#
import pygame
from pygame.locals import * 
from random import randint
import math

class Paddle(pygame.sprite.Sprite):
    WIDTH, HEIGHT = 15, 300
    SPEED = 20.
    def __init__(self, pos):
        pygame.sprite.Sprite.__init__(self)
        self.rect = Rect(0,0, Paddle.WIDTH, Paddle.HEIGHT)
        self.rect.center = pos
        self.image = pygame.Surface(self.rect.size)
        self.image.fill(Color("gray80"))
    def handle_keystate(self, keys):
        if keys[pygame.K_w]:
            self.rect.top -= self.SPEED
        elif keys[pygame.K_s]:
            self.rect.top += self.SPEED

class Ball(pygame.sprite.Sprite):
    SPEED = 10.
    def __init__(self, game):
        pygame.sprite.Sprite.__init__(self)
        self.game = game
        self.rect = Rect(0,0,20,20)
        self.image = pygame.Surface(self.rect.size)
        self.image.fill(Color("gray20"))
        self.velx, self.vely = self.SPEED, self.SPEED
    def draw(self):
        self.game.screen.blit(self.image, self.rect)
    def reset(self):
        # to center
        self.rect.center = self.game.screen.get_rect().center
        
        # random direction, with same initial speed
        angle = math.radians(randint(0,360))
        self.velx = math.cos(angle) * self.SPEED
        self.vely = math.sin(angle) * self.SPEED        

    def update(self):    
        # move
        self.rect.x += self.velx
        self.rect.y += self.vely
        # bounce walls
        if self.rect.top <= 0:            
            self.vely *= -1
        if self.rect.bottom >= self.game.screen.get_rect().bottom:
            self.vely *= -1

        # offscreen
        if not self.rect.colliderect(self.game.screen.get_rect()):
            if self.rect.left <= 0:
                print "ai scores"
            else:
                print "human scores"
            self.reset()        

    def handle_collision(self, other):
        self.velx *= -1
        self.vely *= -1



class GameMain():
    """game Main. entry point. handles intialization of game and graphics, as well as game loop."""    
    done = False
    color_bg = Color('gray30') # or also: Color(50,50,50) , or: Color('#fefefe')
    
    def __init__(self, width=800, height=600):
        """
        """
        pygame.init()

        self.width, self.height = width, height
        self.screen = pygame.display.set_mode(( self.width, self.height ))
        self.clock = pygame.time.Clock()       

        self.player = Paddle(( 50 ,300))
        self.ai = Paddle(( self.screen.get_rect().right - 50,300))
        self.paddles = pygame.sprite.Group()
        self.ball = Ball(self)
        self.paddles.add( self.player, self.ai)
    
    def main_loop(self):
        """Game() main loop."""
        while not self.done:
            self.handle_events()        
            # move ball
            self.ball.update()

            for p in self.paddles:
                if self.ball.rect.colliderect(p.rect):
                    self.ball.handle_collision(p)

            self.draw()
            self.clock.tick(60)
                
    def draw(self):
        """draw screen"""

        self.screen.fill( self.color_bg )

        self.paddles.draw(self.screen)
        self.ball.draw()

        pygame.display.flip()
        
    def handle_events(self):
        """handle events: keyboard, mouse, etc."""
        events = pygame.event.get()

        # keystates
        keys = pygame.key.get_pressed()
        self.player.handle_keystate(keys)
        
        # events
        for event in events:
            if event.type == pygame.QUIT: self.done = True
            # event: keydown
            elif event.type == KEYDOWN:
                if event.key == K_ESCAPE: self.done = True                
                elif event.key == K_SPACE:
                    self.ball.reset()

if __name__ == "__main__":         
    game = GameMain()
    game.main_loop()