public Task Attach()

in src/NMS.AMQP/Provider/Amqp/AmqpConsumer.cs [66:124]
43 lines of code
14 McCabe index (conditional complexity)

        public Task Attach()
        {
            Target target = new Target();
            Source source = CreateSource();

            Attach attach = new Attach
            {
                Target = target,
                Source = source,
                RcvSettleMode = ReceiverSettleMode.First,
                SndSettleMode = (info.IsBrowser) ? SenderSettleMode.Settled : SenderSettleMode.Unsettled,
            };

            string receiverLinkName = null;

            string subscriptionName = info.SubscriptionName;
            if (!string.IsNullOrEmpty(subscriptionName))
            {
                AmqpConnection connection = session.Connection;

                if (info.IsShared && !connection.Info.SharedSubsSupported) {
                    validateSharedSubsLinkCapability = true;
                }

                AmqpSubscriptionTracker subTracker = connection.SubscriptionTracker;

                // Validate subscriber type allowed given existing active subscriber types.
                if (info.IsShared && info.IsDurable) {
                    if(subTracker.IsActiveExclusiveDurableSub(subscriptionName)) {
                        // Don't allow shared sub if there is already an active exclusive durable sub
                        throw new NMSException("A non-shared durable subscription is already active with name '" + subscriptionName + "'");
                    }
                } else if (!info.IsShared && info.IsDurable) {
                    if (subTracker.IsActiveExclusiveDurableSub(subscriptionName)) {
                        // Exclusive durable sub is already active
                        throw new NMSException("A non-shared durable subscription is already active with name '" + subscriptionName + "'");
                    } else if (subTracker.IsActiveSharedDurableSub(subscriptionName)) {
                        // Don't allow exclusive durable sub if there is already an active shared durable sub
                        throw new NMSException("A shared durable subscription is already active with name '" + subscriptionName + "'");
                    }
                }

                // Get the link name for the subscription. Throws if certain further validations fail.
                receiverLinkName = subTracker.ReserveNextSubscriptionLinkName(subscriptionName, info);
            }

            
            if (receiverLinkName == null) {
                string destinationAddress = source.Address ?? "";
                receiverLinkName = "nms:receiver:" + info.Id
                                                   + (destinationAddress.Length == 0 ? "" : (":" + destinationAddress));
            }

            // TODO: Add timeout
            var tsc = new TaskCompletionSource<bool>(TaskCreationOptions.RunContinuationsAsynchronously);
            receiverLink = new ReceiverLink(session.UnderlyingSession, receiverLinkName, attach, HandleOpened(tsc));
            receiverLink.AddClosedCallback(HandleClosed(tsc));
            return tsc.Task;
        }