/**
   * {@inheritDoc} VirtualFirealarm device-type specific implementation to publish data to the
   * device. This method calls the {@link #publishToQueue(String, MqttMessage)} method of the
   * "MQTTTransportHandler" class.
   */
  @Override
  public void publishDeviceData(String... publishData) throws TransportHandlerException {
    if (publishData.length != 4) {
      String errorMsg =
          "Incorrect number of arguments received to SEND-MQTT Message. "
              + "Need to be [owner, deviceId, resource{BULB/TEMP}, state{ON/OFF or null}]";
      log.error(errorMsg);
      throw new TransportHandlerException(errorMsg);
    }

    String deviceOwner = publishData[0];
    String deviceId = publishData[1];
    String resource = publishData[2];
    String state = publishData[3];

    MqttMessage pushMessage = new MqttMessage();
    String publishTopic = "wso2/" + VirtualFireAlarmConstants.DEVICE_TYPE + "/" + deviceId;

    try {
      PublicKey devicePublicKey = VirtualFireAlarmServiceUtils.getDevicePublicKey(deviceId);
      PrivateKey serverPrivateKey = SecurityManager.getServerPrivateKey();

      String actualMessage = resource + ":" + state;
      String encryptedMsg =
          VirtualFireAlarmServiceUtils.prepareSecurePayLoad(
              actualMessage, devicePublicKey, serverPrivateKey);

      pushMessage.setPayload(encryptedMsg.getBytes(StandardCharsets.UTF_8));
      pushMessage.setQos(DEFAULT_MQTT_QUALITY_OF_SERVICE);
      pushMessage.setRetained(false);

      publishToQueue(publishTopic, pushMessage);

    } catch (VirtualFireAlarmException e) {
      String errorMsg =
          "Preparing Secure payload failed for device - ["
              + deviceId
              + "] of owner - "
              + "["
              + deviceOwner
              + "].";
      log.error(errorMsg);
      throw new TransportHandlerException(errorMsg, e);
    }
  }
  /**
   * {@inheritDoc} VirtualFirealarm device-type specific implementation to process incoming
   * messages. This is the specific method signature of the overloaded "processIncomingMessage"
   * method that gets called from the messageArrived() callback of the "MQTTTransportHandler".
   */
  @Override
  public void processIncomingMessage(MqttMessage mqttMessage, String... messageParams) {
    if (messageParams.length != 0) {
      // owner and the deviceId are extracted from the MQTT topic to which the message was received.
      // <Topic> = [ServerName/Owner/DeviceType/DeviceId/"publisher"]
      String topic = messageParams[0];
      String[] topicParams = topic.split("/");
      String deviceId = topicParams[2];
      if (log.isDebugEnabled()) {
        log.debug("Received MQTT message for: [DEVICE.ID-" + deviceId + "]");
      }

      String actualMessage;
      try {
        // the hash-code of the deviceId is used as the alias for device certificates during SCEP
        // enrollment.
        // hence, the same is used here to fetch the device-specific-certificate from the key store.
        PublicKey clientPublicKey = VirtualFireAlarmServiceUtils.getDevicePublicKey(deviceId);
        PrivateKey serverPrivateKey = SecurityManager.getServerPrivateKey();

        // the MQTT-messages from VirtualFireAlarm devices are in the form {"Msg":<MESSAGE>,
        // "Sig":<SIGNATURE>}
        actualMessage =
            VirtualFireAlarmServiceUtils.extractMessageFromPayload(
                mqttMessage.toString(), serverPrivateKey, clientPublicKey);
        if (log.isDebugEnabled()) {
          log.debug("MQTT: Received Message [" + actualMessage + "] topic: [" + topic + "]");
        }

        if (actualMessage.contains("PUBLISHER")) {
          float temperature = Float.parseFloat(actualMessage.split(":")[2]);
          try {
            PrivilegedCarbonContext.startTenantFlow();
            PrivilegedCarbonContext ctx = PrivilegedCarbonContext.getThreadLocalCarbonContext();
            DeviceManagementProviderService deviceManagementProviderService =
                (DeviceManagementProviderService)
                    ctx.getOSGiService(DeviceManagementProviderService.class, null);
            if (deviceManagementProviderService != null) {
              DeviceIdentifier identifier =
                  new DeviceIdentifier(deviceId, VirtualFireAlarmConstants.DEVICE_TYPE);
              Device device = deviceManagementProviderService.getDevice(identifier);
              if (device != null) {
                String owner = device.getEnrolmentInfo().getOwner();
                ctx.setTenantDomain(MultitenantUtils.getTenantDomain(owner), true);
                ctx.setUsername(owner);
                if (!VirtualFireAlarmServiceUtils.publishToDAS(deviceId, temperature)) {
                  log.error("MQTT Subscriber: Publishing data to DAS failed.");
                }
              }
            }
          } catch (DeviceManagementException e) {
            log.error(
                "Failed to retreive the device managment service for device type "
                    + VirtualFireAlarmConstants.DEVICE_TYPE,
                e);
          } finally {
            PrivilegedCarbonContext.endTenantFlow();
          }
          if (log.isDebugEnabled()) {
            log.debug("MQTT Subscriber: Published data to DAS successfully.");
          }

        } else if (actualMessage.contains("TEMPERATURE")) {
          String temperatureValue = actualMessage.split(":")[1];
        }
      } catch (VirtualFireAlarmException e) {
        String errorMsg =
            "CertificateManagementService failure oo Signature-Verification/Decryption was unsuccessful.";
        log.error(errorMsg, e);
      }
    } else {
      String errorMsg =
          "MQTT message ["
              + mqttMessage.toString()
              + "] was received without the topic information.";
      log.warn(errorMsg);
    }
  }