import pygame
import random

# Define colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)

# Set the dimensions of the screen
SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

# Define the Player class
class Player(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface([20, 20])
        self.image.fill(WHITE)
        self.rect = self.image.get_rect()

    def update(self):
        # Move the player based on user input
        keys = pygame.key.get_pressed()
        if keys[pygame.K_LEFT]:
            self.rect.x -= 5
        elif keys[pygame.K_RIGHT]:
            self.rect.x += 5

        # Keep the player within the screen bounds
        if self.rect.x < 0:
            self.rect.x = 0
        elif self.rect.x > SCREEN_WIDTH - 20:
            self.rect.x = SCREEN_WIDTH - 20

# Define the Enemy class
class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        super().__init__()
        self.image = pygame.Surface([10, 10])
        self.image.fill(BLACK)
        self.rect = self.image.get_rect()

        # Choose a random starting position and velocity for the enemy
        self.rect.x = random.randrange(SCREEN_WIDTH - 10)
        self.rect.y = random.randrange(-100, -10)
        self.velocity = random.randrange(1, 4)

    def update(self):
        # Move the enemy down the screen
        self.rect.y += self.velocity

        # Respawn the enemy if it goes off the bottom of the screen
        if self.rect.y > SCREEN_HEIGHT:
            self.rect.x = random.randrange(SCREEN_WIDTH - 10)
            self.rect.y = random.randrange(-100, -10)
            self.velocity = random.randrange(1, 4)

# Initialize Pygame
pygame.init()

# Set the dimensions of the screen
screen = pygame.display.set_mode([SCREEN_WIDTH, SCREEN_HEIGHT])

# Set the title of the window
pygame.display.set_caption('Gun Game')

# Create the player sprite
player = Player()
all_sprites = pygame.sprite.Group()
all_sprites.add(player)

# Create the enemy sprites
enemies = pygame.sprite.Group()
for i in range(10):
    enemy = Enemy()
    all_sprites.add(enemy)
    enemies.add(enemy)

# Set the clock for the game loop
clock = pygame.time.Clock()

# Set the game loop condition
game_over = False

# Set the score to zero
score = 0

# Start the game loop
while not game_over:
    # Handle events
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            game_over = True

        # Handle shooting events
        if event.type == pygame.MOUSEBUTTONDOWN:
            # Create a bullet sprite
            bullet = pygame.sprite.Sprite()
            bullet.image = pygame.Surface([4, 10])
            bullet.image.fill(WHITE)
            bullet.rect = bullet.image.get_rect()
            bullet.rect.x = player.rect.x + 8
            bullet.rect.y = player.rect.y - 10
            all_sprites.add(bullet)

    # Update all sprites
    all_sprites.update()

    # Check for collisions between bullets and enemies
    hits = pygame.sprite.groupcollide(enemies, all_sprites, False, True)
    for enemy in hits:
        # Respawn the enemy and add to the score
        enemy.rect.x = random.randrange(SCREEN_WIDTH - 10)