package org.tamina.events;

import haxe.ds.StringMap;

/**
* The EventDispatcher class is the base class for all classes that dispatch events. The EventDispatcher class allows any object on the display list to be an event target and as such, to use the methods of the EventDispatcher class.
* <br>
* In general, the easiest way for a user-defined class to gain event dispatching capabilities is to extend EventDispatcher. If this is impossible (that is, if the class is already extending another class), you can instead create an EventDispatcher member, and write simple hooks to route calls into the aggregated EventDispatcher.
*
*      class ExternalEventBus extends EventDispatcher<SakuraEventType> {
*
*       public static var instance(get, null):ExternalEventBus;
*       private static var _instance:ExternalEventBus;
*
*       private function new() {
*           super();
*       }
*
*       private static function get_instance():ExternalEventBus {
*           if (_instance == null) {
*              _instance = new ExternalEventBus();
*           }
*           return _instance;
*       }
*
*       public function send(event:Event<SakuraEventType>):Void {
*           if (_eventsCallback.exists(event.type)) {
*             dispatchEvent(event);
*           }
*       }
*
*     }
* @class EventDispatcher[T]
* @module Tamina
*/
class EventDispatcher<T:String> {


    private var _eventsCallback:StringMap<Array<Event<T> -> Void>>;

/**
    * @constructor
    * @method new
    */

    public function new( ) {

        _eventsCallback = new StringMap<Array<Event<T> -> Void>>();
    }

/**
	 * This method registers the specified listener on the target it's called on
	 * @method addEventListener
	 * @param	type {T} A string representing the event type to listen for.
	 * @param listener {Event}<T> -> Void The function that's called when an event of the specified type occurs.
	 * @example
	 *      _editor.addEventListener(SakuraEventType.CUSTOMER_DESIGN_ADDED, customerDesignAddedHandler);
	 *      private function customerDesignAddedHandler(evt:SakuraEvent):Void {
	 *      }
	 */
    public function addEventListener( type:T, listener:Event<T> -> Void ):Void {
        if ( !_eventsCallback.exists(type) ) {
            _eventsCallback.set(type, new Array<Event<T> -> Void>());
        }
        _eventsCallback.get(type).push(listener);
    }

/**
	 * Removes the event listener previously registered with addEventListener().
	 * @method removeEventListener
	 * @param	type {T} A string representing the event type to remove.
	 * @param listener {Event}<T> -> Void The EventListener function to remove from the event target.
	 * @example
	 *      _editor.removeEventListener(SakuraEventType.CUSTOMER_DESIGN_ADDED, customerDesignAddedHandler);
	 */
    public function removeEventListener( type:T, listener:Event<T> -> Void ):Void {
        if ( _eventsCallback.exists(type) ) {
            var events = _eventsCallback.get(type);
            events.remove(listener);
        }
    }

/**
	 * Removes all listeners previously registered with addEventListener() on a specific type.
	 * @method removeAllEventListeners
	 * @param	type {T} A string representing the event type to remove.
	 * @example
	 *      _editor.removeAllEventListeners(SakuraEventType.CUSTOMER_DESIGN_ADDED);
	 */
    public function removeAllEventListeners( type:T ):Void {
        if ( _eventsCallback.exists(type) ) {
            _eventsCallback.remove(type);
        }
    }

/**
	 * Dispatch an event to this EventDispatcher.
	 * @method dispatchEvent
	 * @param	event {Event}<T> event is the Event object to be dispatched.
	 * @example
	 *      this.dispatchEvent(new SakuraEvent(SakuraEventType.PROGRESS, new Progress(progress.loaded, progress.total))) ;
	 */
    public function dispatchEvent( event:Event<T> ):Void {
        if ( _eventsCallback.exists(event.type) ) {
            var events = _eventsCallback.get(event.type).slice(0);
            for ( i in 0...events.length ) {
                if (_eventsCallback.get(event.type).indexOf(events[i]) > -1) {
                    events[i](event);
                }
            }
        }
    }
}