public override async Task RegisterAsync()

in provisioning/transport/mqtt/src/ProvisioningTransportHandlerMqtt.cs [91:165]
66 lines of code
15 McCabe index (conditional complexity)

        public override async Task<DeviceRegistrationResult> RegisterAsync(
            ProvisioningTransportRegisterMessage message,
            CancellationToken cancellationToken)
        {
            if (Logging.IsEnabled)
                Logging.Enter(this, $"{nameof(ProvisioningTransportHandlerMqtt)}.{nameof(RegisterAsync)}");

            if (message == null)
            {
                throw new ArgumentNullException(nameof(message));
            }

            cancellationToken.ThrowIfCancellationRequested();

            RegistrationOperationStatus operation = null;

            try
            {
                if (message.Security is SecurityProviderX509 x509Security)
                {
                    if (FallbackType == TransportFallbackType.TcpWithWebSocketFallback || FallbackType == TransportFallbackType.TcpOnly)
                    {
                        // TODO: Fallback not implemented.
                        operation = await ProvisionOverTcpUsingX509CertificateAsync(message, cancellationToken).ConfigureAwait(false);
                    }
                    else if (FallbackType == TransportFallbackType.WebSocketOnly)
                    {
                        operation = await ProvisionOverWssUsingX509CertificateAsync(message, cancellationToken).ConfigureAwait(false);
                    }
                    else
                    {
                        throw new NotSupportedException($"Not supported {nameof(FallbackType)} value: {FallbackType}");
                    }
                }
                else if (message.Security is SecurityProviderSymmetricKey symmetricKeySecurity)
                {
                    if (FallbackType == TransportFallbackType.TcpWithWebSocketFallback ||
                        FallbackType == TransportFallbackType.TcpOnly)
                    {
                        // TODO: Fallback not implemented.
                        operation = await ProvisionOverTcpUsingSymmetricKeyAsync(message, cancellationToken).ConfigureAwait(false);
                    }
                    else if (FallbackType == TransportFallbackType.WebSocketOnly)
                    {
                        operation = await ProvisionOverWssUsingSymmetricKeyAsync(message, cancellationToken).ConfigureAwait(false);
                    }
                    else
                    {
                        throw new NotSupportedException($"Not supported {nameof(FallbackType)} value: {FallbackType}");
                    }
                }
                else
                {
                    if (Logging.IsEnabled)
                        Logging.Error(this, $"Invalid {nameof(SecurityProvider)} type.");

                    throw new NotSupportedException(
                        $"{nameof(message.Security)} must be of type {nameof(SecurityProviderX509)} or {nameof(SecurityProviderSymmetricKey)}");
                }

                return ConvertToProvisioningRegistrationResult(operation.RegistrationState);
            }
            catch (Exception ex) when (!(ex is ProvisioningTransportException))
            {
                if (Logging.IsEnabled)
                    Logging.Error(this, $"{nameof(ProvisioningTransportHandlerMqtt)} threw exception {ex}", nameof(RegisterAsync));

                throw new ProvisioningTransportException($"MQTT transport exception", ex, true);
            }
            finally
            {
                if (Logging.IsEnabled)
                    Logging.Exit(this, $"{nameof(ProvisioningTransportHandlerMqtt)}.{nameof(RegisterAsync)}");
            }
        }