duck

using UnityEngine;
using System.Collections.Generic;

public class EventManager {

    private static Dictionary<Events, List<IEventListener>> listeners = new Dictionary<Events, List<IEventListener>>();

    // add listener to specified event
    public static void AddListener(IEventListener obj, Events eventKey)
    {
        if (!listeners.ContainsKey(eventKey))
        {
            listeners.Add(eventKey, new List<IEventListener>());
        }
        listeners[eventKey].Add(obj);
    }


    // remove listener from specified event
    public static void RemoveListener(IEventListener obj, Events eventKey)
    {
        List<IEventListener> listenerObjects = listeners[eventKey];
        if (listeners != null)
        {
            if (listenerObjects.Contains(obj))
            {
                listenerObjects.Remove(obj);
            }
        }
    }

    // remove listener from all events
    public static void RemoveListener(IEventListener obj)
    {
        foreach (KeyValuePair<Events, List<IEventListener>> entry in listeners)
        {
            RemoveListener(obj, entry.Key);
        }
    }

    // send event (with no data obj)
    public static void Send(Events eventKey)
    {
        Send(eventKey, null);
    }

    // send event
    public static void Send(Events eventKey, object data)
    {
        foreach (IEventListener obj in listeners[eventKey])
        {
            obj.Event(eventKey, data);
        }
    }
}

public interface IEventListener {
    void Event(Events eventKey, object data);
}