Unity C# Event System

using System;
using System.Collections.Generic;
using UnityEngine;

public class EventDispatcher : ScriptBase
{
    Dictionary<EventId, EventDelegate> events = new Dictionary<EventId, EventDelegate>();
    Dictionary<System.Delegate, EventDelegate> internalLookup = new Dictionary<Delegate, EventDelegate>();

    public void RegisterCallback<T>(EventId id, EventDelegate<T> callback) where T : EventArgs
    {
        EventDelegate internalDelegate = (e) =>
            {
                var convert = (T)e;
                callback(convert);
            };
        internalLookup[callback] = internalDelegate;

        EventDelegate handler;
        if (events.TryGetValue(id, out handler))
        {
            events[id] = handler += internalDelegate;
        }
        else
        {
            this.events[id] = internalDelegate;
        }
    }
    public void DeregisterCallback<T>(EventId id, EventDelegate<T> callback) where T : EventArgs
    {
        EventDelegate internalDelegate;
        if (internalLookup.TryGetValue(callback, out internalDelegate))
        {
            EventDelegate containingDelegate;
            if (events.TryGetValue(id, out containingDelegate))
            {
                containingDelegate -= internalDelegate;
                if (containingDelegate == null)
                {
                    events.Remove(id);
                }
                else
                {
                    events[id] = containingDelegate;
                }
            }
            internalLookup.Remove(callback);
        }
    }
    public void RaiseEvent<T>(EventId id, T eventArgs, bool needsListener = true) where T : EventArgs
    {
        EventDelegate del;
        if (events.TryGetValue(id, out del))
        {
            del.Invoke(eventArgs);
        }
        else if (needsListener)
        {
            Debug.LogWarning("Trying to raise an event with ID <" + id.ToString() + "> with no listeners on " + this.gameObject.name);
        }
    }
}

public delegate void EventDelegate<T>(T e) where T : EventArgs;
public delegate void EventDelegate(EventArgs e);

public enum EventId
{
    Damaged,
    Died,
    AbilityCast,
    Healed,
//  Etc.
}