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




/// <summary>
/// 数字选择器
/// </summary>
public class NumPicker : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
{
    public int maxNum;
    public int minNum;
    public int _itemNum = 5;
    [HideInInspector]
    /// <summary>
    /// 更新选择的目标值
    /// </summary>
    public float _updateLength;
    /// <summary>
    /// 子节点预制体
    /// </summary>
    public GameObject _itemObj;
    /// <summary>
    /// 子节点容器对象
    /// </summary>
    public Transform _itemParent;
    public Color normalColor;
    public int value;
    public Action<int> onValueChange;
    void Awake()
    {
        _itemObj.SetActive(false);
        _updateLength = _itemObj.GetComponent<RectTransform>().sizeDelta.y/2;
    }
    private void Start()
    {
       // Init(10);
    }
    /// <summary>
    /// 初始化数字选择器
    /// </summary>
    public void Init(int num, Action<int> onValueChange)
    {
        this.onValueChange = onValueChange;
        value = num;
        for (int i = 0; i < _itemNum; i++)
        {
            //计算真实位置
            int real_i = -(_itemNum / 2) + i;
            SpawnItem(real_i);
        }
        RefreshDateList();
    }
    /// <summary>
    /// 生成子对象
    /// </summary>
    /// <param name="real_i">真实位置</param>
    /// <returns></returns>
    GameObject SpawnItem(float real_i)
    {
        GameObject _item = Instantiate(_itemObj);
        _item.SetActive(true);
        _item.transform.SetParent(_itemParent);
        _item.transform.localScale = Vector3.one;
        _item.transform.localEulerAngles = Vector3.zero;
        _item.transform.localPosition = Vector3.zero;
        if (real_i != 0)
        {
            _item.GetComponent<Text>().color = normalColor;
           // _item.transform.eulerAngles += new Vector3(20 * Mathf.Abs(real_i), 0, 0);
            _item.GetComponent<RectTransform>().sizeDelta -= new Vector2(0, 80);
           // _item.GetComponent<Text>().fontSize -= 30;
            //_item.GetComponent<Text>().fontStyle = FontStyle.Normal;
        }
        return _item;
    }

    Vector3 oldDragPos;
    /// <summary>
    /// 当开始拖拽
    /// </summary>
    /// <param name="eventData"></param>
    public void OnBeginDrag(PointerEventData eventData)
    {
        oldDragPos = eventData.position;
    }

    public void OnDrag(PointerEventData eventData)
    {
        UpdateSelectDate(eventData);
    }

    public void OnEndDrag(PointerEventData eventData)
    {
        _itemParent.localPosition = Vector3.zero;
    }

    /// <summary>
    /// 更新选择的数字
    /// </summary>
    /// <param name="eventData"></param>
    void UpdateSelectDate(PointerEventData eventData)
    {
        //判断拖拽的长度是否大于目标值
        if (Mathf.Abs(eventData.position.y - oldDragPos.y) >= _updateLength)
        {
            int num;
            //判断加减
            if (eventData.position.y > oldDragPos.y)
            {
                //+
                num = (int)(Mathf.Abs(eventData.position.y - oldDragPos.y) / _updateLength);
            }
            else
            {
                //-
                num = -(int)(Mathf.Abs(eventData.position.y - oldDragPos.y) / _updateLength);
            }
            value += num;
           
            //判断是否属于时间段
            if (IsInRange(value))
            {
                oldDragPos = eventData.position;
                RefreshDateList();
            }
            else
            {
                value -= num;
                RefreshDateList();
            }
             onValueChange?.Invoke(value);
            _itemParent.localPosition = Vector3.zero;
          
        }
        else
        {
            _itemParent.localPosition = new Vector3(0, (eventData.position.y - oldDragPos.y), 0);
        }
    }

    /// <summary>
    /// 刷新时间列表
    /// </summary>
    public void RefreshDateList()
    {
        for (int i = 0; i < _itemNum; i++)
        {
            //计算真实位置
            int real_i = -(_itemNum / 2) + i;
           
            string str = "";
            if (IsInRange(value+ real_i))
            {
                int nowvalue=value+real_i;
                if(nowvalue<10)
                    str ="0"+nowvalue;
                else
                    str=nowvalue.ToString();
                
            }
            _itemParent.GetChild(i).GetComponent<Text>().text = str;
        }

    }
    public bool IsInRange(int value)
    {
        return value>=minNum &&value<=maxNum ;
    }
}