import pygame
import sys

#函数名含义：check events for mode (selecting),下同
def check_mode_events(settings):
    for event in pygame.event.get():
        # 当按关闭或者按ESC键退出游戏
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
                sys.exit()
            # 按1键选择手动模式
            elif event.key == pygame.K_1:
                settings.game_mode = 1
            # 按2键选择自动模式
            elif event.key == pygame.K_2:
                settings.game_mode = 2

 
def check_play_events(snake):
    """检测游戏过程中的按键"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
                sys.exit()
            elif event.key == pygame.K_LEFT and not snake.direction == 'right':  #防止反向移动
                snake.direction = 'left'
                break
            elif event.key == pygame.K_RIGHT and not snake.direction == 'left':
                snake.direction = 'right'
                break
            elif event.key == pygame.K_UP and not snake.direction == 'down':
                snake.direction = 'up'
                break
            elif event.key == pygame.K_DOWN and not snake.direction == 'up':
                snake.direction = 'down'
                break


def autocheck_events(ai,snake,apple,settings):
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
                sys.exit()
    if eat_apple(snake,apple):
        ai.start(snake,apple,settings)

def show_start(settings, screen):
    """模式选择界面"""
    title_Font = pygame.font.Font(settings.font_name, 80)  # 设置标题字体
    title_image = title_Font.render("贪吃蛇", True, (255, 255, 255), (0, 0, 0))
    title_rect = title_image.get_rect()
    title_rect.center = screen.get_rect().center

    presskey_font = pygame.font.Font(settings.font_name, 15)  # 设置说明文字的字体
    presskey_image = presskey_font.render(
        '按1为手动模式,按2为自动模式,按ESC可退出游戏', True, (255, 255, 255), (0, 0, 0))
    presskey_rect = presskey_image.get_rect()
    presskey_rect.centerx = title_rect.centerx
    presskey_rect.top = title_rect.bottom
    
    screen.fill(settings.bg_color)  # 绘制屏幕
    screen.blit(title_image, title_rect)  # 绘制标题
    screen.blit(presskey_image, presskey_rect)  # 绘制说明文字
    while True:
        check_mode_events(settings)  # 检测键盘
        if settings.game_mode != 0:  # 说明按了1或2，退出循环
            break
        pygame.display.flip()


def show_end(settings, screen):
    """失败结算界面"""
    title_font = pygame.font.Font(settings.font_name, 80)
    game_image = title_font.render('Game', True, (233, 150, 122))
    over_image = title_font.render('Over', True, (233, 150, 122))
    game_rect = game_image.get_rect()
    over_rect = over_image.get_rect()
    screen_rect = screen.get_rect()
    game_rect.midtop = (settings.width / 2, screen_rect.top + 70)
    over_rect.midtop = (settings.width / 2, game_rect.bottom + 50)
    screen.blit(game_image, game_rect)
    screen.blit(over_image, over_rect)
    pygame.display.flip()
    pygame.time.wait(1500)
    settings.game_mode = 0


def draw_grid(settings, screen):
    # 绘制横向线
    for x in range(0, settings.width, settings.cell_size):
        pygame.draw.line(screen, (40, 40, 40), (x, 0), (x, settings.height))
    # 绘制竖向线
    for y in range(0, settings.height, settings.cell_size):
        pygame.draw.line(screen, (40, 40, 40), (0, y), (settings.width, y))


def draw_snake(settings, screen, snake):
    # 头部用白色
    head_index = snake.coords[0]
    x = head_index['x'] * settings.cell_size
    y = head_index['y'] * settings.cell_size
    snake_head_rect = pygame.Rect(
        x, y, settings.cell_size, settings.cell_size)
    pygame.draw.rect(screen, (255, 255, 255), snake_head_rect)
    # 蛇身内部用浅绿，外框用深绿
    for bodies_index in snake.coords[1: -1]:
        x = bodies_index['x'] * settings.cell_size
        y = bodies_index['y'] * settings.cell_size
        snake_part_rect = pygame.Rect(
            x, y, settings.cell_size, settings.cell_size)
        pygame.draw.rect(screen, (0, 155, 0), snake_part_rect)
        snake_part_inner_rect = pygame.Rect(
            x + 4, y + 4, settings.cell_size - 8, settings.cell_size - 8)
        pygame.draw.rect(screen, (0, 255, 0), snake_part_inner_rect)
    # 蛇尾用浅绿
    tail_index = snake.coords[-1]
    x = tail_index['x'] * settings.cell_size
    y = tail_index['y'] * settings.cell_size
    snake_tail_rect = pygame.Rect(
        x, y, settings.cell_size, settings.cell_size)
    pygame.draw.rect(screen, (0, 255, 0), snake_tail_rect)


def draw_apple(apple,settings,screen):
    x = apple.x * settings.cell_size
    y = apple.y * settings.cell_size
    apple_rect = pygame.Rect(
        x, y, settings.cell_size, settings.cell_size)
    pygame.draw.rect(screen, (255, 0, 0), apple_rect)


# 绘制游戏界面
def update_screen(settings, screen, snake,apple):
    screen.fill(settings.bg_color)
    draw_grid(settings, screen)
    draw_apple(apple,settings,screen)
    # 移动蛇
    snake.move_head()  # 加蛇头
    if game_over(snake,settings):
        settings.game_mode = -1
    elif eat_apple(snake,apple):
        apple.spawn(settings)
        draw_apple(apple,settings,screen)
    else:
        del snake.coords[-1]  # 去蛇尾
    draw_snake(settings, screen, snake)
    pygame.display.flip()
    # 暂停一下
    settings.my_clock.tick(settings.clock_frq)


def autoupdate_screen(settings, screen, snake,apple,ai):
    screen.fill(settings.bg_color)
    draw_grid(settings, screen)
    draw_apple(apple,settings,screen)
    # 移动蛇
    snake.automove_head(ai)  # 加蛇头
    if game_over(snake,settings):
        settings.game_mode = -1
    elif eat_apple(snake,apple):
        apple.spawn(settings)
        draw_apple(apple,settings,screen)
    else:
        del snake.coords[-1]  # 去蛇尾
    draw_snake(settings, screen, snake)
    pygame.display.flip()
    # 暂停一下
    settings.my_clock.tick(settings.clock_frq)


def game_over(snake,settings):
    # 碰到左右墙壁
    if (snake.coords[snake.head_index]['x'] == -1 or snake.coords[snake.head_index]['x'] == settings.cell_w):
        return True
    # 碰到上下墙壁
    if (snake.coords[snake.head_index]['y'] == -1 or snake.coords[snake.head_index]['y'] == settings.cell_h):
        return True
    # 碰到自己
    if (snake.coords[snake.head_index] in snake.coords[1:]):
        return True
    return False


def eat_apple(snake,apple):
    if (snake.coords[snake.head_index] == apple.coords):
        return True
    return False