using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System;
/// <summary>
/// IBeginDragHandler开始拖动接口,IEndDragHandler结束拖动按钮
/// </summary>
public class ScrollDemo : MonoBehaviour,IBeginDragHandler,IEndDragHandler {
    [SerializeField]
    List<Toggle> toggles;

    public ScrollRect scrollRect;

    //目标位置
    public float targetPos=0;

    //public InputField inputField;

    //每页滚动区域定位
    public float[] posArr = new float[] { 0, 0.333f, 0.666f, 1f };

    //是否在被拖动
    public bool isDrag = false;

    public int curPageIndex = 0;

    // Use this for initialization
    void Start () {
        scrollRect = this.GetComponent<ScrollRect>();
        //获取所有子对象中的所有Toggle组件
        toggles = new List<Toggle>();
        this.GetComponentsInChildren<Toggle>(toggles);
        //给每一个toggle添加点击事件
        foreach (Toggle item in toggles)
        {
            item.onValueChanged.AddListener(
                delegate (bool flag)
                {
                    ToggleClicked(item, flag);
                }
                );
        }
        scrollRect.horizontalNormalizedPosition = 0;
    }
    /// <summary>
    /// 单选按钮被点击时触发监听
    /// </summary>
    /// <param name="toggle">被点击按钮</param>
    /// <param name="flag">是否被点击</param>
    void ToggleClicked(Toggle toggle,bool flag)
    {
        if (flag)
        {

            //把名称中的p字符替换成空，只留下数字，然后转成int类型,做下表
            int index = int.Parse(toggle.name.Replace("p",""));
            curPageIndex = index;
            targetPos = posArr[index];
            //更新滚动区域
            //scrollRect.horizontalNormalizedPosition = posArr[index];


        }
    }

	// Update is called once per frame
	void Update () {
        //判断是否在拖动过程
        if (!isDrag)
        {
            scrollRect.horizontalNormalizedPosition = Mathf.Lerp(scrollRect.horizontalNormalizedPosition, targetPos, Time.deltaTime * 5);
        }

	}

    //开始拖动函数
    public void OnBeginDrag(PointerEventData eventData)
    {
        isDrag = true;
    }
    //结束拖动函数
    public void OnEndDrag(PointerEventData eventData)
    {
        isDrag = false;

        ////当前位置
        //float curPos = scrollRect.horizontalNormalizedPosition;
        ////误差
        //float  minOffset = 0.5f;
        ////当前最近项索引
        //int posIndex = 0;

        ////通过比较，得到最近页的位置
        //for (int i = 0; i < posArr.Length;i++)
        //{
        //    //记录临时差
        //    float tmp=Mathf.Abs(curPos - posArr[i]);
        //    if (tmp<minOffset)
        //    {
        //        minOffset = tmp;
        //        //存储下当前索引
        //        posIndex = i;
        //    }
        //}

        ////更新目标位置
        //targetPos = posArr[posIndex];
        //toggles[posIndex].isOn = true;







        /********
         * 第二中方法
         **************/

        float curPos = scrollRect.horizontalNormalizedPosition;
        //根据当前和原来位置差，是正还是负，判断向左向右滑
        if (Mathf.Abs(curPos - targetPos) < 0.07f) return;
        if (curPos - targetPos > 0)
        {
            //如果向右滑，将页码+1
            curPageIndex = curPageIndex + 1 >= posArr.Length - 1 ? posArr.Length - 1 : curPageIndex + 1;
        }
        else
        {
            //向左滑，页码-1
            curPageIndex = curPageIndex - 1 <= 0 ? 0 : curPageIndex - 1;
        }

        targetPos = posArr[curPageIndex];
        toggles[curPageIndex].isOn = true;
    }
}