main.py

import pygame
import sys
import random
from pygame.math import Vector2


class SNAKE:
    def __init__(self):
        self.body = [Vector2(5, 10), Vector2(4, 10), Vector2(3, 10)]
        self.direction = Vector2(0, 0)
        self.new_block = False
        self.crunch = pygame.mixer.Sound("munch.mp3")

    def draw_snake(self):
        for block in self.body:
            # create a rect
            x_pos = int(block.x * cell_size)
            y_pos = int(block.y * cell_size)
            block_rect = pygame.Rect(x_pos, y_pos, cell_size, cell_size)
            # draw the rectangle
            pygame.draw.rect(screen, (183, 191, 122), block_rect)

    def move_snake(self):
        if self.new_block == True:
            body_copy = self.body[:]
            body_copy.insert(0, body_copy[0] + self.direction)
            self.body = body_copy[:]
            self.new_block = False
        else:
            body_copy = self.body[:-1]
            body_copy.insert(0, body_copy[0] + self.direction)
            self.body = body_copy[:]

    def add_block(self):
        self.new_block = True

    def play_crunch_sound(self):
        self.crunch.play()
    
    def reset(self):
        self.body = [Vector2(5, 10), Vector2(4, 10), Vector2(3, 10)]
        self.direction = Vector2(0, 0)

class FRUIT:
    def __init__(self):
        # randomize the fruit position
        self.randomize()

    def draw_fruit(self):
        # create a rectangle
        fruit_rect = pygame.Rect(
            int(self.pos.x * cell_size), int(self.pos.y * cell_size), cell_size, cell_size)
        # draw the rectangle
        screen.blit(apple, fruit_rect)

    def randomize(self):
        self.x = random.randint(0, cell_number - 1)
        self.y = random.randint(0, cell_number - 1)
        self.pos = Vector2(self.x, self.y)

class MAIN: 
    def __init__(self):
        self.snake = SNAKE()
        self.fruit = FRUIT()

    def update(self):
        self.snake.move_snake()
        self.check_collision()
        self.check_fail()

    def draw_elements(self):
        self.draw_grass()
        self.fruit.draw_fruit()
        self.snake.draw_snake()
        self.draw_score()
    
    def check_collision(self):
        if self.fruit.pos == self.snake.body[0]:
            # reposition the fruit
            self.fruit.randomize()
            #add block to snake
            self.snake.add_block()
            self.snake.play_crunch_sound()
        for block in self.snake.body[1:]:
            if block == self.fruit.pos:
                self.fruit.randomize

    def check_fail(self):
        # check if the snake is outside of borders
        if not 0 <= self.snake.body[0].x < cell_number or not 0 <= self.snake.body[0].y < cell_number:
            self.game_over()
        # check if snake has hit itself
        for block in self.snake.body[1:]:
            if block == self.snake.body[0]:
                self.game_over()

    def game_over(self):
        self.snake.reset()

    def draw_grass(self):
        grass_colour = (167, 209, 61)
        for row in range(cell_number):
            if row % 2 == 0:
                for col in range(cell_number):
                    if col % 2 == 0:
                        grass_rect = pygame.Rect(col * cell_size, row * cell_size, cell_size, cell_size)
                        pygame.draw.rect(screen, grass_colour, grass_rect)
            else:
                for col in range(cell_number):
                    if col % 2 != 0:
                        grass_rect = pygame.Rect(col * cell_size, row * cell_size, cell_size, cell_size)
                        pygame.draw.rect(screen, grass_colour, grass_rect)
             
    def draw_score(self):
        score_text = str(len(self.snake.body) - 3)
        score_surface = game_font.render(score_text, True, (56, 74, 12))
        score_x = int(cell_size * cell_number - 60)
        score_y = int(cell_size * cell_number - 40)
        score_rect = score_surface.get_rect(center = (score_x, score_y))
        apple_rect = apple.get_rect(midright = (score_rect.left, score_rect.centery))
        bg_rect = pygame.Rect(apple_rect.left, apple_rect.top, apple_rect.width + score_rect.width + 6, apple_rect.height)
    
        pygame.draw.rect(screen, (167, 209, 61), bg_rect)    
        screen.blit(score_surface, score_rect)
        screen.blit(apple, apple_rect)
        pygame.draw.rect(screen, (56, 74, 12), bg_rect, 2)

pygame.mixer.pre_init(44100, -16, 2 ,512)
pygame.init()
cell_size = 30
cell_number = 20
screen = pygame.display.set_mode((cell_number * cell_size, cell_number * cell_size))
clock = pygame.time.Clock()
apple = pygame.image.load("apple.png").convert_alpha()
game_font = pygame.font.Font(None, 25)


SCREEN_UPDATE = pygame.USEREVENT
pygame.time.set_timer(SCREEN_UPDATE, 150)

main_game = MAIN()

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()

        if event.type == SCREEN_UPDATE:
            main_game.update()

        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                if main_game.snake.direction.y != 1:
                    main_game.snake.direction = Vector2(0, -1)
            if event.key == pygame.K_DOWN:
                if main_game.snake.direction.y != -1:
                    main_game.snake.direction = Vector2(0, 1)
            if event.key == pygame.K_LEFT:
                if main_game.snake.direction.x != 1:
                    main_game.snake.direction = Vector2(-1, 0)
            if event.key == pygame.K_RIGHT:
                if main_game.snake.direction.x != -1:
                    main_game.snake.direction = Vector2(1, 0)        
    screen.fill((175, 215, 70))
    main_game.draw_elements()
    pygame.display.update()
    clock.tick(60)