/**
   * Construct a <tt>Request</tt> represent a new message.
   *
   * @param to the <tt>Contact</tt> to send <tt>message</tt> to
   * @param message the <tt>Message</tt> to send.
   * @return a Message Request destined to the contact
   * @throws OperationFailedException if an error occurred during the creation of the request
   */
  Request createMessageRequest(Contact to, Message message) throws OperationFailedException {
    Address toAddress = null;
    try {
      toAddress = sipProvider.parseAddressString(to.getAddress());
    } catch (ParseException exc) {
      // Shouldn't happen
      logger.error("An unexpected error occurred while" + "constructing the address", exc);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the address",
          OperationFailedException.INTERNAL_ERROR,
          exc);
    }

    // Call ID
    CallIdHeader callIdHeader = this.sipProvider.getDefaultJainSipProvider().getNewCallId();

    // CSeq
    CSeqHeader cSeqHeader = null;

    try {
      // protect seqN
      synchronized (this) {
        cSeqHeader = this.sipProvider.getHeaderFactory().createCSeqHeader(seqN++, Request.MESSAGE);
      }
    } catch (InvalidArgumentException ex) {
      // Shouldn't happen
      logger.error("An unexpected error occurred while" + "constructing the CSeqHeadder", ex);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the CSeqHeadder",
          OperationFailedException.INTERNAL_ERROR,
          ex);
    } catch (ParseException exc) {
      // shouldn't happen
      logger.error("An unexpected error occurred while" + "constructing the CSeqHeadder", exc);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the CSeqHeadder",
          OperationFailedException.INTERNAL_ERROR,
          exc);
    }

    // FromHeader and ToHeader
    String localTag = SipMessageFactory.generateLocalTag();
    FromHeader fromHeader = null;
    ToHeader toHeader = null;
    try {
      // FromHeader
      fromHeader =
          this.sipProvider
              .getHeaderFactory()
              .createFromHeader(sipProvider.getOurSipAddress(toAddress), localTag);

      // ToHeader
      toHeader = this.sipProvider.getHeaderFactory().createToHeader(toAddress, null);
    } catch (ParseException ex) {
      // these two should never happen.
      logger.error(
          "An unexpected error occurred while" + "constructing the FromHeader or ToHeader", ex);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the FromHeader or ToHeader",
          OperationFailedException.INTERNAL_ERROR,
          ex);
    }

    // ViaHeaders
    ArrayList<ViaHeader> viaHeaders = this.sipProvider.getLocalViaHeaders(toAddress);

    // MaxForwards
    MaxForwardsHeader maxForwards = this.sipProvider.getMaxForwardsHeader();

    // Content params
    ContentTypeHeader contTypeHeader;
    ContentLengthHeader contLengthHeader;
    try {
      contTypeHeader =
          this.sipProvider
              .getHeaderFactory()
              .createContentTypeHeader(getType(message), getSubType(message));

      if (!DEFAULT_MIME_ENCODING.equalsIgnoreCase(message.getEncoding()))
        contTypeHeader.setParameter("charset", message.getEncoding());

      contLengthHeader =
          this.sipProvider.getHeaderFactory().createContentLengthHeader(message.getSize());
    } catch (ParseException ex) {
      // these two should never happen.
      logger.error("An unexpected error occurred while" + "constructing the content headers", ex);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the content headers",
          OperationFailedException.INTERNAL_ERROR,
          ex);
    } catch (InvalidArgumentException exc) {
      // these two should never happen.
      logger.error(
          "An unexpected error occurred while" + "constructing the content length header", exc);
      throw new OperationFailedException(
          "An unexpected error occurred while" + "constructing the content length header",
          OperationFailedException.INTERNAL_ERROR,
          exc);
    }

    Request req;
    try {
      req =
          this.sipProvider
              .getMessageFactory()
              .createRequest(
                  toHeader.getAddress().getURI(),
                  Request.MESSAGE,
                  callIdHeader,
                  cSeqHeader,
                  fromHeader,
                  toHeader,
                  viaHeaders,
                  maxForwards,
                  contTypeHeader,
                  message.getRawData());
    } catch (ParseException ex) {
      // shouldn't happen
      logger.error("Failed to create message Request!", ex);
      throw new OperationFailedException(
          "Failed to create message Request!", OperationFailedException.INTERNAL_ERROR, ex);
    }

    req.addHeader(contLengthHeader);

    return req;
  }
  /**
   * Find the <tt>ProtocolProviderServiceSipImpl</tt> (one of our "candidate recipient" listeners)
   * which this <tt>request</tt> should be dispatched to. The strategy is to look first at the
   * request URI, and then at the To field to find a matching candidate for dispatching. Note that
   * this method takes a <tt>Request</tt> as param, and not a <tt>ServerTransaction</tt>, because
   * sometimes <tt>RequestEvent</tt>s have no associated <tt>ServerTransaction</tt>.
   *
   * @param request the <tt>Request</tt> to find a recipient for.
   * @return a suitable <tt>ProtocolProviderServiceSipImpl</tt>.
   */
  private ProtocolProviderServiceSipImpl findTargetFor(Request request) {
    if (request == null) {
      logger.error("request shouldn't be null.");
      return null;
    }

    List<ProtocolProviderServiceSipImpl> currentListenersCopy =
        new ArrayList<ProtocolProviderServiceSipImpl>(this.getSipListeners());

    // Let's first narrow down candidate choice by comparing
    // addresses and ports (no point in delivering to a provider with a
    // non matching IP address  since they will reject it anyway).
    filterByAddress(currentListenersCopy, request);

    if (currentListenersCopy.size() == 0) {
      logger.error("no listeners");
      return null;
    }

    URI requestURI = request.getRequestURI();

    if (requestURI.isSipURI()) {
      String requestUser = ((SipURI) requestURI).getUser();

      List<ProtocolProviderServiceSipImpl> candidates =
          new ArrayList<ProtocolProviderServiceSipImpl>();

      // check if the Request-URI username is
      // one of ours usernames
      for (ProtocolProviderServiceSipImpl listener : currentListenersCopy) {
        String ourUserID = listener.getAccountID().getUserID();
        // logger.trace(ourUserID + " *** " + requestUser);
        if (ourUserID.equals(requestUser)) {
          if (logger.isTraceEnabled())
            logger.trace("suitable candidate found: " + listener.getAccountID());
          candidates.add(listener);
        }
      }

      // the perfect match
      // every other case is approximation
      if (candidates.size() == 1) {
        ProtocolProviderServiceSipImpl perfectMatch = candidates.get(0);

        if (logger.isTraceEnabled())
          logger.trace("Will dispatch to \"" + perfectMatch.getAccountID() + "\"");
        return perfectMatch;
      }

      // more than one account match
      if (candidates.size() > 1) {
        // check if a custom param exists in the contact
        // address (set for registrar accounts)
        for (ProtocolProviderServiceSipImpl candidate : candidates) {
          String hostValue =
              ((SipURI) requestURI).getParameter(SipStackSharing.CONTACT_ADDRESS_CUSTOM_PARAM_NAME);
          if (hostValue == null) continue;
          if (hostValue.equals(candidate.getContactAddressCustomParamValue())) {
            if (logger.isTraceEnabled())
              logger.trace(
                  "Will dispatch to \""
                      + candidate.getAccountID()
                      + "\" because "
                      + "\" the custom param was set");
            return candidate;
          }
        }

        // Past this point, our guess is not reliable. We try to find
        // the "least worst" match based on parameters like the To field

        // check if the To header field host part
        // matches any of our SIP hosts
        for (ProtocolProviderServiceSipImpl candidate : candidates) {
          URI fromURI = ((FromHeader) request.getHeader(FromHeader.NAME)).getAddress().getURI();
          if (fromURI.isSipURI() == false) continue;
          SipURI ourURI = (SipURI) candidate.getOurSipAddress((SipURI) fromURI).getURI();
          String ourHost = ourURI.getHost();

          URI toURI = ((ToHeader) request.getHeader(ToHeader.NAME)).getAddress().getURI();
          if (toURI.isSipURI() == false) continue;
          String toHost = ((SipURI) toURI).getHost();

          // logger.trace(toHost + "***" + ourHost);
          if (toHost.equals(ourHost)) {
            if (logger.isTraceEnabled())
              logger.trace(
                  "Will dispatch to \""
                      + candidate.getAccountID()
                      + "\" because "
                      + "host in the To: is the same as in our AOR");
            return candidate;
          }
        }

        // fallback on the first candidate
        ProtocolProviderServiceSipImpl target = candidates.iterator().next();
        logger.info(
            "Will randomly dispatch to \""
                + target.getAccountID()
                + "\" because there is ambiguity on the username from"
                + " the Request-URI");
        if (logger.isTraceEnabled()) logger.trace("\n" + request);
        return target;
      }

      // fallback on any account
      ProtocolProviderServiceSipImpl target = currentListenersCopy.iterator().next();
      if (logger.isDebugEnabled())
        logger.debug(
            "Will randomly dispatch to \""
                + target.getAccountID()
                + "\" because the username in the Request-URI "
                + "is unknown or empty");
      if (logger.isTraceEnabled()) logger.trace("\n" + request);
      return target;
    } else {
      logger.error("Request-URI is not a SIP URI, dropping");
    }
    return null;
  }