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

public class DragVideoPanel : MonoBehaviour, IDragHandler, IBeginDragHandler, IEndDragHandler
{
    private RectTransform canvasRect;
    public RectTransform transRect;
    private Vector2 localPos;
    private Vector2 offSet;
    public bool limit;
    private Vector2 anchoredPosition;

    private void Start()
    {
        canvasRect = GameObject.Find("Canvas").GetComponent<RectTransform>();       
        offSet = localPos = Vector3.zero;
        anchoredPosition = transRect.anchoredPosition;
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;//不是左键按下就不能拖拽                                                                       
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, eventData.position, canvasRect.GetComponent<Canvas>().worldCamera, out localPos))
        {
            offSet = localPos - new Vector2(transRect.localPosition.x, transRect.localPosition.y);
            InputManager.isDargUI = true;
            //transform.SetAsLastSibling();
        }
    }

    public void OnDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;//不是左键按下就不能拖拽                                                                       
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasRect, eventData.position, canvasRect.GetComponent<Canvas>().worldCamera, out localPos))
        {

            transRect.localPosition = localPos - offSet;
        }
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        if (eventData.button != PointerEventData.InputButton.Left) return;//不是左键按下就不能拖拽
        InputManager.isDargUI = false;
        if (limit)
        {
            //if (OutLimit())
            //{             
            //transRect.anchoredPosition = anchoredPosition;            
            // }
            OutLimit();
        }
    }

    void OutLimit()
    {
        Vector3 pos = transRect.localPosition;

        Vector3 minPosition = transRect.parent.GetComponent<RectTransform>().rect.min - transRect.rect.min;
        Vector3 maxPosition = transRect.parent.GetComponent<RectTransform>().rect.max - transRect.rect.max;

        pos.x = Mathf.Clamp(transRect.localPosition.x, minPosition.x - transRect.rect.width + 50f, maxPosition.x + transRect.rect.width - 50f);
        pos.y = Mathf.Clamp(transRect.localPosition.y, minPosition.y - transRect.rect.height + 100f, maxPosition.y + transRect.rect.height - 100f);

        transRect.localPosition = pos;
    }
}