import pygame, sys, random

pygame.init()

screen_width = 800
screen_height = 600
screen = pygame.display.set_mode([screen_width, screen_height])
all_sprites_list = pygame.sprite.Group()
block_list = pygame.sprite.Group()
bullet_list = pygame.sprite.Group()
BLACK    = (   0,   0,   0)
WHITE    = ( 255, 255, 255)
background = pygame.image.load('space.jpg')
pygame.display.set_caption("Alien Invasion!")
explosion = pygame.mixer.Sound('explosion.wav')
score = 0

class Block(pygame.sprite.Sprite):
    def __init__(self, color):
        pygame.sprite.Sprite.__init__(self)

        self.image = pygame.image.load("spaceship.png")
        self.rect = self.image.get_rect()

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)

        self.x=0
        self.y=0
        self.image = pygame.image.load("alien.png")
        self.rect = self.image.get_rect()

    def update(self):

        pos = pygame.mouse.get_pos()
        self.rect.x = pos[0]

    def render(self):

        if (self.currentImage==0):
            screen.blit(self.image, (self.x, self.y))

class Bullet(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("bullet.png")
        self.rect = self.image.get_rect()

    def update(self):

        self.rect.y -= 3

for i in range(30):
    block = Block(BLACK)
    block.rect.x = random.randrange(screen_width)
    block.rect.y = random.randrange(330)
    block_list.add(block)
    all_sprites_list.add(block)

player = Player()

all_sprites_list.add(player)

done = False

clock = pygame.time.Clock()

player.rect.y = 480

k_space = False

while True:
    for event in pygame.event.get():
        if (event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE) or pygame.QUIT:
            pygame.quit()
            sys.exit()

        elif event.type == pygame.KEYDOWN and event.key == pygame.K_SPACE:
            k_space = True

    if k_space:
        bullet = Bullet()
        bullet.rect.x = player.rect.x
        bullet.rect.y = player.rect.y
        all_sprites_list.add(bullet)
        bullet_list.add(bullet)

    k_space = False

    all_sprites_list.update()

    for bullet in bullet_list:

        block_hit_list = pygame.sprite.spritecollide(bullet, block_list, True)

        for block in block_hit_list:
            explosion.play()
            bullet_list.remove(bullet)
            all_sprites_list.remove(bullet)
            score += 10

        if bullet.rect.y < -10:
            bullet_list.remove(bullet)
            all_sprites_list.remove(bullet)

    font = pygame.font.Font(None, 36)
    text = font.render("Score: " + str(score), True, WHITE)
    textpos = text.get_rect(centerx=screen.get_width()/12)

    screen.blit(background, (0,0))

    screen.blit(text, textpos)

    all_sprites_list.draw(screen)

    pygame.display.update()

    clock.tick(80)

pygame.quit()