import pygame,sys,time,random

from pygame.locals import *

# 定义颜色变量

redColour = pygame.Color(255,0,0)

blackColour = pygame.Color(0,0,0)

whiteColour = pygame.Color(255,255,255)

greyColour = pygame.Color(150,150,150)

# 定义gameOver函数

def gameOver(playSurface):

    gameOverFont = pygame.font.Font('arial.ttf',72)

    gameOverSurf = gameOverFont.render('Game Over', True, greyColour)

    gameOverRect = gameOverSurf.get_rect()

    gameOverRect.midtop = (320, 10)

    playSurface.blit(gameOverSurf, gameOverRect)

    pygame.display.flip()

    time.sleep(5)

    pygame.quit()

    sys.exit()

# 定义main函数

def main():

    # 初始化pygame

    pygame.init()

    fpsClock = pygame.time.Clock()

    # 创建pygame显示层

    playSurface = pygame.display.set_mode((640,480))

    pygame.display.set_caption('Raspberry Snake')

    # 初始化变量

    snakePosition = [100,100]

    snakeSegments = [[100,100],[80,100],[60,100]]

    raspberryPosition = [300,300]

    raspberrySpawned = 1

    direction = 'right'

    changeDirection = direction

    while True:

        # 检测例如按键等pygame事件

        for event in pygame.event.get():

            if event.type == QUIT:

                pygame.quit()

                sys.exit()

            elif event.type == KEYDOWN:

                # 判断键盘事件

                if event.key == K_RIGHT or event.key == ord('d'):

                    changeDirection = 'right'

                if event.key == K_LEFT or event.key == ord('a'):

                    changeDirection = 'left'

                if event.key == K_UP or event.key == ord('w'):

                    changeDirection = 'up'

                if event.key == K_DOWN or event.key == ord('s'):

                    changeDirection = 'down'

                if event.key == K_ESCAPE:

                    pygame.event.post(pygame.event.Event(QUIT))

        # 判断是否输入了反方向

        if changeDirection == 'right' and not direction == 'left':

            direction = changeDirection

        if changeDirection == 'left' and not direction == 'right':

            direction = changeDirection

        if changeDirection == 'up' and not direction == 'down':

            direction = changeDirection

        if changeDirection == 'down' and not direction == 'up':

            direction = changeDirection

        # 根据方向移动蛇头的坐标

        if direction == 'right':

            snakePosition[0] += 20

        if direction == 'left':

            snakePosition[0] -= 20

        if direction == 'up':

            snakePosition[1] -= 20

        if direction == 'down':

            snakePosition[1] += 20

        # 增加蛇的长度

        snakeSegments.insert(0,list(snakePosition))

        # 判断是否吃掉了树莓

        if snakePosition[0] == raspberryPosition[0] and snakePosition[1] == raspberryPosition[1]:

            raspberrySpawned = 0

        else:

            snakeSegments.pop()

        # 如果吃掉树莓，则重新生成树莓

        if raspberrySpawned == 0:

            x = random.randrange(1,32)

            y = random.randrange(1,24)

            raspberryPosition = [int(x*20),int(y*20)]

            raspberrySpawned = 1

        # 绘制pygame显示层

        playSurface.fill(blackColour)

        for position in snakeSegments:

            pygame.draw.rect(playSurface,whiteColour,Rect(position[0],position[1],20,20))

            pygame.draw.rect(playSurface,redColour,Rect(raspberryPosition[0], raspberryPosition[1],20,20))

        # 刷新pygame显示层

        pygame.display.flip()

        # 判断是否死亡

        if snakePosition[0] > 620 or snakePosition[0] < 0:

            gameOver(playSurface)

        if snakePosition[1] > 460 or snakePosition[1] < 0:

            for snakeBody in snakeSegments[1:]:

                if snakePosition[0] == snakeBody[0] and snakePosition[1] == snakeBody[1]:

                    gameOver(playSurface)

        # 控制游戏速度

        fpsClock.tick(15)

if __name__ == "__main__":

    main()