"""贪吃蛇"""

import random
import sys
import time
import pygame
from pygame.locals import *
from collections import deque

SCREEN_WIDTH = 600  # 屏幕宽度
SCREEN_HEIGHT = 480  # 屏幕高度
SIZE = 20    # 小方格大小
LINE_WIDTH = 1   # 网格线宽度

# 游戏区域的坐标范围
SCOPE_X = (0, SCREEN_WIDTH // SIZE - 1)
SCOPE_Y = (2, SCREEN_HEIGHT // SIZE - 1)

# 食物的分值及颜色
FOOD_STYLE_LIST = [(10, (255, 100, 100)), (20, (100, 255, 100)), (30, (100, 100, 255))]

LIGHT = (100, 100, 100)
DARK = (200, 200, 200)  # 蛇的颜色
BLACK = (0, 0, 0)   # 网格线颜色
RED = (200, 30, 30)   # 红色，GAME OVER 的字体颜色
BGCOLOR = (40, 40, 60)  # 背景色


def print_text(screen, font, x, y, text, fcolor=(255, 255, 255)):
 imgText = font.render(text, True, fcolor)
 screen.blit(imgText, (x, y))


# 初始化蛇
def init_snake():
 snake = deque()
 snake.append((2, SCOPE_Y[0]))
 snake.append((1, SCOPE_Y[0]))
 snake.append((0, SCOPE_Y[0]))
 return snake


def create_food(snake):
 food_x = random.randint(SCOPE_X[0], SCOPE_X[1])
 food_y = random.randint(SCOPE_Y[0], SCOPE_Y[1])
 while (food_x, food_y) in snake:
  # 如果食物出现在蛇身上，则重来
  food_x = random.randint(SCOPE_X[0], SCOPE_X[1])
  food_y = random.randint(SCOPE_Y[0], SCOPE_Y[1])
 return food_x, food_y


def get_food_style():
 return FOOD_STYLE_LIST[random.randint(0, 2)]


def main():
 pygame.init()
 screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
 pygame.display.set_caption('贪吃蛇')

 font1 = pygame.font.SysFont('SimHei', 24) # 得分的字体
 font2 = pygame.font.Font(None, 72) # GAME OVER 的字体
 fwidth, fheight = font2.size('GAME OVER')

 # 如果蛇正在向右移动，那么快速点击向下向左，由于程序刷新没那么快，向下事件会被向左覆盖掉，导致蛇后退，直接GAME OVER
 # b 变量就是用于防止这种情况的发生
 b = True

 # 蛇
 snake = init_snake()
 # 食物
 food = create_food(snake)
 food_style = get_food_style()
 # 方向
 pos = (1, 0)

 game_over = True
 start = False  # 是否开始，当start = True，game_over = True 时，才显示 GAME OVER
 score = 0   # 得分
 orispeed = 0.5  # 原始速度
 speed = orispeed
 last_move_time = None
 pause = False  # 暂停

 while True:
  for event in pygame.event.get():
   if event.type == QUIT:
    sys.exit()
   elif event.type == KEYDOWN:
    if event.key == K_RETURN:
     if game_over:
      start = True
      game_over = False
      b = True
      snake = init_snake()
      food = create_food(snake)
      food_style = get_food_style()
      pos = (1, 0)
      # 得分
      score = 0
      last_move_time = time.time()
    elif event.key == K_SPACE:
     if not game_over:
      pause = not pause
    elif event.key in (K_w, K_UP):
     # 这个判断是为了防止蛇向上移时按了向下键，导致直接 GAME OVER
     if b and not pos[1]:
      pos = (0, -1)
      b = False
    elif event.key in (K_s, K_DOWN):
     if b and not pos[1]:
      pos = (0, 1)
      b = False
    elif event.key in (K_a, K_LEFT):
     if b and not pos[0]:
      pos = (-1, 0)
      b = False
    elif event.key in (K_d, K_RIGHT):
     if b and not pos[0]:
      pos = (1, 0)
      b = False

  # 填充背景色
  screen.fill(BGCOLOR)
  # 画网格线 竖线
  for x in range(SIZE, SCREEN_WIDTH, SIZE):
   pygame.draw.line(screen, BLACK, (x, SCOPE_Y[0] * SIZE), (x, SCREEN_HEIGHT), LINE_WIDTH)
  # 画网格线 横线
  for y in range(SCOPE_Y[0] * SIZE, SCREEN_HEIGHT, SIZE):
   pygame.draw.line(screen, BLACK, (0, y), (SCREEN_WIDTH, y), LINE_WIDTH)

  if not game_over:
   curTime = time.time()
   if curTime - last_move_time > speed:
    if not pause:
     b = True
     last_move_time = curTime
     next_s = (snake[0][0] + pos[0], snake[0][1] + pos[1])
     if next_s == food:
      # 吃到了食物
      snake.appendleft(next_s)
      score += food_style[0]
      speed = orispeed - 0.03 * (score // 100)
      food = create_food(snake)
      food_style = get_food_style()
     else:
      if SCOPE_X[0] <= next_s[0] <= SCOPE_X[1] and SCOPE_Y[0] <= next_s[1] <= SCOPE_Y[1]         and next_s not in snake:
       snake.appendleft(next_s)
       snake.pop()
      else:
       game_over = True

  # 画食物
  if not game_over:
   # 避免 GAME OVER 的时候把 GAME OVER 的字给遮住了
   pygame.draw.rect(screen, food_style[1], (food[0] * SIZE, food[1] * SIZE, SIZE, SIZE), 0)

  # 画蛇
  for s in snake:
   pygame.draw.rect(screen, DARK, (s[0] * SIZE + LINE_WIDTH, s[1] * SIZE + LINE_WIDTH,
           SIZE - LINE_WIDTH * 2, SIZE - LINE_WIDTH * 2), 0)

  print_text(screen, font1, 30, 7, f'速度: {score//100}')
  print_text(screen, font1, 450, 7, f'得分: {score}')

  if game_over:
   if start:
    print_text(screen, font2, (SCREEN_WIDTH - fwidth) // 2, (SCREEN_HEIGHT - fheight) // 2, 'GAME OVER', RED)

  pygame.display.update()


if __name__ == '__main__':
 main()