using UnityEngine;
using UnityEngine.UI;

[RequireComponent(typeof(Toggle))]
public class ExclusiveToggleVisual : MonoBehaviour
{
    [Header("選中時圖片")]
    [SerializeField] private Sprite onBackground;
    [SerializeField] private Sprite onCheckmark;

    [Header("未選中時圖片（留空 = 原始圖）")]
    [SerializeField] private Sprite offBackground;
    [SerializeField] private Sprite offCheckmark;

    private Toggle toggle;
    private Image bgImage;
    private Image checkImage;
    private Sprite origBg, origCheck;

    private void Awake()
    {
        toggle = GetComponent<Toggle>();
        bgImage = toggle.targetGraphic as Image;
        checkImage = toggle.graphic as Image;

        // 儲存原始圖片（供 off 狀態使用）
        if (bgImage) origBg = bgImage.sprite;
        if (checkImage) origCheck = checkImage.sprite;

        // 關閉 UI 焦點干擾
        toggle.transition = Selectable.Transition.None;
        toggle.navigation = new Navigation { mode = Navigation.Mode.None };

        // 初始 + 監聽
        SyncVisual();
        toggle.onValueChanged.AddListener(_ => SyncVisual());
    }

    private void SyncVisual()
    {
        bool isOn = toggle.isOn;

        // 背景圖
        if (bgImage && onBackground)
            bgImage.sprite = isOn ? onBackground : (offBackground ?? origBg);

        // Checkmark 圖（僅在選中時顯示）
        if (checkImage)
        {
            if (onCheckmark)
                checkImage.sprite = isOn ? onCheckmark : (offCheckmark ?? origCheck);
            checkImage.enabled = isOn;
        }
    }

    // 外部可強制刷新（如動態換圖）
    public void Refresh() => SyncVisual();
}