/**
   * When a provider is added. As searching can be slow especially when handling special type of
   * messages (with subType) this need to be run in new Thread.
   *
   * @param provider ProtocolProviderService
   */
  private void handleProviderAddedInSeparateThread(
      ProtocolProviderService provider, boolean isStatusChanged) {
    // lets check if we have cached recent messages for this provider, and
    // fire events if found and are newer

    synchronized (recentMessages) {
      List<ComparableEvtObj> cachedRecentMessages =
          getCachedRecentMessages(provider, isStatusChanged);

      if (cachedRecentMessages.isEmpty()) {
        // maybe there is no cached history for this
        // let's check
        // load it not from cache, but do a local search
        Collection<EventObject> res =
            messageHistoryService.findRecentMessagesPerContact(
                numberOfMessages, provider.getAccountID().getAccountUniqueID(), null, isSMSEnabled);

        List<ComparableEvtObj> newMsc = new ArrayList<ComparableEvtObj>();

        processEventObjects(res, newMsc, isStatusChanged);

        addNewRecentMessages(newMsc);

        for (ComparableEvtObj msc : newMsc) {
          saveRecentMessageToHistory(msc);
        }
      } else addNewRecentMessages(cachedRecentMessages);
    }
  }
  /**
   * Searches for entries in cached recent messages in history.
   *
   * @param provider the provider which contact messages we will search
   * @param isStatusChanged is the search because of status changed
   * @return entries in cached recent messages in history.
   */
  private List<ComparableEvtObj> getCachedRecentMessages(
      ProtocolProviderService provider, boolean isStatusChanged) {
    String providerID = provider.getAccountID().getAccountUniqueID();
    List<String> recentMessagesContactIDs =
        getRecentContactIDs(
            providerID, recentMessages.size() < numberOfMessages ? null : oldestRecentMessage);

    List<ComparableEvtObj> cachedRecentMessages = new ArrayList<ComparableEvtObj>();

    for (String contactID : recentMessagesContactIDs) {
      Collection<EventObject> res =
          messageHistoryService.findRecentMessagesPerContact(
              numberOfMessages, providerID, contactID, isSMSEnabled);

      processEventObjects(res, cachedRecentMessages, isStatusChanged);
    }

    return cachedRecentMessages;
  }
  /**
   * A provider has been removed.
   *
   * @param provider the ProtocolProviderService that has been unregistered.
   */
  void handleProviderRemoved(ProtocolProviderService provider) {
    // lets remove the recent messages for this provider, and update
    // with recent messages for the available providers
    synchronized (recentMessages) {
      if (provider != null) {
        List<ComparableEvtObj> removedItems = new ArrayList<ComparableEvtObj>();
        for (ComparableEvtObj msc : recentMessages) {
          if (msc.getProtocolProviderService().equals(provider)) removedItems.add(msc);
        }

        recentMessages.removeAll(removedItems);
        if (!recentMessages.isEmpty())
          oldestRecentMessage = recentMessages.get(recentMessages.size() - 1).getTimestamp();
        else oldestRecentMessage = null;

        if (recentQuery != null) {
          for (ComparableEvtObj msc : removedItems) {
            recentQuery.fireContactRemoved(msc);
          }
        }
      }

      // handleProviderRemoved can be invoked due to stopped
      // history service, if this is the case we do not want to
      // update messages
      if (!this.messageHistoryService.isHistoryLoggingEnabled()) return;

      // lets do the same as we enable provider
      // for all registered providers and finally fire events
      List<ComparableEvtObj> contactsToAdd = new ArrayList<ComparableEvtObj>();
      for (ProtocolProviderService pps : messageHistoryService.getCurrentlyAvailableProviders()) {
        contactsToAdd.addAll(getCachedRecentMessages(pps, true));
      }

      addNewRecentMessages(contactsToAdd);
    }
  }