/**
   * Add a record telling what entity caps node a user has.
   *
   * @param user the user (Full JID)
   * @param node the node (of the caps packet extension)
   * @param hash the hashing algorithm used to calculate <tt>ver</tt>
   * @param ver the version (of the caps packet extension)
   * @param ext the ext (of the caps packet extension)
   * @param online indicates if the user is online
   */
  private void addUserCapsNode(
      String user, String node, String hash, String ver, String ext, boolean online) {
    if ((user != null) && (node != null) && (hash != null) && (ver != null)) {
      Caps caps = userCaps.get(user);

      if ((caps == null)
          || !caps.node.equals(node)
          || !caps.hash.equals(hash)
          || !caps.ver.equals(ver)) {
        caps = new Caps(node, hash, ver, ext);

        userCaps.put(user, caps);
      } else return;

      // Fire userCapsNodeAdded.
      UserCapsNodeListener[] listeners;

      synchronized (userCapsNodeListeners) {
        listeners = userCapsNodeListeners.toArray(NO_USER_CAPS_NODE_LISTENERS);
      }
      if (listeners.length != 0) {
        String nodeVer = caps.getNodeVer();

        for (UserCapsNodeListener listener : listeners)
          listener.userCapsNodeAdded(user, nodeVer, online);
      }
    }
  }
  /**
   * Add {@link DiscoverInfo} to our caps database.
   *
   * <p><b>Warning</b>: The specified <tt>DiscoverInfo</tt> is trusted to be valid with respect to
   * the specified <tt>Caps</tt> for performance reasons because the <tt>DiscoverInfo</tt> should
   * have already been validated in order to be used elsewhere anyway.
   *
   * @param caps the <tt>Caps<tt/> i.e. the node, the hash and the ver for which a
   *     <tt>DiscoverInfo</tt> is to be added to our caps database.
   * @param info {@link DiscoverInfo} for the specified <tt>Caps</tt>.
   */
  public static void addDiscoverInfoByCaps(Caps caps, DiscoverInfo info) {
    cleanupDiscoverInfo(info);
    /*
     * DiscoverInfo carries the node we're now associating it with a
     * specific node so we'd better keep them in sync.
     */
    info.setNode(caps.getNodeVer());

    synchronized (caps2discoverInfo) {
      DiscoverInfo oldInfo = caps2discoverInfo.put(caps, info);

      /*
       * If the specified info is a new association for the specified
       * node, remember it across application instances in order to not
       * query for it over the network.
       */
      if ((oldInfo == null) || !oldInfo.equals(info)) {
        String xml = info.getChildElementXML();

        if ((xml != null) && (xml.length() != 0)) {
          getConfigService().setProperty(getCapsPropertyName(caps), xml);
        }
      }
    }
  }
  /**
   * Maps the specified <tt>address</tt> to <tt>jid</tt>. The point of this method is to allow us to
   * send all messages destined to the contact with the specified <tt>address</tt> to the
   * <tt>jid</tt> that they last contacted us from.
   *
   * @param threadID the threadID of conversation.
   * @param jid the jid (i.e. address/resource) that the contact with the specified <tt>address</tt>
   *     last contacted us from.
   */
  private void putJidForAddress(String jid, String threadID) {
    synchronized (jids) {
      purgeOldJids();

      StoredThreadID ta = jids.get(jid);

      if (ta == null) {
        ta = new StoredThreadID();
        jids.put(jid, ta);
      }

      recentJIDForAddress.put(StringUtils.parseBareAddress(jid), jid);

      ta.lastUpdatedTime = System.currentTimeMillis();
      ta.threadID = threadID;
    }
  }
  /**
   * Retrieve DiscoverInfo for a specific node.
   *
   * @param caps the <tt>Caps</tt> i.e. the node, the hash and the ver
   * @return The corresponding DiscoverInfo or null if none is known.
   */
  public static DiscoverInfo getDiscoverInfoByCaps(Caps caps) {
    synchronized (caps2discoverInfo) {
      DiscoverInfo discoverInfo = caps2discoverInfo.get(caps);

      /*
       * If we don't have the discoverInfo in the runtime cache yet, we
       * may have it remembered in a previous application instance.
       */
      if (discoverInfo == null) {
        ConfigurationService configurationService = getConfigService();
        String capsPropertyName = getCapsPropertyName(caps);
        String xml = configurationService.getString(capsPropertyName);

        if ((xml != null) && (xml.length() != 0)) {
          IQProvider discoverInfoProvider =
              (IQProvider)
                  ProviderManager.getInstance()
                      .getIQProvider("query", "http://jabber.org/protocol/disco#info");

          if (discoverInfoProvider != null) {
            XmlPullParser parser = new MXParser();

            try {
              parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
              parser.setInput(new StringReader(xml));
              // Start the parser.
              parser.next();
            } catch (XmlPullParserException xppex) {
              parser = null;
            } catch (IOException ioex) {
              parser = null;
            }

            if (parser != null) {
              try {
                discoverInfo = (DiscoverInfo) discoverInfoProvider.parseIQ(parser);
              } catch (Exception ex) {
              }

              if (discoverInfo != null) {
                if (caps.isValid(discoverInfo)) caps2discoverInfo.put(caps, discoverInfo);
                else {
                  logger.error(
                      "Invalid DiscoverInfo for " + caps.getNodeVer() + ": " + discoverInfo);
                  /*
                   * The discoverInfo doesn't seem valid
                   * according to the caps which means that we
                   * must have stored invalid information.
                   * Delete the invalid information in order
                   * to not try to validate it again.
                   */
                  configurationService.removeProperty(capsPropertyName);
                }
              }
            }
          }
        }
      }
      return discoverInfo;
    }
  }