private async Task CreateSessionAsync()

in iothub/service/src/Amqp/IotHubConnection.cs [253:351]
80 lines of code
7 McCabe index (conditional complexity)

        private async Task<AmqpSession> CreateSessionAsync(TimeSpan timeout)
        {
            Logging.Enter(this, timeout, nameof(CreateSessionAsync));

            TransportBase transport = null;

            try
            {
                var timeoutHelper = new TimeoutHelper(timeout);
                _refreshTokenTimer.Cancel();

                AmqpSettings amqpSettings = CreateAmqpSettings();
                if (_useWebSocketOnly)
                {
                    // Try only AMQP transport over WebSocket
                    transport = _clientWebSocketTransport = (ClientWebSocketTransport)await CreateClientWebSocketTransportAsync(timeoutHelper.RemainingTime())
                        .ConfigureAwait(false);
                }
                else
                {
                    TlsTransportSettings tlsTransportSettings = CreateTlsTransportSettings();
                    var amqpTransportInitiator = new AmqpTransportInitiator(amqpSettings, tlsTransportSettings);
                    try
                    {
                        transport = await amqpTransportInitiator.ConnectTaskAsync(timeoutHelper.RemainingTime()).ConfigureAwait(false);
                    }
                    catch (Exception e) when (!(e is AuthenticationException))
                    {
                        Logging.Error(this, e, nameof(CreateSessionAsync));

                        if (Fx.IsFatal(e))
                        {
                            throw;
                        }

                        // AMQP transport over TCP failed. Retry AMQP transport over WebSocket
                        if (timeoutHelper.RemainingTime() != TimeSpan.Zero)
                        {
                            transport = _clientWebSocketTransport = (ClientWebSocketTransport)await CreateClientWebSocketTransportAsync(timeoutHelper.RemainingTime()).ConfigureAwait(false);
                        }
                        else
                        {
                            throw;
                        }
                    }
                }

                Logging.Info(this, $"Initialized {nameof(TransportBase)}, ws={_useWebSocketOnly}");

                var amqpConnectionSettings = new AmqpConnectionSettings
                {
                    MaxFrameSize = AmqpConstants.DefaultMaxFrameSize,
                    ContainerId = Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture), // Use a human readable link name to help with debugging
                    HostName = Credential.AmqpEndpoint.Host,
                };

                var amqpConnection = new AmqpConnection(transport, amqpSettings, amqpConnectionSettings);
                await amqpConnection.OpenAsync(timeoutHelper.RemainingTime()).ConfigureAwait(false);

                Logging.Info(this, $"{nameof(AmqpConnection)} opened.");

                var sessionSettings = new AmqpSessionSettings
                {
                    Properties = new Fields(),
                };

                try
                {
                    AmqpSession amqpSession = amqpConnection.CreateSession(sessionSettings);
                    await amqpSession.OpenAsync(timeoutHelper.RemainingTime()).ConfigureAwait(false);

                    Logging.Info(this, $"{nameof(AmqpSession)} opened.");

                    // This adds itself to amqpConnection.Extensions
                    var cbsLink = new AmqpCbsLink(amqpConnection);
                    await SendCbsTokenAsync(cbsLink, timeoutHelper.RemainingTime()).ConfigureAwait(false);
                    return amqpSession;
                }
                catch (Exception ex) when (!ex.IsFatal())
                {
                    Logging.Error(this, ex, nameof(CreateSessionAsync));

                    _clientWebSocketTransport?.Dispose();
                    _clientWebSocketTransport = null;

                    if (amqpConnection.TerminalException != null)
                    {
                        throw AmqpClientHelper.ToIotHubClientContract(amqpConnection.TerminalException);
                    }

                    amqpConnection.SafeClose(ex);
                    throw;
                }
            }
            finally
            {
                Logging.Exit(this, timeout, nameof(CreateSessionAsync));
            }
        }