using UnityEngine;
using System.Collections;
using UnityEngine.EventSystems;
using System;
using UnityEngine.UI;

public class Draggable : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
{

    public Vector2 dragOffset = new Vector2(0f, 0f);
    public Transform parentToReturnTo = null;
    public Transform placeHolderParent = null;
    GameObject placeHolder = null;

    public void OnBeginDrag(PointerEventData eventData)
    {
        //  Debug.Log("OnBeginDrag");

        placeHolder = new GameObject();
        placeHolder.transform.SetParent(this.transform.parent);
        LayoutElement le = placeHolder.AddComponent<LayoutElement>();
        le.preferredWidth = this.GetComponent<LayoutElement>().preferredWidth;
        le.preferredHeight = this.GetComponent<LayoutElement>().preferredHeight;
        le.flexibleHeight = 0;
        le.flexibleWidth = 0;

        placeHolder.transform.SetSiblingIndex(this.transform.GetSiblingIndex());


        parentToReturnTo = this.transform.parent;
        placeHolderParent = parentToReturnTo;
        this.transform.SetParent(this.transform.parent.parent);

        GetComponent<CanvasGroup>().blocksRaycasts = false;

        dragOffset = eventData.position - (Vector2)this.transform.position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        //Debug.Log("OnDrag");

        this.transform.position = eventData.position;

        if (placeHolder.transform.parent != placeHolderParent )
        {
            placeHolder.transform.SetParent(placeHolderParent);
        }


        int newSiblingIndex = placeHolderParent.childCount ;

        for(int i =0; i < placeHolderParent.childCount; i++)
        {
            if(this.transform.position.x < placeHolderParent.GetChild(i).position.x)
            {
                newSiblingIndex = i;
                if(placeHolder.transform.GetSiblingIndex()< newSiblingIndex)
                {
                    newSiblingIndex--;
                }


                break;
            }
        }


        placeHolder.transform.SetSiblingIndex(newSiblingIndex);

        this.transform.position = eventData.position - dragOffset;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        //Debug.Log("OnEndDrag");
        Debug.Log("name: " + parentToReturnTo.name);

        if (!parentToReturnTo.name.Equals("Tabletop opponent")) {
            this.transform.SetParent(parentToReturnTo);
            this.transform.SetSiblingIndex(placeHolder.transform.GetSiblingIndex());
        } else
        {
            this.transform.SetParent(placeHolderParent);
            this.transform.SetSiblingIndex(placeHolder.transform.GetSiblingIndex());
        }
        GetComponent<CanvasGroup>().blocksRaycasts = true;

        Destroy(placeHolder);
    }
}