using DG.Tweening;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class SlideScrollView : MonoBehaviour, IBeginDragHandler, IEndDragHandler
{
    private RectTransform contentTrans;
    private float beginMousePositionX;
    private float endMousePositionX;
    private ScrollRect scrollRect;

    public int cellLength;
    public int spaceing;
    public int leftOffset;

    private float moveOneItemLength;
    private Vector3 currentContentLocalPos;//上一次的位置

    public int totalItemNum;
    private int currenIndex;
    private void Awake()
    {
        scrollRect = GetComponent<ScrollRect>();
        contentTrans = scrollRect.content;
        moveOneItemLength = cellLength + spaceing;
        currentContentLocalPos = contentTrans.localPosition;
        currenIndex = 1;
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        endMousePositionX = Input.mousePosition.x;
        float offSetX = 0;
        float moveDistance = 0;//当次需要滑动的距离
        offSetX = beginMousePositionX - endMousePositionX;


        if (offSetX > 0)//右滑
        {
            if (currenIndex >= totalItemNum)
            {
                return;
            }
            moveDistance = -moveOneItemLength;
            currenIndex++;
        }
        else//左滑
        {
            if (currenIndex <= 1)
            {
                return;
            }
            moveDistance = moveOneItemLength;
            currenIndex--;
        }

        DOTween.To(() => contentTrans.localPosition, lerpValue => contentTrans.localPosition = lerpValue, currentContentLocalPos + new Vector3(moveDistance, 0, 0), 0.5f).SetEase(Ease.InOutQuint);
        currentContentLocalPos += new Vector3(moveDistance, 0, 0);
    }

    public void OnBeginDrag(PointerEventData eventData)
    {
        beginMousePositionX = Input.mousePosition.x;
    }
}