function AbExport()
{
  try {
    let selectedABURI = GetSelectedDirectory();
    if (!selectedABURI) return;

    let directory = GetDirectoryFromURI(selectedABURI);
    MailServices.ab.exportAddressBook(window, directory);
  }
  catch (ex) {
    let message;
    switch (ex.result) {
      case Components.results.NS_ERROR_FILE_ACCESS_DENIED:
        message = gAddressBookBundle.getString("failedToExportMessageFileAccessDenied");
        break;
      case Components.results.NS_ERROR_FILE_NO_DEVICE_SPACE:
        message = gAddressBookBundle.getString("failedToExportMessageNoDeviceSpace");
        break;
      default:
        message = ex.message;
        break;
    }

    Services.prompt.alert(window,
      gAddressBookBundle.getString("failedToExportTitle"),
      message);
  }
}

function SetStatusText(total)
{
  if (!gStatusText)
    gStatusText = document.getElementById('statusText');

  try {
    var statusText;

    var searchInput = document.getElementById("peopleSearchInput");
    if (searchInput && searchInput.value) {
      if (total == 0)
        statusText = gAddressBookBundle.getString("noMatchFound");
      else
      {
        if (total == 1)
          statusText = gAddressBookBundle.getString("matchFound");
        else
          statusText = gAddressBookBundle.getFormattedString("matchesFound", [total]);
      }
    }
    else
      statusText =
        gAddressBookBundle.getFormattedString(
          "totalContactStatus",
          [GetDirectoryFromURI(GetSelectedDirectory()).dirName, total]);

    gStatusText.setAttribute("label", statusText);
  }
  catch(ex) {
    Components.utils.reportError("ERROR: failed to set status text:  " + ex );
  }
}

function AbResultsPaneKeyPress(event)
{
  if (event.keyCode == 13)
    AbEditSelectedCard();
}

function AbResultsPaneDoubleClick(card)
{
  AbEditCard(card);
}

function onAdvancedAbSearch()
{
  var selectedABURI = GetSelectedDirectory();
  if (!selectedABURI) return;

  let existingSearchWindow = Services.wm.getMostRecentWindow("mailnews:absearch");
  if (existingSearchWindow)
    existingSearchWindow.focus();
  else
    window.openDialog("chrome://messenger/content/ABSearchDialog.xul", "",
                      "chrome,resizable,status,centerscreen,dialog=no",
                      {directory: selectedABURI});
}

function onEnterInSearchBar()
{
  ClearCardViewPane();
  if (!gQueryURIFormat) {
    gQueryURIFormat = Services.prefs
      .getComplexValue("mail.addr_book.quicksearchquery.format",
                       Components.interfaces.nsIPrefLocalizedString).data;

    // Remove the preceeding '?' as we have to prefix "?and" to this format.
    gQueryURIFormat = gQueryURIFormat.slice(1);
  }

  var searchURI = GetSelectedDirectory();
  if (!searchURI) return;

  /*
   XXX todo, handle the case where the LDAP url
   already has a query, like
   moz-abldapdirectory://nsdirectory.netscape.com:389/ou=People,dc=netscape,dc=com?(or(Department,=,Applications))
  */
  var searchInput = document.getElementById("peopleSearchInput");
  // Use helper method to split up search query to multi-word search
  // query against multiple fields.
  if (searchInput) {
    let searchWords = getSearchTokens(searchInput.value);
    searchURI += generateQueryURI(gQueryURIFormat, searchWords);
  }

  if (searchURI == kAllDirectoryRoot)
    searchURI += "?";

  document.getElementById("localResultsOnlyMessage")
            .setAttribute("hidden",
                          !gDirectoryTreeView.hasRemoteAB ||
                          searchURI != kAllDirectoryRoot + "?");

  SetAbView(searchURI);

  // XXX todo
  // this works for synchronous searches of local addressbooks,
  // but not for LDAP searches
  SelectFirstCard();
}

function SwitchPaneFocus(event)
{
  var focusedElement    = WhichPaneHasFocus();
  var cardViewBox       = GetCardViewBox();
  var cardViewBoxEmail1 = GetCardViewBoxEmail1();
  var searchBox         = document.getElementById('search-container');
  var dirTree           = GetDirTree();
  var searchInput       = document.getElementById('peopleSearchInput');

  if (event && event.shiftKey)
  {
    if (focusedElement == gAbResultsTree && searchBox)
      searchInput.focus();
    else if ((focusedElement == gAbResultsTree || focusedElement == searchBox) && !IsDirPaneCollapsed())
      dirTree.focus();
    else if (focusedElement != cardViewBox && !IsCardViewAndAbResultsPaneSplitterCollapsed())
    {
      if (cardViewBoxEmail1)
        cardViewBoxEmail1.focus();
      else
        cardViewBox.focus();
    }
    else
      gAbResultsTree.focus();
  }
  else
  {
    if (focusedElement == searchBox)
      gAbResultsTree.focus();
    else if (focusedElement == gAbResultsTree && !IsCardViewAndAbResultsPaneSplitterCollapsed())
    {
      if (cardViewBoxEmail1)
        cardViewBoxEmail1.focus();
      else
        cardViewBox.focus();
    }
    else if (focusedElement != dirTree && !IsDirPaneCollapsed())
      dirTree.focus();
    else if (searchBox && searchInput)
      searchInput.focus();
    else
      gAbResultsTree.focus();
  }
}

function WhichPaneHasFocus()
{
  var cardViewBox       = GetCardViewBox();
  var searchBox         = document.getElementById('search-container');
  var dirTree           = GetDirTree();

  var currentNode = top.document.commandDispatcher.focusedElement;
  while (currentNode)
  {
    var nodeId = currentNode.getAttribute('id');

    if (currentNode == gAbResultsTree ||
        currentNode == cardViewBox ||
        currentNode == searchBox ||
        currentNode == dirTree)
      return currentNode;

    currentNode = currentNode.parentNode;
  }

  return null;
}

function GetDirTree()
{
  if (!gDirTree)
    gDirTree = document.getElementById('dirTree');
  return gDirTree;
}

function GetCardViewBox()
{
  if (!gCardViewBox)
    gCardViewBox = document.getElementById('CardViewBox');
  return gCardViewBox;
}

function GetCardViewBoxEmail1()
{
  if (!gCardViewBoxEmail1)
  {
    try {
      gCardViewBoxEmail1 = document.getElementById('cvEmail1');
    }
    catch (ex) {
      gCardViewBoxEmail1 = null;
    }
  }
  return gCardViewBoxEmail1;
}

function IsDirPaneCollapsed()
{
  var dirPaneBox = GetDirTree().parentNode;
  return dirPaneBox.getAttribute("collapsed") == "true" ||
         dirPaneBox.getAttribute("hidden") == "true";
}

function IsCardViewAndAbResultsPaneSplitterCollapsed()
{
  var cardViewBox = document.getElementById('CardViewOuterBox');
  try {
    return (cardViewBox.getAttribute("collapsed") == "true");
  }
  catch (ex) {
    return false;
  }
}

function LaunchUrl(url)
{
  // Doesn't matter if this bit fails, window.location contains its own prompts
  try {
    window.location = url;
  }
  catch (ex) {}
}

function AbIMSelected()
{
  let cards = GetSelectedAbCards();

  if (!cards) {
    Components.utils.reportError("ERROR: AbIMSelected: |cards| is null.");
    return;
  }

  if (cards.length != 1) {
    Components.utils.reportError("AbIMSelected should only be called when 1" +
                                 " card is selected. There are " +
                                 cards.length + " cards selected.");
    return;
  }

  let card = cards[0];

  if (!card) {
    Components.utils.reportError("AbIMSelected: one card was selected, but its only member was null.");
    return;
  }
  // We want to open a conversation with the first online username that we can
  // find. Failing that, we'll take the first offline (but still chat-able)
  // username we can find.
  //
  // First, sort the IM usernames into two groups - online contacts go into
  // the "online" group, and offline (but chat-able) contacts go into the
  // "offline" group.

  let online = [];
  let offline = [];

  for each (let [, chatProperty] in Iterator(kChatProperties)) {
    let chatID = card.getProperty(chatProperty, "");

    if (chatID && (chatID in chatHandler.allContacts)) {
      let chatContact = chatHandler.allContacts[chatID];
      if (chatContact.online)
        online.push(chatContact);
      else if (chatContact.canSendMessage)
        offline.push(chatContact);
    }
  }

  let selectedContact;

  // If we have any contacts in the online group, we'll take the first one.
  if (online.length)
    selectedContact = online[0];
  // If not, we'll take the first contact in the offline group.
  else if (offline.length)
    selectedContact = offline[0];

  // If we found a contact we can chat with, open / focus the chat tab with
  // a conversation opened with that contact.
  if (selectedContact) {
    let prplConv = selectedContact.createConversation();
    let uiConv = Services.conversations.getUIConversation(prplConv);
    let win = Services.wm.getMostRecentWindow("mail:3pane");

    if (win) {
      win.focus();
      win.showChatTab();
      win.chatHandler.focusConversation(uiConv);
    }
    else {
      window.openDialog("chrome://messenger/content/", "_blank",
                        "chrome,extrachrome,menubar,resizable,scrollbars,status,toolbar",
                        null, {tabType: "chat",
                               tabParams: {convType: "focus", conv: uiConv}});
    }

    return;
  }

  // Ok, if we get here, we're going the old route of trying to use AIM.
  let AIM = card.getProperty("_AimScreenName", "");
  if (AIM) {
    LaunchUrl("aim:goim?screenname=" + AIM);
    return;
  }

  // And if we got here, that means we couldn't find *any* usernames we could
  // chat with. That really shouldn't be possible, since the isEnabled for
  // cmd_chatWithCard makes checks for this sort of thing, but we'll throw
  // an exception for good measure.
  throw new Error("Couldn't find any usernames to chat with for this card.");
}

function getMailToolbox()
{
  return document.getElementById("ab-toolbox");
}

const kOSXDirectoryURI = "moz-abosxdirectory:///";
const kOSXPrefBase = "ldap_2.servers.osx";

function AbOSXAddressBookExists()
{
  // I hate doing it this way - until we redo how we manage address books
  // I can't think of a better way though.

  // See if the pref exists, if so, then we need to delete the address book
  var uriPresent = false;
  var position = 1;
  try {
    uriPresent = Services.prefs.getCharPref(kOSXPrefBase + ".uri") == kOSXDirectoryURI;
  }
  catch (e) { }

  try {
    position = Services.prefs.getIntPref(kOSXPrefBase + ".position");
  }
  catch (e) { }

  // Address book exists if the uri is correct and the position is not zero.
  return uriPresent && position != 0;
}

function AbShowHideOSXAddressBook()
{
  if (AbOSXAddressBookExists())
    MailServices.ab.deleteAddressBook(kOSXDirectoryURI);
  else {
    MailServices.ab.newAddressBook(
      gAddressBookBundle.getString(kOSXPrefBase + ".description"),
      kOSXDirectoryURI, 3, kOSXPrefBase);
  }
}

let abResultsController = {
  commands: {
    cmd_chatWithCard: {
      isEnabled: function() {
        let selected = GetSelectedAbCards();

        if (selected.length != 1)
          return false;

        let selectedCard = selected[0];
        if (!selectedCard)
          return false;

        let isIMContact = kChatProperties.some(function(aProperty) {
          let contactName = selectedCard.getProperty(aProperty, "");

          if (!contactName)
            return false;

          return (contactName in chatHandler.allContacts
                  && chatHandler.allContacts[contactName].canSendMessage);
        });

        let hasAIM = selectedCard.getProperty("_AimScreenName", "");

        return isIMContact || hasAIM;
      },

      doCommand: function() {
        AbIMSelected();
      },
    }
  },

  supportsCommand: function(aCommand) {
    return (aCommand in this.commands);
  },

  isCommandEnabled: function(aCommand) {
    if (!this.supportsCommand(aCommand))
      return false;

    return this.commands[aCommand].isEnabled();
  },

  doCommand: function(aCommand) {
    if (!this.supportsCommand(aCommand))
      return;
    let cmd = this.commands[aCommand];
    if (!cmd.isEnabled())
      return;
    cmd.doCommand();
  },

  onEvent: function(aEvent) {}
}
