import pygame,random
pygame.init()
display_width = 800
display_height = 600
black = (0,0,0)
white = (255,255,255)
red = (255,0,0)
gameDisplay = pygame.display.set_mode((display_width,display_height))
pygame.display.set_caption('Snake')
clock = pygame.time.Clock()
snakeIMG = pygame.image.load('snake.png')
appleIMG = pygame.image.load('apple.png')
bodyIMG = pygame.image.load('body.png')
x = display_width * 0.5
y = display_height * 0.5
body_x = [x]
body_y = [y]
body_len = 0
apple_x =20 * random.randint(0,39)
apple_y =20 * random.randint(0,29)
directions = {"Left":0,"Up":1,"Right":2,"Down":3}
direction =directions["Right"]
end = False
def snake(x,y,body_x,body_y):
    gameDisplay.blit(snakeIMG, (x,y))
    for i in range(1,len(body_x)):
        gameDisplay.blit(bodyIMG, (body_x[i],body_y[i]))
def apple(x,y):
    gameDisplay.blit(appleIMG, (x,y))
def checking(x,y,apple_x,apple_y):
    if x == apple_x and y == apple_y:
        return True
    else:
        return False
def end_of_game(x,y):
    if x >= display_width or x < 0 or y >= display_height or y < 0:
        print(x,y)
        return True
    else:
        return False
def size_increasing(x,y,direction,body_x,body_y):
    if direction == 0:
        body_x.append(x+20)
        body_y.append(y)
    elif direction == 1:
        body_x.append(x)
        body_y.append(y+20)
    elif direction == 2:
        body_x.append(x-20)
        body_y.append(y)
    elif direction == 3:
        body_x.append(x)
        body_y.append(y-20)


while not end_of_game(x,y):
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            end = True
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT and direction != directions["Right"]:
                direction = directions["Left"]
            elif event.key == pygame.K_RIGHT and direction != directions["Left"]:
                direction = directions["Right"]
            elif event.key == pygame.K_UP and direction != directions["Down"]:
                direction = directions["Up"]
            elif event.key == pygame.K_DOWN and direction != directions["Up"]:
                direction = directions["Down"]
    if direction == directions["Right"]:
        x=x+20
        for i in range(len(body_x)):
            body_x[i]+=20
    elif direction == directions["Left"]:
        x=x-20
        for i in range(len(body_x)):
            body_x[i]-=20
    elif direction == directions["Up"]:
        y=y-20
        for i in range(len(body_y)):
            body_y[i]-=20
    elif direction == directions["Down"]:
        y=y+20
        for i in range(len(body_y)):
            body_y[i]+=20

    gameDisplay.fill(white)
    if  checking(x,y,apple_x,apple_y):
        apple_x =20 * random.randint(0,39)
        apple_y =20 * random.randint(0,29)
        size_increasing(x,y,direction,body_x,body_y)
        apple(apple_x,apple_y)
    else:
        apple(apple_x,apple_y)
    snake(x,y,body_x,body_y)
    pygame.display.update()
    clock.tick(15)

pygame.quit()
quit()