using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
using UnityEngine.UI;
public class DragHandeler : MonoBehaviour,IDragHandler,IBeginDragHandler,IEndDragHandler {
	public static GameObject itemBeingDragged;

	Vector3 startPosition;
	Transform startParent;
	//canvasはDrag中に選択肢が他のUIの背後に回らないために使う
	Transform canvas;
	#region IBeginDragHandler implementation

	public void OnBeginDrag(PointerEventData eventData){
		itemBeingDragged = gameObject;
		startPosition = transform.position;
		startParent = transform.parent;
		GetComponent<CanvasGroup> ().blocksRaycasts = false;

		canvas = GameObject.FindGameObjectWithTag("UI Canvas").transform;
		transform.parent = canvas;
	}
	#endregion

	#region IDragHandler implementation
	public void OnDrag(PointerEventData eventData)
	{
		transform.position = Input.mousePosition;
	}
	#endregion

	#region IEndDragHandler implementation
	public void OnEndDrag(PointerEventData eventData)
	{

		itemBeingDragged = null;

		GetComponent<CanvasGroup> ().blocksRaycasts = true;
		if (transform.parent == canvas) {
			transform.position = startPosition;
		}
	}
	#endregion
}