import turtle
import time
import tkinter

delay = .05
#setup Screen
wn = turtle.Screen()
wn.title("Snake Game")
wn.bgcolor("green")
wn.setup(width=600, height=600)
wn.tracer(0)


#Snake

snakeHead = turtle.Turtle()
snakeHead.speed(0)
snakeHead.shape("square")
snakeHead.color("blue")
snakeHead.penup()
snakeHead.goto(0,0)
snakeHead.direction = "stop"

def changeUp():
    snakeHead.direction = "up"

def changeDown():
    snakeHead.direction = "down"

def changeRight():
    snakeHead.direction = "right"

def changeLeft():
    snakeHead.direction = "left"

def move():
    if snakeHead.direction == "up":
        y = snakeHead.ycor();
        snakeHead.sety(y + 20)

    if snakeHead.direction == "down":
        y = snakeHead.ycor();
        snakeHead.sety(y - 20)

    if snakeHead.direction == "right":
        x = snakeHead.xcor();
        snakeHead.setx(x + 20)

    if snakeHead.direction == "left":
        x = snakeHead.xcor();
        snakeHead.setx(x - 20)

wn.listen()
wn.onkeypress(changeUp(), "w")
wn.onkeypress(changeDown(), "s")
wn.onkeypress(changeRight(), "d")
wn.onkeypress(changeLeft(), "a")

while True:
    wn.update()
    move()

    time.sleep(delay)

wn.mainloop();