public void onMessageArrived()

in iothub/device/iot-device-client/src/main/java/com/microsoft/azure/sdk/iot/device/transport/mqtt/MqttIotHubConnection.java [442:507]
59 lines of code
10 McCabe index (conditional complexity)

    public void onMessageArrived(int messageId)
    {
        IotHubTransportMessage transportMessage = this.directMethod.receive();
        if (transportMessage != null)
        {
            log.trace("Received MQTT device method message ({})", transportMessage);
        }
        else
        {
            transportMessage = deviceTwin.receive();
            if (transportMessage != null)
            {
                log.trace("Received MQTT device twin message ({})", transportMessage);
            }
            else
            {
                transportMessage = deviceMessaging.receive();
                if (transportMessage != null)
                {
                    log.trace("Received MQTT device messaging message ({})", transportMessage);
                }
            }
        }

        if (transportMessage == null)
        {
            //Ack is not sent to service for this message because we cannot interpret the message. Service will likely re-send
            this.listener.onMessageReceived(null, new TransportException("Message sent from service could not be parsed"));
            log.warn("Received message that could not be parsed. That message has been ignored.");
        }
        else
        {
            if (transportMessage.getQualityOfService() == 0)
            {
                // Direct method messages and Twin messages are always sent with QoS 0, so there is no need for this SDK
                // to acknowledge them.
                log.trace("MQTT received message with QoS 0 so it has not been added to the messages to acknowledge list ({})", transportMessage);
            }
            else
            {
                log.trace("MQTT received message so it has been added to the messages to acknowledge list ({})", transportMessage);
                this.receivedMessagesToAcknowledge.put(transportMessage, messageId);
            }

            switch (transportMessage.getMessageType())
            {
                case DEVICE_TWIN:
                    transportMessage.setMessageCallback(this.config.getDeviceTwinMessageCallback());
                    transportMessage.setMessageCallbackContext(this.config.getDeviceTwinMessageContext());
                    break;
                case DEVICE_METHODS:
                    transportMessage.setMessageCallback(this.config.getDirectMethodsMessageCallback());
                    transportMessage.setMessageCallbackContext(this.config.getDirectMethodsMessageContext());
                    break;
                case DEVICE_TELEMETRY:
                    transportMessage.setMessageCallback(this.config.getDeviceTelemetryMessageCallback(transportMessage.getInputName()));
                    transportMessage.setMessageCallbackContext(this.config.getDeviceTelemetryMessageContext(transportMessage.getInputName()));
                    break;
                case UNKNOWN:
                default:
                    //do nothing
            }

            this.listener.onMessageReceived(transportMessage, null);
        }
    }