/**
     * Returns <tt>true</tt> if <tt>packet</tt> is a <tt>Message</tt> and false otherwise.
     *
     * @param packet the packet that we need to check.
     * @return <tt>true</tt> if <tt>packet</tt> is a <tt>Message</tt> and false otherwise.
     */
    public boolean accept(Packet packet) {
      if (!(packet instanceof org.jivesoftware.smack.packet.Message)) return false;

      org.jivesoftware.smack.packet.Message msg = (org.jivesoftware.smack.packet.Message) packet;

      return !msg.getType().equals(org.jivesoftware.smack.packet.Message.Type.groupchat);
    }
    /**
     * Handles incoming messages and dispatches whatever events are necessary.
     *
     * @param packet the packet that we need to handle (if it is a message).
     */
    public void processPacket(Packet packet) {
      if (!(packet instanceof org.jivesoftware.smack.packet.Message)) return;

      org.jivesoftware.smack.packet.Message msg = (org.jivesoftware.smack.packet.Message) packet;

      boolean isForwardedSentMessage = false;
      if (msg.getBody() == null) {

        CarbonPacketExtension carbonExt =
            (CarbonPacketExtension) msg.getExtension(CarbonPacketExtension.NAMESPACE);
        if (carbonExt == null) return;

        isForwardedSentMessage =
            (carbonExt.getElementName() == CarbonPacketExtension.SENT_ELEMENT_NAME);
        List<ForwardedPacketExtension> extensions =
            carbonExt.getChildExtensionsOfType(ForwardedPacketExtension.class);
        if (extensions.isEmpty()) return;
        ForwardedPacketExtension forwardedExt = extensions.get(0);
        msg = forwardedExt.getMessage();
        if (msg == null || msg.getBody() == null) return;
      }

      Object multiChatExtension = msg.getExtension("x", "http://jabber.org/protocol/muc#user");

      // its not for us
      if (multiChatExtension != null) return;

      String userFullId = isForwardedSentMessage ? msg.getTo() : msg.getFrom();

      String userBareID = StringUtils.parseBareAddress(userFullId);

      boolean isPrivateMessaging = false;
      ChatRoom privateContactRoom = null;
      OperationSetMultiUserChatJabberImpl mucOpSet =
          (OperationSetMultiUserChatJabberImpl)
              jabberProvider.getOperationSet(OperationSetMultiUserChat.class);
      if (mucOpSet != null) privateContactRoom = mucOpSet.getChatRoom(userBareID);

      if (privateContactRoom != null) {
        isPrivateMessaging = true;
      }

      if (logger.isDebugEnabled()) {
        if (logger.isDebugEnabled())
          logger.debug("Received from " + userBareID + " the message " + msg.toXML());
      }

      Message newMessage = createMessage(msg.getBody(), DEFAULT_MIME_TYPE, msg.getPacketID());

      // check if the message is available in xhtml
      PacketExtension ext = msg.getExtension("http://jabber.org/protocol/xhtml-im");

      if (ext != null) {
        XHTMLExtension xhtmlExt = (XHTMLExtension) ext;

        // parse all bodies
        Iterator<String> bodies = xhtmlExt.getBodies();
        StringBuffer messageBuff = new StringBuffer();
        while (bodies.hasNext()) {
          String body = bodies.next();
          messageBuff.append(body);
        }

        if (messageBuff.length() > 0) {
          // we remove body tags around message cause their
          // end body tag is breaking
          // the visualization as html in the UI
          String receivedMessage =
              messageBuff
                  .toString()
                  // removes body start tag
                  .replaceAll("\\<[bB][oO][dD][yY].*?>", "")
                  // removes body end tag
                  .replaceAll("\\</[bB][oO][dD][yY].*?>", "");

          // for some reason &apos; is not rendered correctly
          // from our ui, lets use its equivalent. Other
          // similar chars(< > & ") seem ok.
          receivedMessage = receivedMessage.replaceAll("&apos;", "&#39;");

          newMessage = createMessage(receivedMessage, HTML_MIME_TYPE, msg.getPacketID());
        }
      }

      PacketExtension correctionExtension = msg.getExtension(MessageCorrectionExtension.NAMESPACE);
      String correctedMessageUID = null;
      if (correctionExtension != null) {
        correctedMessageUID =
            ((MessageCorrectionExtension) correctionExtension).getCorrectedMessageUID();
      }

      Contact sourceContact =
          opSetPersPresence.findContactByID((isPrivateMessaging ? userFullId : userBareID));
      if (msg.getType() == org.jivesoftware.smack.packet.Message.Type.error) {
        // error which is multichat and we don't know about the contact
        // is a muc message error which is missing muc extension
        // and is coming from the room, when we try to send message to
        // room which was deleted or offline on the server
        if (isPrivateMessaging && sourceContact == null) {
          if (privateContactRoom != null) {
            XMPPError error = packet.getError();
            int errorResultCode = ChatRoomMessageDeliveryFailedEvent.UNKNOWN_ERROR;

            if (error != null && error.getCode() == 403) {
              errorResultCode = ChatRoomMessageDeliveryFailedEvent.FORBIDDEN;
            }

            String errorReason = error.getMessage();

            ChatRoomMessageDeliveryFailedEvent evt =
                new ChatRoomMessageDeliveryFailedEvent(
                    privateContactRoom, null, errorResultCode, errorReason, new Date(), newMessage);
            ((ChatRoomJabberImpl) privateContactRoom).fireMessageEvent(evt);
          }

          return;
        }

        if (logger.isInfoEnabled()) logger.info("Message error received from " + userBareID);

        int errorResultCode = MessageDeliveryFailedEvent.UNKNOWN_ERROR;
        if (packet.getError() != null) {
          int errorCode = packet.getError().getCode();

          if (errorCode == 503) {
            org.jivesoftware.smackx.packet.MessageEvent msgEvent =
                (org.jivesoftware.smackx.packet.MessageEvent)
                    packet.getExtension("x", "jabber:x:event");
            if (msgEvent != null && msgEvent.isOffline()) {
              errorResultCode = MessageDeliveryFailedEvent.OFFLINE_MESSAGES_NOT_SUPPORTED;
            }
          }
        }

        if (sourceContact == null) {
          sourceContact = opSetPersPresence.createVolatileContact(userFullId, isPrivateMessaging);
        }

        MessageDeliveryFailedEvent ev =
            new MessageDeliveryFailedEvent(
                newMessage, sourceContact, correctedMessageUID, errorResultCode);

        // ev = messageDeliveryFailedTransform(ev);

        if (ev != null) fireMessageEvent(ev);
        return;
      }
      putJidForAddress(userFullId, msg.getThread());

      // In the second condition we filter all group chat messages,
      // because they are managed by the multi user chat operation set.
      if (sourceContact == null) {
        if (logger.isDebugEnabled())
          logger.debug("received a message from an unknown contact: " + userBareID);
        // create the volatile contact
        sourceContact = opSetPersPresence.createVolatileContact(userFullId, isPrivateMessaging);
      }

      Date timestamp = new Date();
      // Check for XEP-0091 timestamp (deprecated)
      PacketExtension delay = msg.getExtension("x", "jabber:x:delay");
      if (delay != null && delay instanceof DelayInformation) {
        timestamp = ((DelayInformation) delay).getStamp();
      }
      // check for XEP-0203 timestamp
      delay = msg.getExtension("delay", "urn:xmpp:delay");
      if (delay != null && delay instanceof DelayInfo) {
        timestamp = ((DelayInfo) delay).getStamp();
      }

      ContactResource resource = ((ContactJabberImpl) sourceContact).getResourceFromJid(userFullId);

      EventObject msgEvt = null;
      if (!isForwardedSentMessage)
        msgEvt =
            new MessageReceivedEvent(
                newMessage,
                sourceContact,
                resource,
                timestamp,
                correctedMessageUID,
                isPrivateMessaging,
                privateContactRoom);
      else msgEvt = new MessageDeliveredEvent(newMessage, sourceContact, timestamp);
      // msgReceivedEvt = messageReceivedTransform(msgReceivedEvt);
      if (msgEvt != null) fireMessageEvent(msgEvt);
    }
  /**
   * Helper function used to send a message to a contact, with the given extensions attached.
   *
   * @param to The contact to send the message to.
   * @param toResource The resource to send the message to or null if no resource has been specified
   * @param message The message to send.
   * @param extensions The XMPP extensions that should be attached to the message before sending.
   * @return The MessageDeliveryEvent that resulted after attempting to send this message, so the
   *     calling function can modify it if needed.
   */
  private MessageDeliveredEvent sendMessage(
      Contact to, ContactResource toResource, Message message, PacketExtension[] extensions) {
    if (!(to instanceof ContactJabberImpl))
      throw new IllegalArgumentException("The specified contact is not a Jabber contact." + to);

    assertConnected();

    org.jivesoftware.smack.packet.Message msg = new org.jivesoftware.smack.packet.Message();

    String toJID = null;

    if (toResource != null) {
      if (toResource.equals(ContactResource.BASE_RESOURCE)) {
        toJID = to.getAddress();
      } else toJID = ((ContactResourceJabberImpl) toResource).getFullJid();
    }

    if (toJID == null) {
      toJID = to.getAddress();
    }

    msg.setPacketID(message.getMessageUID());
    msg.setTo(toJID);

    for (PacketExtension ext : extensions) {
      msg.addExtension(ext);
    }

    if (logger.isTraceEnabled())
      logger.trace("Will send a message to:" + toJID + " chat.jid=" + toJID);

    MessageDeliveredEvent msgDeliveryPendingEvt =
        new MessageDeliveredEvent(message, to, toResource);

    MessageDeliveredEvent[] transformedEvents =
        messageDeliveryPendingTransform(msgDeliveryPendingEvt);

    if (transformedEvents == null || transformedEvents.length == 0) return null;

    for (MessageDeliveredEvent event : transformedEvents) {
      String content = event.getSourceMessage().getContent();

      if (message.getContentType().equals(HTML_MIME_TYPE)) {
        msg.setBody(Html2Text.extractText(content));

        // Check if the other user supports XHTML messages
        // make sure we use our discovery manager as it caches calls
        if (jabberProvider.isFeatureListSupported(toJID, HTML_NAMESPACE)) {
          // Add the XHTML text to the message
          XHTMLManager.addBody(msg, OPEN_BODY_TAG + content + CLOSE_BODY_TAG);
        }
      } else {
        // this is plain text so keep it as it is.
        msg.setBody(content);
      }

      // msg.addExtension(new Version());

      if (event.isMessageEncrypted() && isCarbonEnabled) {
        msg.addExtension(new CarbonPacketExtension.PrivateExtension());
      }

      MessageEventManager.addNotificationsRequests(msg, true, false, false, true);

      String threadID = getThreadIDForAddress(toJID);
      if (threadID == null) threadID = nextThreadID();

      msg.setThread(threadID);
      msg.setType(org.jivesoftware.smack.packet.Message.Type.chat);
      msg.setFrom(jabberProvider.getConnection().getUser());

      jabberProvider.getConnection().sendPacket(msg);

      putJidForAddress(toJID, threadID);
    }

    return new MessageDeliveredEvent(message, to, toResource);
  }