//--------------------------------------------------------
//    [Author]:           玩个游戏
//    [  Date ]:           Monday, July 31, 2017
//--------------------------------------------------------
using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
using System;

    public class DragItem:MonoBehaviour,ICanvasRaycastFilter,IBeginDragHandler,IDragHandler,IEndDragHandler {

        [SerializeField]
        RectTransform m_Area;
        public RectTransform area { get { return m_Area; } }

        [SerializeField]
        bool m_RaycastTarget = true;
        public bool raycastTarget {
            get { return m_RaycastTarget; }
            private set { m_RaycastTarget = value; }
        }

        RectTransform m_RectTransform;
        public RectTransform rectTransform { get { return this.transform as RectTransform; } }

        public void OnBeginDrag(PointerEventData eventData) {
            raycastTarget = false;
            this.transform.position = UIUtility.ClampWorldPosition(area,eventData);
        }

        public void OnDrag(PointerEventData eventData) {
            this.transform.position = UIUtility.ClampWorldPosition(area,eventData);
        }

        public void OnEndDrag(PointerEventData eventData) {
            raycastTarget = true;
            if(eventData.pointerEnter == null) {
                return;
            }

            var container = eventData.pointerEnter.GetComponent<DragContainer>();
            if(container == null) {
                return;
            }

            var contain = UIUtility.RectTransformContain(eventData.pointerEnter.transform as RectTransform,rectTransform);
            if(contain) {
                rectTransform.position = eventData.pointerEnter.transform.position;
            }
        }

        public bool IsRaycastLocationValid(Vector2 sp,Camera eventCamera) {
            return raycastTarget;
        }
    }