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

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

    public Transform parentToReturnTo = null;
    public Transform placeholderParent = null;

    GameObject placeholder = null;

    public enum Table { PLAYER, ENEMY }
    public Table typeOfItem = Table.PLAYER;

    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.flexibleWidth = 0;
        le.flexibleHeight = 0;

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

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

        GetComponent<CanvasGroup>().blocksRaycasts = false;
    }

    public void OnDrag(PointerEventData eventData) {

        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);

    }

    public void OnEndDrag(PointerEventData eventData) {
        Debug.Log ("OnEndDrag");
        this.transform.SetParent( parentToReturnTo );
        this.transform.SetSiblingIndex( placeholder.transform.GetSiblingIndex() );
        GetComponent<CanvasGroup>().blocksRaycasts = true;

        Destroy(placeholder);
    }

}