using DG.Tweening;
using UnityEngine;
using UnityEngine.EventSystems;

/// <summary>
/// 按下缩小、抬起还原。
/// 只实现 IPointerDownHandler / IPointerUpHandler，不实现 IDragHandler 等拖动接口，
/// 所以挂在 ScrollRect 内的按钮上不会抢走 ScrollRect 的滑动。
/// </summary>
public class UIPressScale : MonoBehaviour, IPointerDownHandler, IPointerUpHandler
{
    [Tooltip("缩放目标，留空则缩放自身")]
    public Transform target;
    public float pressScale = 0.95f; // 按下时缩放比例
    public float duration = 0.1f;    // 缩放动画时长

    private Vector3 _standardScale;
    private bool _captured;
    private bool _isPressing;

    private Transform Target => target != null ? target : transform;

    public void OnPointerDown(PointerEventData eventData) => SetPressing(true);
    public void OnPointerUp(PointerEventData eventData) => SetPressing(false);

    private void SetPressing(bool pressing)
    {
        if (_isPressing == pressing) return;
        _isPressing = pressing;

        var t = Target;
        if (!_captured)
        {
            _standardScale = t.localScale; // 首次使用时记录原缩放
            _captured = true;
        }
        t.DOKill();
        t.DOScale(pressing ? _standardScale * pressScale : _standardScale, duration)
            .SetEase(Ease.OutQuad);
    }

    // 被隐藏时立即还原，避免按下瞬间目标被关掉而停在缩小状态
    private void OnDisable()
    {
        _isPressing = false;
        if (!_captured) return;
        Target.DOKill();
        Target.localScale = _standardScale;
    }
}