# Generated by AI
import pygame
import random
import sys

# Initialize pygame
pygame.init()

# Constants for the game
SCREEN_WIDTH, SCREEN_HEIGHT = 640, 480
CELL_SIZE = 20
GRID_WIDTH, GRID_HEIGHT = SCREEN_WIDTH // CELL_SIZE, SCREEN_HEIGHT // CELL_SIZE
FPS = 10  # Game speed

# Colors
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
GREEN = (0, 255, 0)
RED = (255, 0, 0)

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

class SnakeGame:
    def __init__(self):
        self.screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
        pygame.display.set_caption('Snake Game')
        self.clock = pygame.time.Clock()

        self.snake = [(GRID_WIDTH // 2, GRID_HEIGHT // 2)]
        self.snake_direction = RIGHT
        self.grow = False  # Flag for growing the snake
        self.place_food()

    def place_food(self):
        """Place the food at a random position on the grid."""
        self.food = (random.randint(0, GRID_WIDTH - 1), random.randint(0, GRID_HEIGHT - 1))
        while self.food in self.snake:  # Ensure food is not placed on the snake
            self.food = (random.randint(0, GRID_WIDTH - 1), random.randint(0, GRID_HEIGHT - 1))

    def move_snake(self):
        """Move the snake one cell in the current direction."""
        head_x, head_y = self.snake[0]
        new_head = (head_x + self.snake_direction[0], head_y + self.snake_direction[1])
        if self.grow:
            self.snake.insert(0, new_head)  # Grow the snake
        else:
            self.snake.insert(0, new_head)  # Move the head
            self.snake.pop()  # Remove the tail
        self.grow = False

        # Detect collisions with the walls
        if not (0 <= new_head[0] < GRID_WIDTH) or not (0 <= new_head[1] < GRID_HEIGHT):
            self.game_over()

        # Detect collisions with the snake itself
        if new_head in self.snake[1:]:
            self.game_over()

    def check_food_collision(self):
        """Check if the snake has eaten the food."""
        if self.snake[0] == self.food:
            self.place_food()
            self.grow = True

    def draw(self):
        """Draw the game state to the screen."""
        self.screen.fill(BLACK)
        for segment in self.snake:
            pygame.draw.rect(self.screen, GREEN, (segment[0] * CELL_SIZE, segment[1] * CELL_SIZE, CELL_SIZE, CELL_SIZE))
        pygame.draw.rect(self.screen, RED, (self.food[0] * CELL_SIZE, self.food[1] * CELL_SIZE, CELL_SIZE, CELL_SIZE))
        pygame.display.flip()

    def game_over(self):
        """Handle the game over scenario."""
        self.screen.fill(BLACK)
        font = pygame.font.SysFont(None, 72)
        text = font.render("Game Over", True, WHITE)
        text_rect = text.get_rect(center=(SCREEN_WIDTH // 2, SCREEN_HEIGHT // 2))
        self.screen.blit(text, text_rect)
        pygame.display.flip()
        pygame.time.wait(2000)
        pygame.quit()
        sys.exit()

    def run(self):
        """Main game loop."""
        while True:
            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    self.game_over()
                elif event.type == pygame.KEYDOWN:
                    if event.key == pygame.K_UP and self.snake_direction != DOWN:
                        self.snake_direction = UP
                    elif event.key == pygame.K_DOWN and self.snake_direction != UP:
                        self.snake_direction = DOWN
                    elif event.key == pygame.K_LEFT and self.snake_direction != RIGHT:
                        self.snake_direction = LEFT
                    elif event.key == pygame.K_RIGHT and self.snake_direction != LEFT:
                        self.snake_direction = RIGHT

            self.move_snake()
            self.check_food_collision()
            self.draw()
            self.clock.tick(FPS)

if __name__ == '__main__':
    game = SnakeGame()
    game.run()