import pytest
from src.core import Food

def test_food_initialization():
    """Test food initialization"""
    food = Food(20)
    assert food.block_size == 20
    assert food.color == (255, 0, 0)  # Default red color
    assert food.position == (0, 0)  # Default position

def test_food_spawn():
    """Test food spawning mechanics"""
    food = Food(20)
    width, height = 800, 600
    snake_body = [(100, 100), (120, 100)]  # Mock snake body
    
    # Test spawning
    food.spawn(width, height, snake_body)
    
    # Check if food is within bounds
    assert 0 <= food.position[0] < width
    assert 0 <= food.position[1] < height
    
    # Check if position aligns with grid
    assert food.position[0] % food.block_size == 0
    assert food.position[1] % food.block_size == 0
    
    # Check if food doesn't spawn on snake
    assert food.position not in snake_body

def test_food_collision():
    """Test food collision detection"""
    food = Food(20)
    food.position = (100, 100)
    
    # Test collision
    assert food.check_collision((100, 100)) == True
    
    # Test no collision
    assert food.check_collision((120, 120)) == False

def test_food_spawn_full_grid():
    """Test food spawning when grid is mostly occupied"""
    food = Food(20)
    width, height = 60, 60  # Small grid
    
    # Create a snake that occupies all positions except (40, 40)
    all_positions = [(x, y) for x in range(0, 60, 20) for y in range(0, 60, 20)]
    free_spot = (40, 40)
    snake_body = [pos for pos in all_positions if pos != free_spot]
    
    # Verify our test setup is correct
    assert len(snake_body) == len(all_positions) - 1
    assert free_spot not in snake_body
    
    # Spawn food
    food.spawn(width, height, snake_body)
    
    # Food must spawn in the only free spot
    assert food.position == free_spot