//**********************************************//
//作者:#何健#
//日期:#2016.10.09#
//简述:#ScrollView优化，使用一定数量子项实现大量数据循环加载#
//*********************************************//
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System.Text;

namespace Thousandto.Plugins.Common
{
    /// <summary>
    /// 类BackPackItem说明
    /// </summary>
    [RequireComponent(typeof(UIGrid))]
    public class UILoopScrollViewBase : MonoCacheBase
    {
        #region Members  

        /// <summary>  
        /// 存储物件列表  
        /// </summary>  
        private List<GameObject> m_itemList = new List<GameObject>();

        /// <summary>  
        /// 起始下标  
        /// </summary>  
        private int _startIndex = 1;

        /// <summary>  
        /// 最大长度  
        /// </summary>  
        private int _maxCount;

        /// <summary>  
        /// 父ScrollView  
        /// </summary>  
        public UIScrollView _scrollView;

        /// <summary>  
        /// grid  
        /// </summary>  
        public UIGrid _grid;       
        /// <summary>  
        /// templateItem 
        /// </summary>  
        public GameObject _templateItem;
        /// <summary>  
        /// 物件刷新代理事件  
        /// </summary>  
        /// <param name="go"></param>  
        public delegate void OnItemChange(Transform obj, string name, bool isClear);
        private OnItemChange m_pItemChangeCallBack;

        private Vector2 _scrollViewPos = new Vector2(0, 0);
        private Vector3 lastPos;
        private bool _isRecodePos = false;
        #endregion

        #region 回调处理
        /// <summary>  
        /// 设置代理  
        /// </summary>  
        /// <param name="_onItemChange"></param>  
        public void SetDelegate(OnItemChange _onItemChange)
        {
            m_pItemChangeCallBack = _onItemChange;
        }

        /// <summary>  
        /// 物件刷新代理事件  
        /// </summary>  
        /// <param name="go"></param>  
        private void OnItemChangeMsg(Transform obj,string name, bool isClear)
        {
            if (m_pItemChangeCallBack != null)
            {
                m_pItemChangeCallBack(obj, name, isClear);
            }
        }
        #endregion

        /// <summary>  
        /// 初始化表  
        /// </summary>  
        public void Init(int maxCount, GameObject templateItem = null, int waitCount = 1, bool isResetScrool = true)
        {
            _isRecodePos = false;
            _maxCount = maxCount;
            if (isResetScrool)
            {
                // 如果传入有控件则以传入的为模板如果没有则查找grid下面第一个子控件
                _grid = transform.GetComponent<UIGrid>();
                _scrollView = transform.parent.GetComponent<UIScrollView>();
                _grid.gameObject.SetActive(true);
                var _num = _maxCount % _grid.maxPerLine;
                if (_num != 0)
                {
                    _maxCount = _maxCount + _grid.maxPerLine - _num;
                }
                if (templateItem)
                {
                    _templateItem = templateItem;
                }
                else
                {
                    _templateItem = _grid.transform.GetChild(0).gameObject;
                }
                try
                {
                    StartCoroutine(Respositon(waitCount));
                }
                finally
                {
                }
            }
            else
            {
                //当前显示出来的第一个格子，在grid数据中的index  
                var childCount = _grid.transform.childCount;
                int index = Mathf.FloorToInt((_maxCount - childCount) / _grid.maxPerLine);

                for (int i = index * _grid.maxPerLine; i < childCount + index * _grid.maxPerLine; i++)
                {
                    if (i >= _maxCount)
                        return;
                    FillItem(i - index * _grid.maxPerLine + _startIndex, i + _startIndex, i == childCount + index * _grid.maxPerLine - 1);
                }
            }
        }
        private IEnumerator Respositon(int waitCount = 0)
        {
            InitGird();
            _grid.Reposition();
            yield return waitCount;
            _scrollView.ResetPosition();
            _isRecodePos = true;
        }
        private void InitGird()
        {
            m_itemList.Clear();
            // 将现有的子项添加到容器  
            for (int i = 0; i < _grid.transform.childCount; i++)
            {
                GameObject go = _grid.transform.GetChild(i).gameObject;
                //go.SetActive(false);
                m_itemList.Add(go);
            }
            
            int fillCount = 0; //当前scrollView被填满的格子数  
            int lastIndex = 0; //上次显示出来的第一个格子，在grid数据中的index  
            var _indexDis = 0f;
            UIPanel panel = _scrollView.GetComponent<UIPanel>();
            if (_scrollView.movement == UIScrollView.Movement.Vertical)
            {
                fillCount = Mathf.CeilToInt(panel.height / _grid.cellHeight);
                fillCount = fillCount * _grid.maxPerLine;
                _indexDis = _grid.cellHeight;
            }
            else if (_scrollView.movement == UIScrollView.Movement.Horizontal)
            {
                fillCount = Mathf.CeilToInt(panel.width / _grid.cellWidth);
                _indexDis = _grid.cellWidth;
            }
            //if (_maxCount < fillCount + _grid.maxPerLine)
            //    _maxCount = fillCount + _grid.maxPerLine;
            int childCount = _maxCount;

            // 如果item数量大于填满显示面板的数量做优化  
            if (childCount > fillCount + _grid.maxPerLine)
            {
                childCount = fillCount + _grid.maxPerLine;

                // 拖拽刷新面板  
                panel.onClipMove = (uiPanel) => {
                    Vector3 delata = lastPos - panel.transform.localPosition;
                    float distance = System.Math.Abs(delata.y) > 0.5 ? delata.y : delata.x;

                    // 满的时候向上滑不管它  
                    if ((distance > 0 && _scrollView.movement == UIScrollView.Movement.Vertical) || (distance < 0 && _scrollView.movement == UIScrollView.Movement.Horizontal))
                        return;
                    if (distance < 0)
                        distance = -distance;
                    //当前显示出来的第一个格子，在grid数据中的index  
                    int index = Mathf.FloorToInt(distance / _indexDis);

                    // 拖拽不满一个单元格  
                    if (index == lastIndex) return;
                    // 拉到底了  
                    if (index + childCount > _maxCount) {
                        for (int i = 1; i <= _grid.transform.childCount; i++)
                        {
                            if (i >= _maxCount)
                                return;
                            var _newKey = _maxCount >= _grid.transform.childCount ? _maxCount - _grid.transform.childCount + i : i;
                            FillItem(i, _newKey, i == _grid.transform.childCount);
                        }
                        return;
                    }

                    lastIndex = index;

                    // 重刷  
                    if ((index - 1) * _grid.maxPerLine + childCount < _maxCount)
                    {
                        for (int i = index * _grid.maxPerLine; i < childCount + index * _grid.maxPerLine; i++)
                        {
                            if (i >= _maxCount)
                                return;
                            FillItem(i - index * _grid.maxPerLine + _startIndex, i + _startIndex, i == childCount + index * _grid.maxPerLine - 1);
                        }
                    }
                };
            }
            _scrollView.onStoppedMoving = OnDragFinished;

            // 添加能填满UI数量的子项
            var allCount = fillCount + _grid.maxPerLine;
            for (int i = 0; i < allCount; i++)
            {
                bool isClear = false;
                if (i == 0)
                {
                    isClear = true;
                }

                if (i >= _maxCount)
                {
                    break;
                }
                GameObject go = null;
                if (i < m_itemList.Count)
                {
                    go = m_itemList[i];
                }
                else
                {
                    go = NGUITools.AddChild(_grid.gameObject, _templateItem);
                    m_itemList.Add(go);
                }
                go.SetActive(true);
                FillItem(i + _startIndex, i + _startIndex, isClear);
                //if (m_itemList.Count > i)
                //{
                //    FillItem(i + _startIndex, i + _startIndex, isClear);
                //    continue;
                //}
                //GameObject go = NGUITools.AddChild(_grid.gameObject, _templateItem);
                //go.SetActive(true);
                //m_itemList.Add(go);
                //FillItem(i + _startIndex, i + _startIndex, isClear);
            }
            for (int i = allCount; i < m_itemList.Count; i++)
            {
                m_itemList[i].SetActive(false);
            }
            lastPos = panel.transform.localPosition;
        }
        public void OnDragFinished()
        {
            if (_scrollView.movement == UIScrollView.Movement.Vertical)
            {
                int indexY = (int)_scrollViewPos.y;
                if (indexY + 10 > (int)_scrollView.transform.localPosition.y && indexY - 10 < (int)_scrollView.transform.localPosition.y)
                {
                    for (int i = 0; i < _grid.transform.childCount; i++)
                    {
                        if (i >= _maxCount)
                            return;
                        FillItem(i + _startIndex, i + _startIndex, i == _grid.transform.childCount - 1);
                    }
                }
            }
            else if(_scrollView.movement == UIScrollView.Movement.Horizontal)
            {
                int indexY = (int)_scrollViewPos.x;
                if (indexY + 10 > (int)_scrollView.transform.localPosition.x && indexY - 10 < (int)_scrollView.transform.localPosition.x)
                {
                    for (int i = 0; i < _grid.transform.childCount; i++)
                    {
                        if (i >= _maxCount)
                            return;
                        FillItem(i + _startIndex, i + _startIndex, i == _grid.transform.childCount - 1);
                    }
                }
            }
        }
        // 修改子项位置 
        public void FillItem(int oldIndex, int index, bool isClear)
        {
            //Debug.Log("-----oldIndex=" + oldIndex + ",index = " + index + ", itemListCount=" + m_itemList.Count);
            int iListIndex = oldIndex - _startIndex;
            if (m_itemList.Count <= iListIndex)
                return;
            string oldKey = m_itemList[iListIndex].name;
            string newKey = index.ToString();
            m_itemList[iListIndex].name = newKey;
            if (_scrollView.movement == UIScrollView.Movement.Horizontal)// 如果是水平滑动，则只有一排
            {
                m_itemList[iListIndex].transform.localPosition = new Vector3(_grid.cellWidth * (index - 1), 0, 0);
            }
            else if (_scrollView.movement == UIScrollView.Movement.Vertical) // 纵向滑动时有可能有多列
            {
                int count = index / _grid.maxPerLine;
                int countLess = index % _grid.maxPerLine;
                if(countLess == 0)
                {
                    countLess = _grid.maxPerLine - _startIndex;
                    if(_startIndex != 0)
                    {
                        count -= 1;
                    }
                }
                else
                {
                    countLess -= _startIndex;
                }
                m_itemList[iListIndex].transform.localPosition = new Vector3(countLess * _grid.cellWidth, -_grid.cellHeight * count, 0);
                m_itemList[iListIndex].gameObject.SetActive(true);
            }

            OnItemChangeMsg(m_itemList[iListIndex].transform, newKey, isClear);
        }

        // 修改最大格子数
        public void OnSetMaxIndex(int max)
        {
            _maxCount = max;
            if(_grid != null)
            {
                var _num = _maxCount % _grid.maxPerLine;
                if (_num != 0)
                {
                    _maxCount = _maxCount - _grid.maxPerLine + _num;
                }
            }
        }

        // 修改最大格子数
        public int OnGetMaxIndex()
        {
            return _maxCount;
        }

        //重置lastpos
        public void ResetPos()
        {
            lastPos = _scrollView.GetComponent<UIPanel>().transform.localPosition;
        }

        private void Update()
        {
            if (_isRecodePos)
            {
                _scrollViewPos = _scrollView.transform.localPosition;
                ResetPos();
                _isRecodePos = false;
            }
        }
    }
}