using UnityEngine;
using UnityEngine.EventSystems;

namespace XED.UI
{
    public class UI_WindowDrag : UnityEngine.MonoBehaviour, IBeginDragHandler, IEndDragHandler, IDragHandler, IPointerDownHandler
    {
        Canvas canvas;
        Vector3 originalPos;
        Vector3 dragOffset;
        // Start is called before the first frame update
        void Awake()
        {
            canvas = GetComponentInParent<Canvas>();
        }

        public void OnBeginDrag(PointerEventData eventData)
        {
            originalPos = transform.localPosition;
            RectTransformUtility.ScreenPointToWorldPointInRectangle(
                canvas.transform as RectTransform,
                eventData.position,
                eventData.pressEventCamera,
                out var worldMousePos
            );
            dragOffset = transform.position - worldMousePos;
        }
        public void OnDrag(PointerEventData eventData)
        {
            if (canvas == null) return;
            RectTransformUtility.ScreenPointToWorldPointInRectangle(
                canvas.transform as RectTransform,
                eventData.position,
                eventData.pressEventCamera,
                out var worldMousePos
            );
            transform.position = worldMousePos + dragOffset;
        }
        public void OnEndDrag(PointerEventData eventData)
        {

        }
        public void OnPointerDown(PointerEventData eventData)
        {
            transform.SetAsLastSibling();
        }
    }
}