brick-framework/GameCore/Events/EventBus.cs

using GameCore.Events.Interfaces;

namespace GameCore.Events;

public class EventBus
{
    private readonly Queue<IEvent> _eventQueue = new();
    private readonly Dictionary<Type, List<Action<IEvent>>> _subscribers = new();

    public void Subscribe<T>(Action<T> listener) where T : IEvent
    {
        var eventType = typeof(T);
        if (!_subscribers.ContainsKey(eventType)) _subscribers[eventType] = [];

        _subscribers[eventType].Add(e => listener((T)e));
    }

    public void Unsubscribe<T>(Action<T> listener) where T : IEvent
    {
        var eventType = typeof(T);
        if (!_subscribers.TryGetValue(eventType, out var listeners)) return;

        listeners.RemoveAll(e => e.Equals((Action<IEvent>)(e1 => listener((T)e1))));

        if (listeners.Count == 0) _subscribers.Remove(eventType);
    }

    public void Publish(IEvent gameEvent)
    {
        _eventQueue.Enqueue(gameEvent);
    }

    public void ProcessEvents()
    {
        while (_eventQueue.Count > 0)
        {
            var gameEvent = _eventQueue.Dequeue();
            var eventType = gameEvent.GetType();

            if (!_subscribers.TryGetValue(eventType, out var listeners)) continue;

            foreach (var listener in listeners)
                listener.Invoke(gameEvent);
        }
    }
}