import pygame, random


class Player(object):
    img = pygame.image.load('l7_ship.ppm')
    img.set_colorkey([1, 1, 1])

    def __init__(self, x, y):
        self.x = x
        self.y = y
        self.keys = {}
        self.crash = None
        self.score = 0

    def run(self, screen):
        while 1:
            if self.crash:
                self.y += 1
            else:
                if self.keys.get(pygame.K_LEFT):
                    self.x -= 4
                if self.keys.get(pygame.K_RIGHT):
                    self.x += 4
            screen.blit(self.img, (self.x, self.y))
            yield None


class FallingObject(object):

    def __init__(self, x, player):
        self.x = x
        self.y = -self.img.get_size()[1]
        self.dx = random.randrange(-2, 3)
        self.dy = random.randrange(3, 7)
        self.player = player

    def run(self, screen):
        for self.y in range(self.y, screen_dimensions[1], self.dy):
            self.x += self.dx
            screen.blit(self.img, (self.x, self.y))

            if self.player.crash is None:
                distx = self.x - self.player.x
                disty = self.y - self.player.y
                if distx * distx + disty * disty < 25 * 25:
                    if self.touched():
                        return

            yield None


class Boulder(FallingObject):
    img = pygame.image.load('l7_boulder.ppm')
    img.set_colorkey([1, 1, 1])

    def touched(self):
        self.player.crash = self
        return False


class Star(FallingObject):
    imgs = pygame.image.load('l7_star.ppm')
    imgs.set_colorkey([1, 1, 1])
    imgs = [imgs.subsurface(pygame.Rect(0, y*32, 32, 32)) for y in range(12)]

    def __init__(self, x, player):
        self.img = random.choice(self.imgs)
        FallingObject.__init__(self, x, player)

    def touched(self):
        self.player.score += 1
        return True


title = "My game"
# The framerate of the game (in milliseconds)
framerate = 60
screen_dimensions = (750, 500)

def main():
    # Initialize pygame elements
    screen, clock = init_screen()

    # Build the state
    player = Player(screen_dimensions[0] // 2, screen_dimensions[1] - 40)
    sprites = [player.run(screen)]

    difficulty = 0.97
    font = pygame.font.Font('VeraMoBd.ttf', 24)

    # Even loop
    while True:
        # Add a boulder from time to time
        if random.random() > difficulty:
            if random.random() < 0.12:
                cls = Star
            else:
                cls = Boulder
            obj = cls(random.randrange(0, screen_dimensions[0]), player)
            sprites.append(obj.run(screen))
        if player.crash is None:
            difficulty *= 0.9999

        # Erase the drawing, by drawing a blank background screen
        y2 = 0
        for fy in range(256):
            y1 = y2
            y2 = int(screen_dimensions[1] * (fy + 1) / 256)
            screen.fill((0, 0, 255-fy), (0, y1, screen_dimensions[0], y2 - y1))

        # Ask each sprite to move one step and draw itself
        for sprmover in sprites[:]:
            try:
                sprmover.next()
            except StopIteration:
                sprites.remove(sprmover)

        # Draw the score
        score = font.render(str(player.score), 1, (255, 255, 255))
        screen.blit(score, (30, 20))

        # Update the screen
        pygame.display.flip()
        clock.tick(framerate)

        # Look out for window close events:
        for e in pygame.event.get():
            if e.type == pygame.KEYDOWN:
                player.keys[e.key] = True
            if e.type == pygame.KEYUP:
                player.keys[e.key] = False
            if e.type == pygame.QUIT:
                return


def init_screen():
    pygame.init()
    screen = pygame.display.set_mode(screen_dimensions)
    pygame.display.set_caption(title)
    clock = pygame.time.Clock()
    return screen, clock

main()