#!/usr/bin/env python
import sys, pygame, random


class Snake:

    def __init__(self, length=10,grid_width=50,grid_height=50, grid_pts=15,fps=10):
        self.grid_width=grid_width
        self.grid_height=grid_height
        self.grid_pts=grid_pts
        self.fps=fps
        self.snake=[(0,0)]*length
        self.direction=3 # Like clock (12=up, 3=right, 6=bottom, 9=left)
        pygame.init()
        self.screen=pygame.display.set_mode((grid_width*grid_pts,grid_height*grid_pts))

    def draw_pts(self,x,y,color=(255,255,255)):
        rect=pygame.Rect(self.grid_pts*x, self.grid_pts*y, self.grid_pts, self.grid_pts)
        pygame.draw.rect(self.screen,color,rect, 0)


    def new_apple(self):
        self.apple=(random.randint(0,grid_width),random.randint(0,grid_height))
        while self.apple in self.snake:
            self.apple=(random.randint(0,grid_width),random.randint(0,grid_height))

    def move(self):
        # Update tail
        if len(self.snake)>1:
            tmp=self.snake[0]
            for i in range(1,len(self.snake)):
                newtmp=self.snake[i]
                self.snake[i]=tmp
                tmp=newtmp
        # Update head
        h=self.snake[0] # Head
        if self.direction==3:
            self.snake[0]=(h[0]+1,h[1])
        elif self.direction==9:
            self.snake[0]=(h[0]-1,h[1])
        elif self.direction==12:
            self.snake[0]=(h[0],h[1]-1)
        else:
            self.snake[0]=(h[0],h[1]+1)

    def draw_snake(self):
        for elt in self.snake:
            self.draw_pts(elt[0],elt[1])

    def run(self):
        clock = pygame.time.Clock()
        self.direction=6
        while True:
            for event in pygame.event.get():
                if event.type == pygame.QUIT: 
                    pygame.quit()
                    sys.exit()
                elif event.type == pygame.KEYDOWN:
                    if event.key == pygame.K_LEFT and self.direction != 3:
                        self.direction=9
                    if event.key == pygame.K_RIGHT and self.direction != 9:
                        self.direction=3
                    if event.key == pygame.K_UP and self.direction != 6:
                        self.direction=12
                    if event.key == pygame.K_DOWN and self.direction != 12:
                        self.direction=6
            
            self.screen.fill((0,0,0))
            self.draw_snake()
            self.move()
            pygame.display.flip()
            clock.tick(self.fps)


game=Snake()
game.run()