wip

2024-06-12 23:04:22 +01:00
parent c8f447251e
commit b155f5c6e2
40 changed files with 262 additions and 249 deletions
@@ -0,0 +1,144 @@
+using System.Reactive.Disposables;
+
+namespace Toolkit.Foundation;
+
+public class Subscriber(SubscriptionCollection subscriptions,
+    IDisposer disposer) :
+    ISubscriber
+{
+    public void Subscribe(object subscriber)
+    {
+        Type handlerType = subscriber.GetType();
+
+        IDictionary<Type, List<object>> subscribers = GetSubscriptionKeys(subscriber);
+        foreach (Type interfaceType in GetHandlerInterfaces(handlerType))
+        {
+            if (interfaceType.GetGenericArguments().FirstOrDefault() is Type argumentType)
+            {
+                subscribers.TryGetValue(argumentType, out List<object>? keys);
+                if (keys is not null)
+                {
+                    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)));
+                    }
+                }
+                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)));
+                }
+            }
+        }
+    }
+
+    public void Unsubscribe(object subscriber)
+    {
+        Type handlerType = subscriber.GetType();
+        IDictionary<Type, List<object>> subscribers = GetSubscriptionKeys(subscriber);
+        foreach (Type interfaceType in GetHandlerInterfaces(handlerType))
+        {
+            if (interfaceType.GetGenericArguments().FirstOrDefault() is Type argumentType)
+            {
+                subscribers.TryGetValue(argumentType, out List<object>? keys);
+                if (keys is not null)
+                {
+                    foreach (object key in keys)
+                    {
+                        string subscriptionKey = $"{(key is not null ? $"{key}:" : "")}{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);
+                                }
+                            }
+                        }
+                    }
+                }
+                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);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    private void RemoveSubscriber(object subscriber,
+        string key)
+    {
+        if (subscriptions.TryGetValue(key, out List<WeakReference>? subscribers))
+        {
+            for (int i = subscribers.Count - 1; i >= 0; i--)
+            {
+                if (subscribers[i].Target == subscriber)
+                {
+                    subscribers.RemoveAt(i);
+                }
+            }
+
+            if (subscribers.Count == 0)
+            {
+                subscriptions.TryRemove(key, out _);
+            }
+        }
+    }
+
+    private IDictionary<Type, List<object>> GetSubscriptionKeys(object subscriber)
+    {
+        Dictionary<Type, List<object>> keys = [];
+        foreach (NotificationAttribute attribute in subscriber.GetAttributes<NotificationAttribute>())
+        {
+            if (!keys.TryGetValue(attribute.Type, out List<object>? value))
+            {
+                value = ([]);
+                keys[attribute.Type] = value;
+            }
+
+            if (subscriber.GetPropertyValue(() => attribute.Key) is object key)
+            {
+                value.Add(key);
+            }
+            else
+            {
+                value.Add(attribute.Key);
+            }
+        }
+
+        return keys;
+    }
+
+    private IEnumerable<Type> GetHandlerInterfaces(Type handlerType) =>
+        handlerType.GetInterfaces().Where(interfaceType =>
+        {
+            Type? definition = interfaceType.IsGenericType ? interfaceType.GetGenericTypeDefinition() : null;
+            return definition == typeof(INotificationHandler<>) ||
+                   definition == typeof(IHandler<>) ||
+                   definition == typeof(IHandler<,>);
+        });
+}