var moveDelay : float = 0.5;
var gridSize = 1;
private var x = 0;
private var y = 0;

private var moveX = 1;
private var moveY = 0;

private var allowChangeDirection = true;
 private var bodyPieceNum = 0;

var snakeBody : ArrayList;
var body : Transform;
var head : Transform;

function Start() {
    snakeBody = new ArrayList();
    bodies = Instantiate(body,head.transform.position,head.transform.rotation);
    bodies = Instantiate(body,head.transform.position,head.transform.rotation);
    snakeBody.Add(bodies);
    snakeBody.Add(bodies);
    Move();
}

function Move() {

    while (true) {
        yield WaitForSeconds(moveDelay);

        // count the next body piece number (wrapping to zero):
        bodyPieceNum++;
        bodyPieceNum = (bodyPieceNum % snakeBody.Count);

        // place the next 'body piece' at the old head position
        snakeBody[bodyPieceNum].position = transform.position;

        // code here is executed once per 'move delay'.

        x += moveX;
        y += moveY;

        transform.position = Vector3 ( x * gridSize, 0, y * gridSize);

        // now the snake has moved a step, we can allow the user to make
        // another change in direction:
        allowChangeDirection = true;

    }
}

function Update() {

    if(Input.GetKeyDown(KeyCode.D) && moveY != -1 && allowChangeDirection){
        moveX = 0;
        moveY = 1;
        allowChangeDirection = false;
    }

    if(Input.GetKeyDown(KeyCode.A) && moveY != 1 && allowChangeDirection){
        moveX = 0;
        moveY = -1;
        allowChangeDirection = false;
    }

    if(Input.GetKeyDown(KeyCode.S) && moveX != -1 && allowChangeDirection){
        moveX = 1;
        moveY = 0;
        allowChangeDirection = false;
    }

    if(Input.GetKeyDown(KeyCode.W) && moveX != 1 && allowChangeDirection){
        moveX = -1;
        moveY = 0;
        allowChangeDirection = false;
    }

}