import pygame, random
pygame.init()

screen = pygame.display.set_mode((640, 480))

class Ship(pygame.sprite.Sprite):
    def __init__(self, bullet):
        self.bullet = bullet
        pygame.sprite.Sprite.__init__(self)
        self.screen = screen
        self.image = pygame.image.load("ship.jpg")
        self.image = self.image.convert()
        self.rect = self.image.get_rect()
        self.rect.center = (50, 240)
        self.dx = 10
        self.dy = 10

        if not pygame.mixer:
            print "problem with sound"
        else:
            pygame.mixer.init()
            self.sndCrash = pygame.mixer.Sound("shipcrash2.ogg")
            self.sndFire = pygame.mixer.Sound("gunfire2.ogg")
            self.sndExplosion = pygame.mixer.Sound("explosion2.ogg")

    def update(self):
        self.checkKeys()
        self.checkBounds()

    def checkKeys(self):
        keys = pygame.key.get_pressed()
        if keys[pygame.K_UP]:
            self.rect.centery -= self.dy
        if keys[pygame.K_DOWN]:
            self.rect.centery += self.dy
        if keys[pygame.K_SPACE]:
            self.bullet.x = self.rect.centerx
            self.bullet.y = self.rect.centery
            self.bullet.speed = self.dx



          
      
    def checkBounds(self):
        screen = self.screen
        if self.rect.centery > 420:
            self.rect.centery = 420
        if self.rect.centery < 50:
            self.rect.centery = 50

class Bullet(pygame.sprite.Sprite):
    def __init__(self, screen):
        pygame.sprite.Sprite.__init__(self)
        self.screen = screen
      
        self.image = pygame.image.load("bullet.jpg")
        self.image = self.image.convert()
        self.rect = self.image.get_rect()
        self.rect.center = (-100, -100)
        self.speed = 0
        self.reset()

        if not pygame.mixer:
            print "problem with sound"
        else:
            pygame.mixer.init()
            self.sndImpact = pygame.mixer.Sound("impact2.ogg")


    def update(self):
        self.position()
        self.checkBounds()
        self.rect.center = (self.x, self.y)

    def position(self):
        self.x += self.speed

    def checkBounds(self):
        screen = self.screen
        if self.rect.left > screen.get_width():
            self.reset()
  

    def reset(self):
        self.x = -100
        self.y = -100
        self.speed = 0

class Ufo(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("ufo.jpg")
        self.image = self.image.convert()
        self.rect = self.image.get_rect()
        self.reset()

    def update(self):
        self.rect.centerx -= self.dx
        self.rect.centery -= self.dy
        if self.rect.right <= 0:
            self.reset()
  
    def reset(self):
        self.rect.left = screen.get_width()
        self.rect.centery = random.randrange(0, screen.get_height())
        self.dy = random.randrange(-2, 2)
        self.dx = random.randrange(4, 6)

class UfoBullet(pygame.sprite.Sprite):
    def __init__(self, screen):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.image.load("enemybullet.jpg")
        self.image = self.image.convert()
        self.rect = self.image.get_rect()
        self.reset()
        self.rect.centerx = 490
        self.dx = 10

        def update(self):
            self.rect.centerx -= self.dx
            if self.rect.right <= 0:
                self.reset()

        def reset(self):
            self.x = -50
            self.dx = 10