class IEventHandler
{
    Map<String, List<Function>> _events;

    register(String event)
    {
        _events[event.toLowerCase()] = [];
    }

    IEventHandler()
    {
        _events = {};
    }

    emitArgs(String event, List arguments)
    {
        event = event.toLowerCase();
        if (_events.containsKey(event))
            for(var i = 0; i < _events[event].length; i++)
                if (Function.apply(_events[event][i], arguments) != null)
                    return true;

        return false;
    }

    on(String event, Function callback)
    {
        event = event.toLowerCase();
        // add
        if (!_events.containsKey(event))
            register(event);

        _events[event].add(callback);
        return this;
    }

    off(event, callback)
    {
        event = event.toString();
        if (_events.containsKey(event))
        {
            if (callback != null)
              _events[event].remove(callback);
            else
                this._events[event] = [];
        }
    }
}