snake.py

import pygame
import random
import sys

CELL_SIZE = 20          
GRID_WIDTH = 30         
GRID_HEIGHT = 20        
WIDTH = CELL_SIZE * GRID_WIDTH
HEIGHT = CELL_SIZE * GRID_HEIGHT
FPS_START = 8           
SPEED_INCREMENT = 0.5   
WRAP_AROUND = False     

WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
DARK_GREEN = (10, 120, 10)
GREEN = (34, 177, 76)
RED = (200, 30, 30)
GRAY = (50, 50, 50)

UP = (0, -1)
DOWN = (0, 1)
LEFT = (-1, 0)
RIGHT = (1, 0)

pygame.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Snake (pygame)")
clock = pygame.time.Clock()
font = pygame.font.SysFont(None, 28)
big_font = pygame.font.SysFont(None, 56)

def draw_cell(pos, color):
    x, y = pos
    rect = pygame.Rect(x * CELL_SIZE, y * CELL_SIZE, CELL_SIZE, CELL_SIZE)
    pygame.draw.rect(screen, color, rect)

def random_empty_cell(snake):
    available = [(x, y) for x in range(GRID_WIDTH) for y in range(GRID_HEIGHT) if (x, y) not in snake]
    return random.choice(available) if available else None

def step_head(head, direction):
    x, y = head
    dx, dy = direction
    return (x + dx, y + dy)

def in_bounds(pos):
    x, y = pos
    return 0 <= x < GRID_WIDTH and 0 <= y < GRID_HEIGHT

def draw_grid():
    for x in range(0, WIDTH, CELL_SIZE):
        pygame.draw.line(screen, GRAY, (x, 0), (x, HEIGHT))
    for y in range(0, HEIGHT, CELL_SIZE):
        pygame.draw.line(screen, GRAY, (0, y), (WIDTH, y))

def show_text(text, size=28, color=WHITE, center=None):
    f = pygame.font.SysFont(None, size)
    surf = f.render(text, True, color)
    rect = surf.get_rect()
    if center:
        rect.center = center
    else:
        rect.topleft = (10, 10)
    screen.blit(surf, rect)

def game_loop():
    mid_x = GRID_WIDTH // 2
    mid_y = GRID_HEIGHT // 2
    snake = [(mid_x - 1, mid_y), (mid_x, mid_y)]  
    direction = RIGHT
    pending_direction = RIGHT  
    score = 0
    fps = FPS_START

    apple = random_empty_cell(snake)

    running = True
    game_over = False

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

            if event.type == pygame.KEYDOWN:
                if event.key in (pygame.K_UP, pygame.K_w):
                    pending_direction = UP
                elif event.key in (pygame.K_DOWN, pygame.K_s):
                    pending_direction = DOWN
                elif event.key in (pygame.K_LEFT, pygame.K_a):
                    pending_direction = LEFT
                elif event.key in (pygame.K_RIGHT, pygame.K_d):
                    pending_direction = RIGHT
                elif event.key == pygame.K_r and game_over:
                    return True  
                elif event.key == pygame.K_ESCAPE:
                    pygame.quit()
                    sys.exit()

        if not game_over:
            opp = (-direction[0], -direction[1])
            if pending_direction != opp:
                direction = pending_direction

            new_head = step_head(snake[-1], direction)

            if WRAP_AROUND:
                new_x = new_head[0] % GRID_WIDTH
                new_y = new_head[1] % GRID_HEIGHT
                new_head = (new_x, new_y)
            else:
                if not in_bounds(new_head):
                    game_over = True

            if not game_over and new_head in snake:
                game_over = True

            if not game_over:
                snake.append(new_head)

                if apple and new_head == apple:
                    score += 1
                    fps += SPEED_INCREMENT
                    apple = random_empty_cell(snake)
                else:
                    snake.pop(0)

        screen.fill(BLACK)
        for segment in snake[:-1]:
            draw_cell(segment, DARK_GREEN)
        if snake:
            draw_cell(snake[-1], GREEN)  

        if apple:
            draw_cell(apple, RED)

        draw_grid()

        show_text(f"Score: {score}")

        if game_over:
            show_text("GAME OVER", size=56, color=WHITE, center=(WIDTH//2, HEIGHT//2 - 20))
            show_text("Press R to restart or ESC to quit", size=28, color=WHITE, center=(WIDTH//2, HEIGHT//2 + 30))

        pygame.display.flip()

        if not game_over:
            clock.tick(fps)
        else:
            clock.tick(10)

def main_menu():
    while True:
        screen.fill(BLACK)
        show_text("Snake (pygame)", size=48, color=WHITE, center=(WIDTH//2, HEIGHT//2 - 80))
        show_text("Arrow keys or WASD to move", size=28, color=WHITE, center=(WIDTH//2, HEIGHT//2 - 20))
        wrap_text = "Wrap-around: ON" if WRAP_AROUND else "Wrap-around: OFF"
        show_text(wrap_text + "  (toggle in code)", size=20, color=WHITE, center=(WIDTH//2, HEIGHT//2 + 10))
        show_text("Press SPACE to start, ESC to quit", size=28, color=WHITE, center=(WIDTH//2, HEIGHT//2 + 60))
        pygame.display.flip()

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                pygame.quit()
                sys.exit()
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_SPACE:
                    return
                if event.key == pygame.K_ESCAPE:
                    pygame.quit()
                    sys.exit()
        clock.tick(10)

def main():
    while True:
        main_menu()
        restart = game_loop()
        if not restart:
            break

if __name__ == "__main__":
    main()