# ========== 功能函數 ==========
def set_cycle_rule(rule_str):
    global N, rule_text
    default = list(range(N))
    parts = [s.strip() for s in rule_str.split(".") if s.strip() != ""]
    if len(parts) == 0:
        # 空或全是空白 -> 設為預設
        rule_text.value = ".".join(map(str, default))
        return default
    try:
        lst = [int(x) for x in parts]
    except Exception:
        # 解析非整數 -> 設為預設
        rule_text.value = ".".join(map(str, default))
        return default
    # 檢查每個數值是否在 0..N-1 範圍內
    if any((v < 0 ) for v in lst):
        rule_text.value = ".".join(map(str, default))
        return default
    # 成功解析且都在合法範圍
    return lst

def cycle_value(val):
    """根據 cycle_rule 回傳下一個值"""
    if val not in cycle_rule:
        return cycle_rule[0]
    idx = cycle_rule.index(val)
    return cycle_rule[(idx + 1) % len(cycle_rule)]

def apply_button(r, c):
    """按下按鈕 A[r,c]，變色四個相鄰的 B 方格"""
    global steps, board
    r0, c0 = r - 1, c - 1
    if r0 + 1 >= N or c0 + 1 >= N:
        return
    for dr in [0, 1]:
        for dc in [0, 1]:
            rr, cc = r0 + dr, c0 + dc
            board[rr, cc] = cycle_value(board[rr, cc])
    steps += 1
    redraw_board()

def reset_board(_=None):
    """重設棋盤"""
    global board, steps
    board = initial_board.copy()
    steps = 0
    redraw_board()

def generate_initial_board():
    """生成 NxN 棋盤，黑格=0，白格=white_value"""
    b = np.zeros((N, N), dtype=int)
    for r in range(N):
        for c in range(N):
            if (r + c) % 2 == 0:
                b[r, c] = black_value
            else:
                b[r, c] = white_value
    return b

def draw_board():
    """畫出棋盤 + 按鈕"""
    fig, ax = plt.subplots(figsize=(5, 5))
    ax.set_xlim(0, N)
    ax.set_ylim(0, N)
    ax.set_xticks([])
    ax.set_yticks([])
    ax.set_aspect('equal')
    ax.invert_yaxis()

    # 畫格子 (顯示數字)
    for r in range(N):
        for c in range(N):
            ax.add_patch(plt.Rectangle((c, r), 1, 1, color="white", ec='black', linewidth=2))
            ax.text(c + 0.5, r + 0.5, str(board[r, c]), ha='center', va='center', fontsize=12, color='black')

    # 畫綠色按鈕 A[r,c]
    for r, c in valid_buttons:
        cx, cy = c, r
        circle = plt.Circle((cx, cy), 0.3, color=button_color)
        ax.add_patch(circle)
        ax.text(cx, cy, f'A{r},{c}', ha='center', va='center', fontsize=8, color='red')

    # 畫步數
    ax.text(N/2, -0.3, f"{steps}", ha='center', va='center', fontsize=14, color='black')
    plt.show()

def redraw_board():
    """只更新棋盤，不清除輸入框"""
    with board_output:
        clear_output(wait=True)
        draw_board()

def update_board(_=None):
    """讀取輸入框 → 更新棋盤"""
    global N, cycle_rule, white_value, steps, board, initial_board, valid_buttons, button_grid

    # 更新參數
    try:
        N = int(N_text.value)
    except:
        N = 3

    cycle_rule = set_cycle_rule(rule_text.value)

    try:
        white_value = int(white_text.value)
    except:
        white_value = 1

    steps = 0
    board = generate_initial_board()
    initial_board = board.copy()
    valid_buttons = [(r, c) for r in range(1, N) for c in range(1, N)]

    # 建立互動按鈕
    button_widgets = []
    for (r, c) in valid_buttons:
        def make_handler(r=r, c=c):
            def on_click(b):
                apply_button(r, c)
            return on_click
        b = widgets.Button(description=f'A{r},{c}', layout=widgets.Layout(width='70px', height='30px'))
        b.on_click(make_handler(r, c))
        button_widgets.append(b)

    # 更新互動按鈕區
    button_grid.children = button_widgets
    button_grid.layout = widgets.Layout(grid_template_columns=f"repeat({N-1}, 80px)")

    redraw_board()