snake game

import pygame
import random
import os
pygame.init()
pygame.mixer.init()

#colors
white=(255,255,255)
red=(255,0,0)
black=(0,0,0)

#game window
screen_w=500
screen_h=500
gamewindow=pygame.display.set_mode((screen_w,screen_h))
pygame.display.set_caption("snake game")
clock=pygame.time.Clock()

#background
image=pygame.image.load("background.jpg")
image=pygame.transform.scale(image,(screen_w,screen_h)).convert_alpha()

#text on screen
font=pygame.font.SysFont(None,30)
def screentext(text,color,x,y):
    textonscreen=font.render(text,True,color)
    gamewindow.blit(textonscreen,[x,y])

#snake length increment(plotting snake)
def plotsnake(gamewindow,color,snk_list,snake_size):
    for x,y in snk_list:
        pygame.draw.rect(gamewindow, color, [x, y, snake_size, snake_size])

def welcome():
    pygame.mixer.music.load("snakeGameback.mp3")
    pygame.mixer.music.set_volume(0.7)
    pygame.mixer.music.play()
    fps=30
    game_e = False
    while not game_e:
        gamewindow.fill(white)
        screentext("Welcome To Snake Game", black, 130, 150)
        screentext("press Enter To Start The Game", black,110,180)
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                game_e=True
            if event.type == pygame.KEYDOWN:
                if event.key==pygame.K_RETURN:
                    pygame.mixer.music.load("snakeGameback.mp3")
                    pygame.mixer.music.set_volume(0.7)
                    pygame.mixer.music.pause()
                    gameloop()
        pygame.display.flip()
        clock.tick(fps)

#game loop
def gameloop():
    # game specific variables
    game_o = False
    game_e = False
    snake_x = 1
    snake_y = 40
    velocity_x = 0
    velocity_y = 0
    snake_size = 15
    init_velocity = 5
    food_x = random.randint(10, screen_w / 2)
    food_y = random.randint(10, screen_h / 2)
    food_size = 15
    score = 0
    fps = 30
    snk_list = []
    snk_length = 0
    if (not os.path.exists("highscore.txt")):
        with open("highscore.txt", "w") as f:
            f.write("0")
    with open("highscore.txt", "r") as f:
        highscore = f.read()

    gamewindow.fill(white)
    while not game_e:

        if game_o==True:
            with open("highscore.txt", "w") as f:
                f.write(str(highscore))
            gamewindow.fill(white)
            screentext("Game Over!press enter to restart", red, 90,190)
            screentext("your score: " + str(score), black, 180, 220)
            for event in pygame.event.get():
                if event.type==pygame.QUIT:
                    game_e = True
                if event.type==pygame.KEYDOWN:
                    if event.key==pygame.K_RETURN:
                        welcome()
        else:
            for event in pygame.event.get():
                if event.type==pygame.QUIT:
                    game_e = True
                if event.type==pygame.KEYDOWN:
                    if event.key==pygame.K_RIGHT:
                        velocity_x=init_velocity
                        velocity_y=0
                    if event.key==pygame.K_LEFT:
                        velocity_x = -init_velocity
                        velocity_y=0
                    if event.key==pygame.K_UP:
                        velocity_y = -init_velocity
                        velocity_x = 0
                    if event.key==pygame.K_DOWN:
                        velocity_y = init_velocity
                        velocity_x = 0
            if abs(snake_x-food_x)<6 and abs(snake_y-food_y)<6:
                pygame.mixer.music.load("snakeeat.mp3")
                pygame.mixer.music.set_volume(0.7)
                pygame.mixer.music.play()
                score+=10
                food_x = random.randint(10, screen_w/2)
                food_y = random.randint(10, screen_h/2)
                snk_length+=5

                if score>int(highscore):
                    highscore=score

            snake_x+=velocity_x
            snake_y+=velocity_y

            head=[]
            head.append(snake_x)
            head.append(snake_y)
            snk_list.append(head)
            if len(snk_list)>snk_length:
                del snk_list[0]

            #game over
            if snake_x>screen_w or snake_x<0 or snake_y>screen_h or snake_y<0:
                game_o=True
            if head in snk_list[:-1]:
                game_o=True

            gamewindow.fill(black)
            gamewindow.blit(image, (0, 0))
            pygame.draw.rect(gamewindow,black,[snake_x,snake_y,snake_size,snake_size])
            pygame.draw.rect(gamewindow,red,[food_x,food_y,food_size,food_size])
            screentext("score:"+ str(score)+ "  Highscore:"+str(highscore),red,5,5)
            plotsnake(gamewindow, black, snk_list, snake_size)

        pygame.display.update()
        clock.tick(fps)

    pygame.quit()
    exit()

welcome()