package
{
    import flash.display.MovieClip;
    import flash.events.KeyboardEvent;
    import flash.ui.Keyboard;
    import flash.events.Event;

    public class Main extends MovieClip
    {
        var vx:int;
        var vy:int;
        var rightInnerBoundary:uint;
        var leftInnerBoundary:uint;
        var topInnerBoundary:uint;
        var bottomInnerBoundary:uint;

        public function Main()
        {
            init();
        }
        function init():void
        {
            vx = 0;
            vy = 0;

            rightInnerBoundary = (stage.stageWidth / 2) + (stage.stageWidth / 4);
            leftInnerBoundary = (stage.stageWidth / 2) - (stage.stageWidth / 4);
            topInnerBoundary = (stage.stageHeight / 2) - (stage.stageHeight / 4);
            bottomInnerBoundary = (stage.stageHeight / 2) + (stage.stageHeight / 4);

            stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyPressed);
            stage.addEventListener(KeyboardEvent.KEY_UP, onKeyNotPressed);
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
        }
        function onKeyPressed(event:KeyboardEvent):void
        {
            if (event.keyCode == Keyboard.LEFT)
            {
                vx = -10;
            }
            else if (event.keyCode == Keyboard.RIGHT)
            {
                vx = 10;
            }
            else if (event.keyCode == Keyboard.UP)
            {
                vy = -10;
            }
            else if (event.keyCode == Keyboard.DOWN)
            {
                vy = 10;
            }
        }
        function onKeyNotPressed(event:KeyboardEvent):void
        {
            if (event.keyCode == Keyboard.LEFT || event.keyCode == Keyboard.RIGHT)
            {
                vx = 0;
            }
            else if (event.keyCode == Keyboard.DOWN || event.keyCode == Keyboard.UP)
            {
                vy = 0;
            }
        }
        function onEnterFrame(event:Event):void
        {
            var playerHalfWidth:uint = player.width / 2;
            var playerHalfHeight:uint = player.height / 2;
            var backgroundHalfWidth:uint = background.width / 2;
            var backgroundHalfHeight:uint = background.height / 2;

            player.x += vx;
            player.y += vy;

            if (player.x - playerHalfWidth < leftInnerBoundary)
            {
                player.x = leftInnerBoundary + playerHalfWidth;
                background.x -= vx;
            }
            else if (player.x + playerHalfWidth > rightInnerBoundary)
            {
                player.x = rightInnerBoundary - playerHalfWidth;
                background.x -= vx;
            }
            if (player.y - playerHalfHeight < topInnerBoundary)
            {
                player.y = topInnerBoundary + playerHalfHeight;
                background.y -= vy;
            }
            else if (player.y + playerHalfHeight > bottomInnerBoundary)
            {
                player.y = bottomInnerBoundary - playerHalfHeight;
                background.y -= vy;
            }


        if (background.x + backgroundHalfWidth < stage.stageWidth)
        {
            background.x = stage.stageWidth - backgroundHalfWidth;
        }
        else if (background.x - backgroundHalfWidth > 0)
        {
            background.x = 0 + backgroundHalfWidth;
        }
        if (background.y - backgroundHalfHeight > 0)
        {
            background.y = 0 + backgroundHalfHeight;
        }
        else if (background.y + backgroundHalfHeight < stage.stageHeight)
        {
            background.y = stage.stageHeight - backgroundHalfHeight;
        }

        }
    }
}