# 导入必要的库
import pygame
import random

# 初始化pygame
pygame.init()

# 定义颜色
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

# 设置屏幕大小
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

# 创建屏幕
screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
pygame.display.set_caption("贪吃蛇")

# 定义蛇的初始位置和大小
snake_block_size = 10
snake_speed = 15
snake_list = []
snake_length = 1
snake_x = SCREEN_WIDTH / 2
snake_y = SCREEN_HEIGHT / 2

# 定义食物的初始位置和大小
food_block_size = 10
food_x = round(random.randrange(0, SCREEN_WIDTH - food_block_size) / 10.0) * 10.0
food_y = round(random.randrange(0, SCREEN_HEIGHT - food_block_size) / 10.0) * 10.0

# 定义字体
font_style = pygame.font.SysFont(None, 50)

# 定义分数
score = 0

# 定义游戏结束函数
def game_over():
    message = font_style.render("游戏结束", True, RED)
    screen.blit(message, [SCREEN_WIDTH / 3, SCREEN_HEIGHT / 3])
    pygame.display.update()
    pygame.time.delay(2000)

# 游戏循环
game_over_flag = False
while not game_over_flag:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            game_over_flag = True

        # 控制蛇的移动
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_LEFT:
                snake_x_change = -snake_block_size
                snake_y_change = 0
            elif event.key == pygame.K_RIGHT:
                snake_x_change = snake_block_size
                snake_y_change = 0
            elif event.key == pygame.K_UP:
                snake_y_change = -snake_block_size
                snake_x_change = 0
            elif event.key == pygame.K_DOWN:
                snake_y_change = snake_block_size
                snake_x_change = 0

    # 控制蛇的移动
    snake_x += snake_x_change
    snake_y += snake_y_change

    # 判断蛇是否吃到食物
    if snake_x == food_x and snake_y == food_y:
        food_x = round(random.randrange(0, SCREEN_WIDTH - food_block_size) / 10.0) * 10.0
        food_y = round(random.randrange(0, SCREEN_HEIGHT - food_block_size) / 10.0) * 10.0
        snake_length += 1
        score += 10

    # 绘制食物
    pygame.draw.rect(screen, GREEN, [food_x, food_y, food_block_size, food_block_size])

    # 绘制蛇
    snake_head = []
    snake_head.append(snake_x)
    snake_head.append(snake_y)
    snake_list.append(snake_head)
    if len(snake_list) > snake_length:
        del snake_list[0]

    for x in snake_list[:-1]:
        if x == snake_head:
            game_over_flag = True

    for x in snake_list:
        pygame.draw.rect(screen, BLUE, [x[0], x[1], snake_block_size, snake_block_size])

    # 绘制分数
    score_message = font_style.render("分数: " + str(score), True, BLACK)
    screen.blit(score_message, [0, 0])

    # 更新屏幕
    pygame.display.update()

    # 判断蛇是否撞墙
    if snake_x >= SCREEN_WIDTH or snake_x < 0 or snake_y >= SCREEN_HEIGHT or snake_y < 0:
        game_over_flag = True

    # 控制游戏速度
    pygame.time.delay(snake_speed)

# 结束pygame
pygame.quit()