package FlashGame.LevelObjects
{
    import flash.events.Event;

    import mx.collections.ArrayList;
    import mx.controls.Image;

    import spark.components.Group;

    /**
     * LevelObject is the superclass for all objects which make up a level.
     * It contains logic for creating a small animation from a series of
     * images, and a local coordinate system for positioning level objects
     * correctly.
     *
     * @author Andrew Dodd <2010-11-15>
     */
    public class LevelObject extends Group
    {
        private var _mapX:uint, _mapY:uint = 0;

        private var _frames:ArrayList;
        private var _currentFrame:uint;
        private var _frameskip:uint, _currFrameskip:uint;

        /**
         * Default constructor.
         *
         * @param posX      The X position of the object, in blocks
         * @param posY      The Y position of the object, in blocks
         * @param animated  True if this is to be an animated object
         * @param frameskip The number of frames to skip on an animated object,
         *                  used to control the delay between frames - a
         *                  frameskip of 1 will skip every other frame event
         */
        public function LevelObject(posX:uint, posY:uint,
                                    animated:Boolean = false,
                                    frameskip:uint = 2)
        {
            super();
            _mapX = posX; _mapY = posY;
            updateLocalPosition();

            _frames = new ArrayList();
            _currentFrame = _currFrameskip = 0;
            _frameskip = frameskip;

            /* If this is an animated sprite then add a frame event handler */
            if(animated) {
                addEventListener(Event.ENTER_FRAME, onEnterFrame);
            }
        }

        /**
         * updateLocalPosition sets the true x and y coordinates of the object
         * based on its block coordinates
         */
        protected final function updateLocalPosition():void {
            x = _mapX * 32;
            y = _mapY * 32;
        }

        /**
         * addSource adds an image to the image array. The first image added to
         * the array is played back first, then the next, and so on.
         *
         * @param source        The image to add as a source.
         */
        protected function addSource(source:String):void {
            var img:Image = new Image();
            img.source = source;
            img.visible = true;

            addElement(img);
            _frames.addItem(img);
        }

        /**
         * Display the next frame
         */
        private function onEnterFrame(e:Event):void {
            /* If we are skipping frames, check if this is a skipped frame */
            if(_frameskip > 0) {
                _currFrameskip = (_currFrameskip + 1) % (_frameskip + 1);
            }

            /* If it is not a skipped frame, get the next frame */
            if(_currFrameskip == 0)
                _currentFrame = (_currentFrame + 1) % _frames.length;

            /* Set the correct image to be visible */
            for (var i:uint = 0; i < _frames.length; i++) {
                Image(_frames.getItemAt(i)).visible = (i == _currentFrame);
            }
        }
    }
}