private void UnregisterEventListener()

in src/Desktop/UIAutomation/EventHandlers/EventListenerFactory.cs [224:335]
105 lines of code
18 McCabe index (conditional complexity)

        private void UnregisterEventListener(EventListenerFactoryMessage msgData)
        {
            HandleUIAutomationEventMessage listener = null;
            try
            {
                switch (msgData.EventId)
                {
                    case EventType.UIA_AutomationFocusChangedEventId:
                        if (this.EventListenerFocusChanged != null)
                        {
                            listener = this.EventListenerFocusChanged.ListenEventMessage;
                            this.EventListenerFocusChanged.Dispose();
                            this.EventListenerFocusChanged = null;
                        }
                        break;
                    case EventType.UIA_StructureChangedEventId:
                        if (this.EventListenerStructureChanged != null)
                        {
                            listener = this.EventListenerStructureChanged.ListenEventMessage;
                            this.EventListenerStructureChanged.Dispose();
                            this.EventListenerStructureChanged = null;
                        }
                        break;
                    case EventType.UIA_AutomationPropertyChangedEventId:
                        if (this.EventListenerPropertyChanged != null)
                        {
                            listener = this.EventListenerPropertyChanged.ListenEventMessage;
                            this.EventListenerPropertyChanged.Dispose();
                            this.EventListenerPropertyChanged = null;
                        }
                        break;
                    case EventType.UIA_TextEdit_TextChangedEventId:
                        if (this.EventListenerTextEditTextChanged != null)
                        {
                            listener = this.EventListenerTextEditTextChanged.ListenEventMessage;
                            this.EventListenerTextEditTextChanged.Dispose();
                            this.EventListenerTextEditTextChanged = null;
                        }
                        break;
                    case EventType.UIA_ChangesEventId:
                        if (this.EventListenerChanges != null)
                        {
                            listener = this.EventListenerChanges.ListenEventMessage;
                            this.EventListenerChanges.Dispose();
                            this.EventListenerChanges = null;
                        }
                        break;
                    case EventType.UIA_NotificationEventId:
                        if (this.EventListenerNotification != null)
                        {
                            listener = this.EventListenerNotification.ListenEventMessage;
                            this.EventListenerNotification.Dispose();
                            this.EventListenerNotification = null;
                        }
                        break;
                    case EventType.UIA_ActiveTextPositionChangedEventId:
                        if (this.EventListenerActiveTextPositionChanged != null)
                        {
                            listener = this.EventListenerActiveTextPositionChanged.ListenEventMessage;
                            this.EventListenerActiveTextPositionChanged.Dispose();
                            this.EventListenerActiveTextPositionChanged = null;
                        }
                        break;
                    default:
                        if (this.EventListeners.ContainsKey(msgData.EventId))
                        {
                            var l = this.EventListeners[msgData.EventId];
                            listener = l.ListenEventMessage;
                            this.EventListeners.Remove(msgData.EventId);
                            l.Dispose();
                        }
                        break;
                }

                if (listener != null)
                {
#pragma warning disable CA2000 // Call IDisposable.Dispose()
                    var m = EventMessage.GetInstance(EventType.UIA_EventRecorderNotificationEventId, null);
#pragma warning restore CA2000

                    m.Properties = new List<KeyValuePair<string, dynamic>>()
                    {
                        new KeyValuePair<string, dynamic>("Message", "Succeeded to unregister a event listeners"),
                        new KeyValuePair<string, dynamic>("Event Id", msgData.EventId),
                        new KeyValuePair<string, dynamic>("Event Name", EventType.GetInstance().GetNameById(msgData.EventId)),
                    };
                    listener(m);
                }
            }
#pragma warning disable CA1031 // Do not catch general exception types
            catch (Exception e)
            {
                e.ReportException();

#pragma warning disable CA2000 // Call IDisposable.Dispose()
                var m = EventMessage.GetInstance(EventType.UIA_EventRecorderNotificationEventId, null);
#pragma warning restore CA2000

                m.Properties = new List<KeyValuePair<string, dynamic>>()
                {
                    new KeyValuePair<string, dynamic>("Message", "Failed to unregister a event listeners"),
                    new KeyValuePair<string, dynamic>("Event Id", msgData.EventId),
                    new KeyValuePair<string, dynamic>("Event Name", EventType.GetInstance().GetNameById(msgData.EventId)),
                    new KeyValuePair<string, dynamic>("Error", e.Message)
                };

                listener(m);
                /// it is very unexpected situation.
                /// need to figure out a way to prevent it or handle it more gracefully
            }
#pragma warning restore CA1031 // Do not catch general exception types
        }