Fix more edge cases

Toolkit.Foundation/AggerateAttribute.cs

@@ -1,7 +1,3 @@
 namespace Toolkit.Foundation;
 
-public class AggerateAttribute(Type type, object key,
-    AggerateMode mode = AggerateMode.Reset) : NotificationAttribute(type, key)
-{
-    public AggerateMode Mode => mode;
-}
+public class AggerateAttribute(Type type, object key) : NotificationAttribute(type, key);

Toolkit.Foundation/AggerateEventArgs.cs

@@ -1,31 +0,0 @@
-namespace Toolkit.Foundation;
-
-public record Aggerate
-{
-    public static AggerateEventArgs<TValue, TOptions> With<TValue, TOptions>(TOptions options) where TOptions : class
-    {
-        return new AggerateEventArgs<TValue, TOptions>(options);
-    }
-
-    public static AggerateEventArgs<TValue> With<TValue>()
-    {
-        return new AggerateEventArgs<TValue>();
-    }
-}
-
-public record AggerateEventArgs<TValue, TOptions>(TOptions? Options = null) :
-    IAggerate
-    where TOptions : class
-{
-    public object? Key { get; init; }
-
-    public AggerateMode Mode { get; init; }
-}
-
-public record AggerateEventArgs<TValue> :
-    IAggerate
-{
-    public object? Key { get; init; }
-
-    public AggerateMode Mode { get; init; }
-}

Toolkit.Foundation/AggerateMode.cs

@@ -1,7 +0,0 @@
-namespace Toolkit.Foundation;
-
-public enum AggerateMode
-{
-    Append,
-    Reset
-}

Toolkit.Foundation/Aggregate.cs

@@ -0,0 +1,10 @@
+namespace Toolkit.Foundation;
+
+public record Aggregate
+{
+    public static AggregateEventArgs<TValue, TOptions> As<TValue, TOptions>(TOptions options)
+        where TOptions : class => new(options);
+
+    public static AggerateEventArgs<TValue> As<TValue>() =>
+        new AggerateEventArgs<TValue>();
+}

Toolkit.Foundation/AggregateEventArgs.cs

@@ -0,0 +1,8 @@
+namespace Toolkit.Foundation;
+
+public record AggregateEventArgs<TValue, TOptions>(TOptions? Options = null) :
+    IAggregate
+    where TOptions : class;
+
+public record AggerateEventArgs<TValue> :
+    IAggregate;

Toolkit.Foundation/AggregateExpression.cs

@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public record AggregateExpression(IAggregate Value, object? Key = null);

Toolkit.Foundation/HandlerProvider.cs

@@ -6,6 +6,7 @@ public class HandlerProvider(SubscriptionCollection subscriptions) :
     public IEnumerable<object?> Get(Type type,
         object? key = null)
     {
+        var d = subscriptions;
         string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{type}";
         if (subscriptions.TryGetValue(subscriptionKey, out List<WeakReference>? subscribers))
         {

Toolkit.Foundation/IAggerate.cs

@@ -1,6 +0,0 @@
-namespace Toolkit.Foundation;
-
-public interface IAggerate
-{
-    object? Key { get; init; }
-}

Toolkit.Foundation/IAggregate.cs

@@ -0,0 +1,3 @@
+namespace Toolkit.Foundation;
+
+public interface IAggregate;

Toolkit.Foundation/IPublisher.cs

@@ -2,14 +2,14 @@
 
 public interface IPublisher
 {
-    void Publish<TMessage>(object key)
+    void Publish<TMessage>(object? key = null)
         where TMessage : new();
 
     void Publish<TMessage>(TMessage message)
         where TMessage : notnull;
 
     void Publish<TMessage>(TMessage message,
-        object key)
+        object? key = null)
         where TMessage : notnull;
 
     void Publish(object message,
@@ -22,9 +22,9 @@ public interface IPublisher
     void Publish(object message);
 
     void PublishUI<TMessage>(TMessage message,
-        object key) where TMessage : notnull;
+        object? key = null) where TMessage : notnull;
 
-    void PublishUI<TMessage>(object key)
+    void PublishUI<TMessage>(object? key = null)
         where TMessage : new();
 
     void PublishUI<TMessage>(TMessage message)

Toolkit.Foundation/ObservableCollection.cs

@@ -192,20 +192,20 @@ public partial class ObservableCollection<TItem> :
         }
     }
 
-    public void BeginAggregation()
+    public void Fetch(bool reset = false)
     {
-        if (this.GetAttribute<AggerateAttribute>() is AggerateAttribute attribute)
+        if (reset)
         {
-            if (attribute.Mode == AggerateMode.Reset)
-            {
-                Clear();
-            }
-
-            object? key = this.GetPropertyValue(() => attribute.Key) is { } value ? value : attribute.Key;
-            Publisher.PublishUI(OnAggerate(key));
+            Clear();
         }
+
+        AggregateExpression expression = CreateAggregateExpression();
+        Publisher.PublishUI(expression.Value, expression.Key);
     }
 
+    protected virtual IAggregate OnAggerate() =>
+        new AggerateEventArgs<TItem>();
+
     public void Clear()
     {
         clearing = true;
@@ -389,7 +389,7 @@ public partial class ObservableCollection<TItem> :
         }
 
         Initialized = true;
-        BeginAggregation();
+        Fetch();
 
         return Task.CompletedTask;
     }
@@ -565,8 +565,11 @@ public partial class ObservableCollection<TItem> :
         collection.Insert(index > Count ? Count : index, item);
     }
 
-    protected virtual IAggerate OnAggerate(object? key) =>
-        new AggerateEventArgs<TItem>() with { Key = key };
+    protected virtual AggregateExpression CreateAggregateExpression() => 
+        new AggregateExpression(new AggerateEventArgs<TItem>());
+
+    protected virtual object? CreateAggregationKey() =>
+        default;
 
     protected virtual void RemoveItem(int index) =>
         collection.RemoveAt(index);

Toolkit.Foundation/Publisher.cs

@@ -9,7 +9,7 @@ public class Publisher(IHandlerProvider handlerProvider,
     IDispatcher dispatcher) :
     IPublisher
 {
-    public void Publish<TMessage>(object key)
+    public void Publish<TMessage>(object? key = null)
         where TMessage : new() =>
             Publish(serviceFactory.Create<TMessage>() ?? new TMessage(), async args => await args(), key);
 
@@ -17,7 +17,8 @@ public class Publisher(IHandlerProvider handlerProvider,
         where TMessage : notnull =>
             Publish(message, async args => await args(), null);
 
-    public void Publish<TMessage>(TMessage message, object key)
+    public void Publish<TMessage>(TMessage message,
+        object? key = null)
         where TMessage : notnull =>
             Publish(message, async args => await args(), key);
 
@@ -60,7 +61,7 @@ public class Publisher(IHandlerProvider handlerProvider,
         where TMessage : new() =>
             Publish(new TMessage(), async args => await args(), null);
 
-    public void PublishUI<TMessage>(object key)
+    public void PublishUI<TMessage>(object? key = null)
         where TMessage : new() =>
             Publish(new TMessage(), args => dispatcher.Invoke(async () => await args()), key);
 
@@ -69,7 +70,7 @@ public class Publisher(IHandlerProvider handlerProvider,
             Publish(message, args => dispatcher.Invoke(async () => await args()), null);
 
     public void PublishUI<TMessage>(TMessage message,
-        object key)
+        object? key = null)
         where TMessage : notnull =>
             Publish(message, args => dispatcher.Invoke(async () => await args()), key);
 

Toolkit.Foundation/Subscription.cs

@@ -10,21 +10,37 @@ public class Subscription(SubscriptionCollection subscriptions,
     {
         Type handlerType = subscriber.GetType();
 
-        IDictionary<Type, object> keys = GetKeysFromHandler(subscriber);
+        IDictionary<Type, List<object>> subscribers = GetSubscriptionKeys(subscriber);
         foreach (Type interfaceType in GetHandlerInterfaces(handlerType))
         {
             if (interfaceType.GetGenericArguments().FirstOrDefault() is Type argumentType)
             {
-                keys.TryGetValue(argumentType, out object? key);
-
-                string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{argumentType}";
-                subscriptions.AddOrUpdate(subscriptionKey, _ => new List<WeakReference> { new(subscriber) }, (_, collection) =>
+                subscribers.TryGetValue(argumentType, out List<object>? keys);
+                if (keys is not null)
                 {
-                    collection.Add(new WeakReference(subscriber));
-                    return collection;
-                });
+                    foreach (object key in keys)
+                    {
+                        string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{argumentType}";
+                        subscriptions.AddOrUpdate(subscriptionKey, _ => new List<WeakReference> { new(subscriber) }, (_, collection) =>
+                        {
+                            collection.Add(new WeakReference(subscriber));
+                            return collection;
+                        });
 
-                disposer.Add(subscriber, Disposable.Create(() => RemoveSubscriber(subscriber, subscriptionKey)));
+                        disposer.Add(subscriber, Disposable.Create(() => RemoveSubscriber(subscriber, subscriptionKey)));
+                    }
+                }
+                else
+                {
+                    string subscriptionKey = $"{argumentType}";
+                    subscriptions.AddOrUpdate(subscriptionKey, _ => new List<WeakReference> { new(subscriber) }, (_, collection) =>
+                    {
+                        collection.Add(new WeakReference(subscriber));
+                        return collection;
+                    });
+
+                    disposer.Add(subscriber, Disposable.Create(() => RemoveSubscriber(subscriber, subscriptionKey)));
+                }
             }
         }
     }
@@ -32,21 +48,40 @@ public class Subscription(SubscriptionCollection subscriptions,
     public void Remove(object subscriber)
     {
         Type handlerType = subscriber.GetType();
-        IDictionary<Type, object> keys = GetKeysFromHandler(subscriber);
+        IDictionary<Type, List<object>> subscribers = GetSubscriptionKeys(subscriber);
         foreach (Type interfaceType in GetHandlerInterfaces(handlerType))
         {
             if (interfaceType.GetGenericArguments().FirstOrDefault() is Type argumentType)
             {
-                keys.TryGetValue(argumentType, out object? key);
-
-                string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{argumentType}";
-                if (subscriptions.TryGetValue(subscriptionKey, out List<WeakReference>? subscribers))
+                subscribers.TryGetValue(argumentType, out List<object>? keys);
+                if (keys is not null)
                 {
-                    for (int i = subscribers.Count - 1; i >= 0; i--)
+                    foreach (object key in keys)
                     {
-                        if (!subscribers[i].IsAlive || subscribers[i].Target == subscriber)
+                        string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{argumentType}";
+                        if (subscriptions.TryGetValue(subscriptionKey, out List<WeakReference>? existing))
                         {
-                            subscribers.RemoveAt(i);
+                            for (int i = existing.Count - 1; i >= 0; i--)
+                            {
+                                if (!existing[i].IsAlive || existing[i].Target == subscriber)
+                                {
+                                    existing.RemoveAt(i);
+                                }
+                            }
+                        }
+                    }
+                }
+                else
+                {
+                    string subscriptionKey = $"{argumentType}";
+                    if (subscriptions.TryGetValue(subscriptionKey, out List<WeakReference>? existing))
+                    {
+                        for (int i = existing.Count - 1; i >= 0; i--)
+                        {
+                            if (!existing[i].IsAlive || existing[i].Target == subscriber)
+                            {
+                                existing.RemoveAt(i);
+                            }
                         }
                     }
                 }
@@ -74,23 +109,23 @@ public class Subscription(SubscriptionCollection subscriptions,
         }
     }
 
-    //private object? GetKeyFromHandler(object handler) =>
-    //    handler.GetAttribute<NotificationAttribute>() is NotificationAttribute attribute
-    //        ? handler.GetPropertyValue(() => attribute.Key) is { } value ? value : attribute.Key : null;
-
-    private IDictionary<Type, object> GetKeysFromHandler(object handler)
+    private IDictionary<Type, List<object>> GetSubscriptionKeys(object subscriber)
     {
-        Dictionary<Type, object> keys = [];
-
-        foreach (NotificationAttribute attribute in handler.GetAttributes<NotificationAttribute>())
+        Dictionary<Type, List<object>> keys = [];
+        foreach (NotificationAttribute attribute in subscriber.GetAttributes<NotificationAttribute>())
         {
-            keys.Add(attribute.Type, attribute.Key);
+            if (!keys.TryGetValue(attribute.Type, out List<object>? value))
+            {
+                value = ([]);
+                keys[attribute.Type] = value;
+            }
+
+            value.Add(attribute.Key);
         }
 
         return keys;
     }
 
-
     private IEnumerable<Type> GetHandlerInterfaces(Type handlerType) =>
         handlerType.GetInterfaces().Where(interfaceType =>
         {