/**
   * Searches for contact ids in history of recent messages.
   *
   * @param provider
   * @param after
   * @return
   */
  List<String> getRecentContactIDs(String provider, Date after) {
    List<String> res = new ArrayList<String>();

    try {
      History history = getHistory();

      if (history != null) {
        Iterator<HistoryRecord> recs = history.getReader().findLast(NUMBER_OF_MSGS_IN_HISTORY);
        SimpleDateFormat sdf = new SimpleDateFormat(HistoryService.DATE_FORMAT);

        while (recs.hasNext()) {
          HistoryRecord hr = recs.next();

          String contact = null;
          String recordProvider = null;
          Date timestamp = null;

          for (int i = 0; i < hr.getPropertyNames().length; i++) {
            String propName = hr.getPropertyNames()[i];

            if (propName.equals(STRUCTURE_NAMES[0])) recordProvider = hr.getPropertyValues()[i];
            else if (propName.equals(STRUCTURE_NAMES[1])) contact = hr.getPropertyValues()[i];
            else if (propName.equals(STRUCTURE_NAMES[2])) {
              try {
                timestamp = sdf.parse(hr.getPropertyValues()[i]);
              } catch (ParseException e) {
                timestamp = new Date(Long.parseLong(hr.getPropertyValues()[i]));
              }
            }
          }

          if (recordProvider == null || contact == null) continue;

          if (after != null && timestamp != null && timestamp.before(after)) continue;

          if (recordProvider.equals(provider)) res.add(contact);
        }
      }
    } catch (IOException ex) {
      logger.error("cannot create recent_messages history", ex);
    }

    return res;
  }
  /** Adds recent message in history. */
  private void saveRecentMessageToHistory(ComparableEvtObj msc) {
    synchronized (historyID) {
      // and create it
      try {
        History history = getHistory();
        HistoryWriter writer = history.getWriter();

        SimpleDateFormat sdf = new SimpleDateFormat(HistoryService.DATE_FORMAT);

        writer.addRecord(
            new String[] {
              msc.getProtocolProviderService().getAccountID().getAccountUniqueID(),
              msc.getContactAddress(),
              sdf.format(msc.getTimestamp()),
              RECENT_MSGS_VER
            },
            NUMBER_OF_MSGS_IN_HISTORY);
      } catch (IOException ex) {
        logger.error("cannot create recent_messages history", ex);
        return;
      }
    }
  }