public void AttachLink()

in src/AmqpSession.cs [117:179]
50 lines of code
11 McCabe index (conditional complexity)

        public void AttachLink(AmqpLink link)
        {
            Fx.Assert(link.Session == this, "The link is not owned by this session.");
            AmqpLink linkToSteal;

            lock (this.ThisLock)
            {
                if (this.IsClosing())
                {
                    throw new InvalidOperationException(AmqpResources.GetString(AmqpResources.AmqpIllegalOperationState, "attach", this.State));
                }

                if (this.links.TryGetValue(link.LinkIdentifier, out linkToSteal) && link.AllowLinkStealing(linkToSteal.Settings))
                {
                    // Even though link onclose handler already removes the link from the links collections,
                    // calling Close() is fire and forget, so we will not be waiting for the link onClose handler to trigger
                    // before trying to add the new link to the links collections down below in this method, therefore remove it now.
                    this.links.Remove(link.LinkIdentifier);
                    if (linkToSteal.LocalHandle.HasValue)
                    {
                        this.linksByLocalHandle.Remove(linkToSteal.LocalHandle.Value);
                    }

                    if (linkToSteal.RemoteHandle.HasValue)
                    {
                        this.linksByRemoteHandle.Remove(linkToSteal.RemoteHandle.Value);
                    }
                }
                else
                {
                    linkToSteal = null;
                }

                if (this.Connection.LinkRecoveryEnabled)
                {
                    bool foundTerminus = this.Connection.TerminusStore.TryGetLinkTerminusAsync(link.LinkIdentifier, out AmqpLinkTerminus linkTerminus).Result;
                    if (linkTerminus == null)
                    {
                        linkTerminus = new AmqpLinkTerminus(link.LinkIdentifier, link.Settings, this.Connection.TerminusStore);
                        if (!this.Connection.TerminusStore.TryAddLinkTerminusAsync(link.LinkIdentifier, linkTerminus).GetAwaiter().GetResult())
                        {
                            // There was a race and some other link has already created a link terminus and attach.
                            // In this case, stop opening of this link and close it due to link stealing.
                            throw new AmqpException(AmqpErrorCode.Stolen, AmqpResources.GetString(AmqpResources.AmqpLinkStolen, link.LinkIdentifier));
                        }
                    }

                    if (!linkTerminus.TryAssociateLink(link, out linkToSteal))
                    {
                        throw new InvalidOperationException("The link terminus to attach this link to is either disposed or link stealing is not allowed.");
                    }
                }

                link.Closed += onLinkClosed;
                this.links.Add(link.LinkIdentifier, link);
                link.LocalHandle = this.linksByLocalHandle.Add(link);
            }

            linkToSteal?.OnLinkStolen();

            AmqpTrace.Provider.AmqpAttachLink(this.connection, this, link, link.LocalHandle.Value,
                link.RemoteHandle ?? 0u, link.Name, link.IsReceiver ? "receiver" : "sender", link.Settings.Source, link.Settings.Target);
        }