"""
Nibbles the video game.
 
Written by Grant Jenks
http://www.grantjenks.com/
 
DISCLAIMER
THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND,
EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.
SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR CORRECTION.
 
Copyright
This work is licensed under the
Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.
To view a copy of this license, visit
http://creativecommons.org/licenses/by-nc-nd/3.0/
or send a letter to Creative Commons, 171 Second Street, Suite 300,
San Francisco, California, 94105, USA
"""
 
import sys, pygame
from random import randrange
from pygame.locals import *
from collections import deque
from itertools import count
 
pygame.init()
 
size = width, height = 480, 480
font = pygame.font.Font(None, 14)
up, right, down, left = (0, -10), (10, 0), (0, 10), (-10, 0)
 
clock = pygame.time.Clock()
screen = pygame.display.set_mode(size)
 
snake_len, snake_dir, food, dead = 20, down, None, False
snake = deque(pygame.Rect(10, 10 + cnt * 10, 10, 10)
              for cnt in range(snake_len))
foreground, background = (255, 255, 255), (0, 0, 0)
 
for counter in count():
 
    event = pygame.event.poll()
 
    if event.type == pygame.QUIT:
        pygame.quit()
        sys.exit()
    elif event.type == KEYDOWN:
        if event.key == K_UP and snake_dir != down:
            snake_dir = up
        elif event.key == K_RIGHT and snake_dir != left:
            snake_dir = right
        elif event.key == K_DOWN and snake_dir != up:
            snake_dir = down
        elif event.key == K_LEFT and snake_dir != right:
            snake_dir = left
        elif event.key == K_r:
            snake_len, snake_dir, food, dead = 20, down, None, False
            snake = deque(pygame.Rect(10, 10 + cnt * 10, 10, 10)
                          for cnt in range(snake_len))
            foreground, background = (255, 255, 255), (0, 0, 0)
        elif event.key == K_q:
            pygame.event.post(pygame.event.Event(QUIT))
 
    if dead:
        continue
 
    next = snake[-1].move(snake_dir)
    if next.left < 0: next.left = width - 10
    if next.left >= width: next.left = 0
    if next.top < 0: next.top = height - 10
    if next.top >= height: next.top = 0
 
    if next in snake:
        dead = True
        foreground, background = background, foreground
    else:
        snake.append(next)
 
        if food and next == food:
            food = None
            snake_len += 1
        else:
            snake.popleft()
 
    if food is None and counter % 50 == 0:
        food = pygame.Rect(randrange(48) * 10, randrange(48) * 10, 10, 10)
 
    screen.fill(background)
    for rect in snake:
        pygame.draw.rect(screen, foreground, rect)
    if food:
        pygame.draw.rect(screen, foreground, food)
    surface = font.render(str(snake_len), True, foreground)
    screen.blit(surface, (0, 0))
 
    pygame.display.flip()
    clock.tick(min(5 + (snake_len / 4), 30))