using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UIElements;
namespace BITKit.UX
{
    public class UXDrag : UXElement<VisualElement>
    {
        Vector3 m_IconStartPosition;
        Vector3 m_PointerStartPosition;
        bool isDraging;
        public override void OnStart()
        {
            base.OnStart();
            // listen for LMB down
            visualElement.RegisterCallback<PointerDownEvent>(PointerDownEventHandler);

            // listen for mouse movement and LMB up
            visualElement.RegisterCallback<PointerMoveEvent>(PointerMoveEventHandler);
            visualElement.RegisterCallback<PointerUpEvent>(PointerUpEventHandler);
        }
        protected virtual void PointerMoveEventHandler(PointerMoveEvent evt)
        {
            if (isDraging && visualElement.HasPointerCapture(evt.pointerId))
            {
                float newX = m_IconStartPosition.x + (evt.position.x - m_PointerStartPosition.x);
                float newY = m_IconStartPosition.y + (evt.position.y - m_PointerStartPosition.y);

                var delta = new Vector2(newX, newY);
                delta = GetProcessDelta(delta);
                visualElement.transform.position = delta;
                OnDelta(delta);
            }
        }

        protected virtual void PointerDownEventHandler(PointerDownEvent evt)
        {
            // set the icon and pointer starting positions
            m_IconStartPosition = visualElement.transform.position;
            m_PointerStartPosition = evt.position;

            visualElement.CapturePointer(evt.pointerId);

            isDraging = true;
        }

        protected virtual void PointerUpEventHandler(PointerUpEvent evt)
        {
            isDraging = false;

            visualElement.ReleasePointer(evt.pointerId);
        }

        protected virtual Vector2 GetProcessDelta(Vector2 delta)
        {
            return delta;
        }
        protected virtual void OnDelta(Vector2 delta)
        {

        }
    }
}