add start of mediator

MareSynchronos/Mediator/MareMediator.cs

@@ -0,0 +1,51 @@
+using MareSynchronos.Utils;
+
+namespace MareSynchronos.Mediator;
+
+public class MareMediator : IDisposable
+{
+    private record MediatorSubscriber(object Subscriber, Action<IMessage> Action);
+
+    private readonly Dictionary<Type, HashSet<MediatorSubscriber>> _subscriberDict = new();
+
+    public void Subscribe<T>(object subscriber, Action<IMessage> action) where T : IMessage
+    {
+        _subscriberDict.TryAdd(typeof(T), new HashSet<MediatorSubscriber>());
+
+        if (!_subscriberDict[typeof(T)].Add(new(subscriber, action)))
+        {
+            throw new InvalidOperationException("Already subscribed");
+        }
+    }
+
+    public void Unsubscribe<T>(object subscriber) where T : IMessage
+    {
+        if (_subscriberDict.TryGetValue(typeof(T), out var subscribers))
+        {
+            subscribers.RemoveWhere(p => p.Subscriber == subscriber);
+        }
+    }
+
+    public void Publish(IMessage message)
+    {
+        if (_subscriberDict.TryGetValue(message.GetType(), out var subscribers))
+        {
+            foreach (var subscriber in subscribers)
+            {
+                try
+                {
+                    subscriber.Action.Invoke(message);
+                }
+                catch (Exception ex)
+                {
+                    Logger.Error("Error executing " + subscriber.Action.Method, ex);
+                }
+            }
+        }
+    }
+
+    public void Dispose()
+    {
+        _subscriberDict.Clear();
+    }
+}