/**
   * Utility method throwing an exception if the stack is not properly initialized.
   *
   * @throws java.lang.IllegalStateException if the underlying stack is not registered and
   *     initialized.
   */
  private void assertConnected() throws IllegalStateException {
    if (jabberProvider == null)
      throw new IllegalStateException(
          "The provider must be non-null and signed on the "
              + "service before being able to send a file.");
    else if (!jabberProvider.isRegistered()) {
      // if we are not registered but the current status is online
      // change the current status
      if (opSetPersPresence.getPresenceStatus().isOnline()) {
        opSetPersPresence.fireProviderStatusChangeEvent(
            opSetPersPresence.getPresenceStatus(),
            jabberProvider.getJabberStatusEnum().getStatus(JabberStatusEnum.OFFLINE));
      }

      throw new IllegalStateException(
          "The provider must be signed on the service before " + "being able to send a file.");
    }
  }
  /**
   * Subscribes this provider as interested in receiving notifications for new mail messages from
   * Google mail services such as Gmail or Google Apps.
   */
  private void subscribeForGmailNotifications() {
    // first check support for the notification service
    String accountIDService = jabberProvider.getAccountID().getService();
    boolean notificationsAreSupported =
        jabberProvider.isFeatureSupported(accountIDService, NewMailNotificationIQ.NAMESPACE);

    if (!notificationsAreSupported) {
      if (logger.isDebugEnabled())
        logger.debug(
            accountIDService
                + " does not seem to provide a Gmail notification "
                + " service so we won't be trying to subscribe for it");
      return;
    }

    if (logger.isDebugEnabled())
      logger.debug(
          accountIDService
              + " seems to provide a Gmail notification "
              + " service so we will try to subscribe for it");

    ProviderManager providerManager = ProviderManager.getInstance();

    providerManager.addIQProvider(
        MailboxIQ.ELEMENT_NAME, MailboxIQ.NAMESPACE, new MailboxIQProvider());
    providerManager.addIQProvider(
        NewMailNotificationIQ.ELEMENT_NAME,
        NewMailNotificationIQ.NAMESPACE,
        new NewMailNotificationProvider());

    Connection connection = jabberProvider.getConnection();

    connection.addPacketListener(new MailboxIQListener(), new PacketTypeFilter(MailboxIQ.class));
    connection.addPacketListener(
        new NewMailNotificationListener(), new PacketTypeFilter(NewMailNotificationIQ.class));

    if (opSetPersPresence.getCurrentStatusMessage().equals(JabberStatusEnum.OFFLINE)) return;

    // create a query with -1 values for newer-than-tid and
    // newer-than-time attributes
    MailboxQueryIQ mailboxQuery = new MailboxQueryIQ();

    if (logger.isTraceEnabled())
      logger.trace(
          "sending mailNotification for acc: "
              + jabberProvider.getAccountID().getAccountUniqueID());
    jabberProvider.getConnection().sendPacket(mailboxQuery);
  }
  /**
   * Sends a file transfer request to the given <tt>toContact</tt>.
   *
   * @return the transfer object
   * @param toContact the contact that should receive the file
   * @param file file to send
   * @param gw special gateway to be used for receiver if its jid misses the domain part
   */
  FileTransfer sendFile(Contact toContact, File file, String gw)
      throws IllegalStateException, IllegalArgumentException, OperationNotSupportedException {
    OutgoingFileTransferJabberImpl outgoingTransfer = null;

    try {
      assertConnected();

      if (file.length() > getMaximumFileLength())
        throw new IllegalArgumentException("File length exceeds the allowed one for this protocol");

      String fullJid = null;
      // Find the jid of the contact which support file transfer
      // and is with highest priority if more than one found
      // if we have equals priorities
      // choose the one that is more available
      OperationSetMultiUserChat mucOpSet =
          jabberProvider.getOperationSet(OperationSetMultiUserChat.class);
      if (mucOpSet != null && mucOpSet.isPrivateMessagingContact(toContact.getAddress())) {
        fullJid = toContact.getAddress();
      } else {
        Iterator<Presence> iter =
            jabberProvider.getConnection().getRoster().getPresences(toContact.getAddress());
        int bestPriority = -1;

        PresenceStatus jabberStatus = null;

        while (iter.hasNext()) {
          Presence presence = iter.next();

          if (jabberProvider.isFeatureListSupported(
              presence.getFrom(),
              new String[] {
                "http://jabber.org/protocol/si",
                "http://jabber.org/protocol/si/profile/file-transfer"
              })) {

            int priority =
                (presence.getPriority() == Integer.MIN_VALUE) ? 0 : presence.getPriority();

            if (priority > bestPriority) {
              bestPriority = priority;
              fullJid = presence.getFrom();
              jabberStatus =
                  OperationSetPersistentPresenceJabberImpl.jabberStatusToPresenceStatus(
                      presence, jabberProvider);
            } else if (priority == bestPriority && jabberStatus != null) {
              PresenceStatus tempStatus =
                  OperationSetPersistentPresenceJabberImpl.jabberStatusToPresenceStatus(
                      presence, jabberProvider);
              if (tempStatus.compareTo(jabberStatus) > 0) {
                fullJid = presence.getFrom();
                jabberStatus = tempStatus;
              }
            }
          }
        }
      }

      // First we check if file transfer is at all supported for this
      // contact.
      if (fullJid == null) {
        throw new OperationNotSupportedException(
            "Contact client or server does not support file transfers.");
      }

      if (gw != null && !fullJid.contains("@") && !fullJid.endsWith(gw)) {
        fullJid = fullJid + "@" + gw;
      }

      OutgoingFileTransfer transfer = manager.createOutgoingFileTransfer(fullJid);

      outgoingTransfer =
          new OutgoingFileTransferJabberImpl(toContact, file, transfer, jabberProvider);

      // Notify all interested listeners that a file transfer has been
      // created.
      FileTransferCreatedEvent event = new FileTransferCreatedEvent(outgoingTransfer, new Date());

      fireFileTransferCreated(event);

      // Send the file through the Jabber file transfer.
      transfer.sendFile(file, "Sending file");

      // Start the status and progress thread.
      new FileTransferProgressThread(transfer, outgoingTransfer).start();
    } catch (XMPPException e) {
      logger.error("Failed to send file.", e);
    }

    return outgoingTransfer;
  }
 /**
  * Utility method throwing an exception if the stack is not properly initialized.
  *
  * @throws java.lang.IllegalStateException if the underlying stack is not registered and
  *     initialized.
  */
 private void assertConnected() throws IllegalStateException {
   if (opSetPersPresence == null) {
     throw new IllegalStateException(
         "The provider must be signed on the service before" + " being able to communicate.");
   } else opSetPersPresence.assertConnected();
 }