using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class ToolDragSpawner : MonoBehaviour,
    IPointerDownHandler, IDragHandler, IPointerUpHandler
{
    public GameObject dragGhostPrefab;
    public Transform dragLayer;

    private GameObject ghost;
    private RectTransform ghostRect;

    private RectTransform selfRect;

    public void OnPointerDown(PointerEventData eventData)
    {
        // 创建影子
        ghost = Instantiate(dragGhostPrefab, dragLayer);

        // 同步图片
        Image src = GetComponent<Image>();
        Image dst = ghost.GetComponent<Image>();
        ghostRect = ghost.transform as RectTransform;
        selfRect=transform.GetComponent<RectTransform>();
        dst.sprite = src.sprite;
        SyncRectTransform(selfRect, ghostRect);
        ghost.transform.position = eventData.position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        if (ghost != null)
            ghost.transform.position = eventData.position;
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        // 抬起事件（重点）
        HandleDrop(eventData);

        Destroy(ghost);
    }

    void SyncRectTransform(RectTransform src, RectTransform dst)
    {
        dst.anchorMin = src.anchorMin;
        dst.anchorMax = src.anchorMax;
        dst.pivot = src.pivot;
        dst.sizeDelta = src.sizeDelta;
        dst.localScale = Vector3.one; // 防止父节点缩放干扰
    }

    void HandleDrop(PointerEventData eventData)
    {
        // UI 命中检测
        if (IsClickUI())
        {
            Debug.Log("在UI上抬起");
        }
        else
        {
            Debug.Log("拖拽到非UI区域");
            // 👉 在这里生成3D模型
        }
    }

    private bool IsClickUI()
    {
        PointerEventData eventData = new PointerEventData(EventSystem.current);
        eventData.position = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        List<RaycastResult> raycastResults = new List<RaycastResult>();
        EventSystem.current.RaycastAll(eventData, raycastResults);

        return raycastResults.Count > 0;
    }
}