internal static InternalClient Create()

in iothub/device/src/ClientFactory.cs [83:155]
61 lines of code
15 McCabe index (conditional complexity)

        internal static InternalClient Create(
            string hostname,
            string gatewayHostname,
            IAuthenticationMethod authenticationMethod,
            TransportType transportType,
            ClientOptions options = default)
        {
            if (hostname == null)
            {
                throw new ArgumentNullException(nameof(hostname));
            }

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

            if (transportType != TransportType.Amqp_Tcp_Only
                && transportType != TransportType.Mqtt_Tcp_Only
                && authenticationMethod is DeviceAuthenticationWithX509Certificate certificate
                && certificate.ChainCertificates != null)
            {
                throw new ArgumentException("Certificate chains are only supported on Amqp_Tcp_Only and Mqtt_Tcp_Only");
            }

            if (!string.IsNullOrWhiteSpace(options?.ModelId)
                && transportType == TransportType.Http1)
            {
                throw new InvalidOperationException("Plug and Play is not supported over the HTTP transport.");
            }

            var connectionStringBuilder = IotHubConnectionStringBuilder.Create(hostname, gatewayHostname, authenticationMethod);

            // Make sure client options is initialized with the correct transport setting.
            EnsureOptionsIsSetup(connectionStringBuilder.Certificate, ref options);

            if (authenticationMethod is DeviceAuthenticationWithX509Certificate)
            {
                if (connectionStringBuilder.Certificate == null)
                {
                    throw new ArgumentException("No certificate was found. To use certificate authentication certificate must be present.");
                }

                InternalClient internalClient = CreateFromConnectionString(
                    connectionStringBuilder.ToString(),
                    authenticationMethod,
                    PopulateCertificateInTransportSettings(connectionStringBuilder, transportType),
                    null,
                    options);

                internalClient.Certificate = connectionStringBuilder.Certificate;

                // Install all the intermediate certificates in the chain if specified.
                if (connectionStringBuilder.ChainCertificates != null)
                {
                    try
                    {
                        CertificateInstaller.EnsureChainIsInstalled(connectionStringBuilder.ChainCertificates);
                    }
                    catch (Exception ex)
                    {
                        if (Logging.IsEnabled)
                            Logging.Error(null, $"{nameof(CertificateInstaller)} failed to read or write to cert store due to: {ex}");

                        throw new UnauthorizedException($"Failed to provide certificates in the chain - {ex.Message}", ex);
                    }
                }

                return internalClient;
            }

            return CreateFromConnectionString(connectionStringBuilder.ToString(), authenticationMethod, transportType, null, options);
        }