import pygame
import random
import sys

# 初始化pygame
pygame.init()

# 窗口基础设置
WIDTH, HEIGHT = 800, 600
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("2D移动射击游戏")
clock = pygame.time.Clock()
FPS = 60

# 颜色定义
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 120, 255)

# 玩家类
class Player:
    def __init__(self):
        self.x = WIDTH // 2
        self.y = HEIGHT // 2
        self.radius = 20
        self.speed = 5
        self.hp = 5
        self.score = 0

    def move(self):
        keys = pygame.key.get_pressed()
        # 全部改为小写K_w K_s K_a K_d
        if keys[pygame.K_w] and self.y - self.radius > 0:
            self.y -= self.speed
        if keys[pygame.K_s] and self.y + self.radius < HEIGHT:
            self.y += self.speed
        if keys[pygame.K_a] and self.x - self.radius > 0:
            self.x -= self.speed
        if keys[pygame.K_d] and self.x + self.radius < WIDTH:
            self.x += self.speed

    def draw(self):
        pygame.draw.circle(screen, BLUE, (int(self.x), int(self.y)), self.radius)
        # 瞄准线
        mx, my = pygame.mouse.get_pos()
        pygame.draw.line(screen, WHITE, (self.x, self.y), (mx, my), 2)

# 子弹类
class Bullet:
    def __init__(self, x, y, target_x, target_y):
        self.x = x
        self.y = y
        speed = 12
        # 计算方向向量
        dx = target_x - x
        dy = target_y - y
        length = (dx**2 + dy**2)**0.5
        self.vx = dx / length * speed
        self.vy = dy / length * speed
        self.radius = 6

    def update(self):
        self.x += self.vx
        self.y += self.vy

    def draw(self):
        pygame.draw.circle(screen, WHITE, (int(self.x), int(self.y)), self.radius)

    def out_of_screen(self):
        if self.x < 0 or self.x > WIDTH or self.y < 0 or self.y > HEIGHT:
            return True
        return False

# 敌人小怪类
class Enemy:
    def __init__(self):
        # 随机在屏幕四边出生
        side = random.randint(0, 3)
        if side == 0:
            self.x = random.randint(0, WIDTH)
            self.y = -20
        elif side == 1:
            self.x = WIDTH + 20
            self.y = random.randint(0, HEIGHT)
        elif side == 2:
            self.x = random.randint(0, WIDTH)
            self.y = HEIGHT + 20
        else:
            self.x = -20
            self.y = random.randint(0, HEIGHT)
        self.radius = 16
        self.speed = 2.2

    def update(self, px, py):
        # 朝玩家移动
        dx = px - self.x
        dy = py - self.y
        dist = (dx**2 + dy**2)**0.5
        if dist != 0:
            self.x += dx / dist * self.speed
            self.y += dy / dist * self.speed

    def draw(self):
        pygame.draw.circle(screen, RED, (int(self.x), int(self.y)), self.radius)

# 主游戏逻辑
def main():
    player = Player()
    bullet_list = []
    enemy_list = []
    spawn_enemy_timer = 0
    game_over = False
    font = pygame.font.SysFont(None, 36)

    while True:
        clock.tick(FPS)
        screen.fill(BLACK)

        # 事件监听
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
            # 鼠标左键发射子弹
            if event.type == pygame.MOUSEBUTTONDOWN and event.button == 1 and not game_over:
                mx, my = pygame.mouse.get_pos()
                bullet = Bullet(player.x, player.y, mx, my)
                bullet_list.append(bullet)

        if not game_over:
            # 玩家移动
            player.move()

            # 定时生成敌人
            spawn_enemy_timer += 1
            if spawn_enemy_timer > 70:
                enemy_list.append(Enemy())
                spawn_enemy_timer = 0

            # 更新子弹
            for b in bullet_list[:]:
                b.update()
                if b.out_of_screen():
                    bullet_list.remove(b)

            # 更新敌人
            for e in enemy_list:
                e.update(player.x, player.y)

            # 子弹击中敌人判定
            for b in bullet_list[:]:
                hit = False
                for e in enemy_list[:]:
                    dist = ((b.x - e.x)**2 + (b.y - e.y)**2)**0.5
                    if dist < b.radius + e.radius:
                        bullet_list.remove(b)
                        enemy_list.remove(e)
                        player.score += 10
                        hit = True
                        break
                if hit:
                    break

            # 敌人撞到玩家扣血
            for e in enemy_list[:]:
                dist = ((player.x - e.x)**2 + (player.y - e.y)**2)**0.5
                if dist < player.radius + e.radius:
                    enemy_list.remove(e)
                    player.hp -= 1
                    if player.hp <= 0:
                        game_over = True

            # 绘制所有元素
            player.draw()
            for b in bullet_list:
                b.draw()
            for e in enemy_list:
                e.draw()

            # 绘制血量与分数
            hp_text = font.render(f"HP: {player.hp}", True, GREEN)
            score_text = font.render(f"Score: {player.score}", True, WHITE)
            screen.blit(hp_text, (10, 10))
            screen.blit(score_text, (10, 45))

        else:
            # 游戏结束界面
            over_font = pygame.font.SysFont(None, 72)
            over_text = over_font.render("GAME OVER", True, RED)
            final_score = font.render(f"Final Score: {player.score}", True, WHITE)
            restart_text = font.render("Press R to Restart", True, WHITE)
            screen.blit(over_text, (WIDTH//2 - 180, HEIGHT//2 - 80))
            screen.blit(final_score, (WIDTH//2 - 130, HEIGHT//2))
            screen.blit(restart_text, (WIDTH//2 - 160, HEIGHT//2 + 50))

            # 重启按键 K_r 小写
            keys = pygame.key.get_pressed()
            if keys[pygame.K_r]:
                main()

        pygame.display.flip()

if __name__ == "__main__":
    main()