# Draw rainbows!!!!
rainbow_colors = ['Red', 'Purple', 'Blue', 'Green', 'Yellow', 'Orange']
n_colors = len(rainbow_colors)
grid = BlockGrid(41, 5, block_size=30, lines_on=False)
for i in range(100):
    for block in grid:
        color_name = rainbow_colors[(block.row + block.col + i) % n_colors]
        block.rgb = colors[color_name]
    grid.flash()
grid.show()

def inside_grid(ball_position, grid):
    return ball_position[0] >= 0 \
        and ball_position[1] >= 0 \
        and ball_position[0] <= grid.shape[0] - 1 \
        and ball_position[1] <= grid.shape[1] - 1

def move_monster(monster_position, grid):
    while True:
        move_directions = [(0,1), (1, 0), (-1, 0), (0, -1)] # try changing this!
        move = random.choice(move_directions)
        next_position = add_position(monster_position, move)
        if inside_grid(next_position, grid):
            break
    return next_position

def add_position(pos1, pos2):
    """ 
    Add a position and a move together:
    add_position( (2,3), (0,1) ) == (2,4)
    """
    return (pos1[0] + pos2[0], pos1[1] + pos2[1])

monster_position = (randint(1, grid.shape[0]), randint(1, grid.shape[1]))
grid = BlockGrid(41, 10, block_size=30, lines_on=True)
eaten_positions = []

# Try changing the colors!
monster_color = colors['DarkOrange']
grid_color = colors['Purple']
eaten_color = colors['White']

for i in range(100):
    # Add the monster position to the list of eaten positions
    eaten_positions.append(monster_position)
    monster_position = move_monster(monster_position, grid)
    for block in grid:
        block_coordinates = (block.col, block.row)
        if block_coordinates == monster_position:
            block.rgb = monster_color
        elif block_coordinates in eaten_positions:
            block.rgb = eaten_color
        else:
            block.rgb = grid_color
    grid.flash()
grid.show()