snake game

import pygame
import time
import random

snake_speed = 15
height = 720
width = 480

BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)

pygame.init()
game_window = pygame.display.set_mode((width, height))

pygame.display.set_caption("Snake")

fps = pygame.time.Clock() #frames per second = fps

snake_position = [100, 50]

#defining first 4 blocks of snake body
snake_body = [[100, 50],
            [90, 50],
            [80, 50],
            [70, 50]
            ]

fruit_position = [random.randrange(1, (width//10)) * 10,
                 random.randrange(1, (height//10)) * 10]

fruit_spawn = True

direction = 'RIGHT'

change_to = direction

#initial score
score = 0

#function to display score
def show_score(choice, color, font, size):
    score_font = pygame.font.SysFont(font, size)
    score_surface = score_font.render('Score: ' + str(score), True, color)
    #creating a rectangular object for the text
    score_rect = score_surface.get_rect()
    #displaying text
    game_window.blit(score_surface, score_rect)

#game over function
def game_over():
    my_font = pygame.font.SysFont('times new roman', 50)
    #defining surface on which to draw text
    game_over_surface = my_font.render('Your score is:' + str(score), True, RED)
    #creating a rectangular object for the text
    game_over_rect = game_over_surface.get_rect()
    #setting potision of the text
    game_over_rect.midtop = (width/2, height/4)
    game_window.blit(game_over_surface, game_over_rect)
    pygame.display.flip()
    #adding line to quit program after 2 seconds
    time.sleep(2) #value is time in seconds
    #deactivating pygame library
    pygame.quit()
    #qutting the program
    quit()

#main
while True:
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                change_to = 'UP'
            if event.key == pygame.K_DOWN:
                change_to = 'DOWN'
            if event.key == pygame.K_LEFT:
                change_to = 'LEFT'
            if event.key == pygame.K_RIGHT:
                change_to == 'RIGHT'
    #if two keys pressed simultaneously,  we dont want
    #snake to move in two different directions

    if change_to == 'UP' and direction != 'DOWN':
        direction = 'UP'
    if change_to == 'DOWN' and direction != 'UP':
        direction = 'DOWN'
    if change_to == 'LEFT' and direction != 'RIGHT':
        direction = 'LEFT'
    if change_to == 'RIGHT' and direction != 'LEFT':
        direction = 'RIGHT'

    #moving the snake
    if direction == 'UP':
        snake_position[1] -= 10
    if direction == 'DOWN':
        snake_position[1] += 10
    if direction == 'LEFT':
        snake_position[0] -= 10
    if direction == 'RIGHT':
        snake_position[0] += 10

    #snake body growing mechanism
    #if fruit and snake collide then scores increase by 1
    snake_body.insert(0, list(snake_position))
    if snake_position[0] == fruit_position[0] and snake_position[1] == fruit_position[1]:
        score += 1
        fruit_spawn = False
    else:
        snake_body.pop()

    if not fruit_spawn:
        fruit_position = [random.randrange(1, (width//10)) * 10,
                        random.randrange(1, (height//10)) * 10]

    fruit_spawn = True
    game_window.fill(BLACK)

    for pos in snake_body:
        pygame.draw.rect(game_window, GREEN, pygame.Rect(pos[0], pos[1], 10, 10))

    pygame.draw.rect(game_window, WHITE, pygame.Rect(fruit_position[0], fruit_position[1], 10, 10))

    #game over condition
    if snake_position[0] < 0 or snake_position[0] > width-10:
        game_over()
    if snake_position[1] < 0 or snake_position[1] > height-10:
        game_over()

    #touching snake body
    for block in snake_body[1:]:
        if snake_position[0] == block[0] and snake_position[1] == block[1]:
            game_over()

    #displaying score continuously
    show_score(1, WHITE, 'times new roman', 20)

    #updating window
    pygame.display.update()

    #refresh rate/frame rate per second
    fps.tick(snake_speed)