using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

namespace BF
{
    public class BFScrollRectMultSize : BFScrollRectBase
    {
        public BFCell bfCell;
        public float spacing;
        public float topRecoveryOffset;
        public float downRecoveryOffset;
        public BFUIDirection direction;
        public bool reverse = false;

        Stack<BFCell> cellPool = new Stack<BFCell>();
        List<BFCell> activeCells = new List<BFCell>();

        int instantiateCount = 0;
        int totalCount = 0;

        void Awake()
        {
            if (bfCell.gameObject.activeSelf)
            {
                bfCell.gameObject.SetActive(false);
            }
        }

        public override void RefillCells(int totalCount, int targetIndex)
        {
            this.totalCount = totalCount;
            if (activeCells.Count != 0)
            {
                while (activeCells.Count != 0)
                {
                    Pool(activeCells[0]);
                }
                UnityScrollRect.StopMovement();
            }
            ContentTrans.anchoredPosition = Vector2.zero;
            ContentTrans.sizeDelta = direction == BFUIDirection.Vertical ?
                new Vector2(ContentTrans.sizeDelta.x, 0) : new Vector2(0, ContentTrans.sizeDelta.y);
            TryFullFill();
        }

        public override void SetTotalCount(int totalCount)
        {
            this.totalCount = totalCount;
            if (totalCount < activeCells.Count)
            {
                for (int i = activeCells.Count - 1; i > totalCount - 1; i--)
                {
                    Pool(activeCells[i]);
                }
            }
        }

        public override void RefreshAll()
        {
            int count = activeCells.Count;
            for (int i = 0; i < count; i++)
            {
                var cell = activeCells[i];
                var lastSize = direction == BFUIDirection.Vertical ? cell.Height + spacing : cell.Width + spacing;
                RefreshAction?.Invoke(cell.dataIndex, cell.objIndex);
                var size = direction == BFUIDirection.Vertical ? cell.Height + spacing : cell.Width + spacing;
                var sizeOffset = size - lastSize;
                for (int j = i + 1; j < count; j++)
                {
                    if(direction == BFUIDirection.Vertical)
                    {
                        activeCells[j].AnchoredPosition = new Vector2(activeCells[j].AnchoredPosition.x, activeCells[j].AnchoredPosition.y - sizeOffset);
                    }
                    else
                    {
                        activeCells[j].AnchoredPosition = new Vector2(activeCells[j].AnchoredPosition.x - sizeOffset, activeCells[j].AnchoredPosition.y);
                    }
                }

                if(direction == BFUIDirection.Vertical)
                {
                    ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, ContentTrans.sizeDelta.y + sizeOffset);
                }
                else
                {
                    ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, ContentTrans.sizeDelta.x + sizeOffset);
                }
            }
        }

        public override void SetSelected(int index)
        {
            selectedIndex = index;
            int count = activeCells.Count;
            for (int i = 0; i < count; i++)
            {
                var cell = activeCells[i];
                Selected?.Invoke(cell.dataIndex == index, cell.objIndex);
            }
        }

        public override void ClearCells()
        {
            while (activeCells.Count != 0)
            {
                Pool(activeCells[0]);
            }
            ContentTrans.anchoredPosition = Vector2.zero;
            ContentTrans.sizeDelta = direction == BFUIDirection.Vertical ?
                new Vector2(ContentTrans.sizeDelta.x, 0) : new Vector2(0, ContentTrans.sizeDelta.y);
        }

        public override void AnchoredPositionChange()
        {

        }

        protected override void TryFullFill()
        {
            int i = 0;
            while (CheckBorder() && i < totalCount)
            {
                i++;
            }
        }

        bool CheckBorder()
        {
            if (activeCells.Count == 0)
            {
                TryStartAdd();
                return false;
            }

            var cell = activeCells[0];
            if(direction == BFUIDirection.Vertical)
            {
                if(reverse)
                {
                    var delta = cell.AnchoredPosition.y + ContentTrans.anchoredPosition.y;
                    if (delta > 0 - topRecoveryOffset && TryAddUp())
                    {
                        return true;
                    }
                }
                else
                {
                    var delta = cell.AnchoredPosition.y + ContentTrans.anchoredPosition.y;
                    if (delta < 0 + topRecoveryOffset && TryAddUp())
                    {
                        return true;
                    }
                }
            }
            else
            {
                if(reverse)
                {
                    var delta = cell.AnchoredPosition.x + ContentTrans.anchoredPosition.x;
                    if (delta < 0 + topRecoveryOffset && TryAddUp())
                    {
                        return true;
                    }
                }
                else
                {
                    var delta = cell.AnchoredPosition.x + ContentTrans.anchoredPosition.x;
                    if (delta > 0 - topRecoveryOffset && TryAddUp())
                    {
                        return true;
                    }
                }
            }

            cell = activeCells[activeCells.Count - 1];
            if(direction == BFUIDirection.Vertical)
            {
                if(reverse)
                {
                    var delta = cell.AnchoredPosition.y + cell.Height + spacing + ContentTrans.anchoredPosition.y;
                    if (delta < ViewPortTrans.sizeDelta.y + downRecoveryOffset && TryAddDown())
                    {
                        return true;
                    }
                }
                else
                {
                    var delta = cell.AnchoredPosition.y - cell.Height - spacing + ContentTrans.anchoredPosition.y;
                    if (delta > -(ViewPortTrans.sizeDelta.y + downRecoveryOffset) && TryAddDown())
                    {
                        return true;
                    }
                }
            }
            else
            {
                if(reverse)
                {
                    var delta = cell.AnchoredPosition.x - cell.Width - spacing + ContentTrans.anchoredPosition.x;
                    if (delta > -(ViewPortTrans.sizeDelta.x + downRecoveryOffset) && TryAddDown())
                    {
                        return true;
                    }
                }
                else
                {
                    var delta = cell.AnchoredPosition.x + cell.Width + spacing + ContentTrans.anchoredPosition.x;
                    if (delta < ViewPortTrans.sizeDelta.x + downRecoveryOffset && TryAddDown())
                    {
                        return true;
                    }
                }
            }

            if (activeCells.Count <= 1)
            {
                return false;
            }

            if (NeedCull(activeCells[0]))
            {
                Pool(activeCells[0]);
                return true;
            }

            if (NeedCull(activeCells[activeCells.Count - 1]))
            {
                Pool(activeCells[activeCells.Count - 1]);
                return true;
            }

            return false;
        }

        void TryStartAdd()
        {
            if (totalCount == 0)
            {
                return;
            }
            var cell = GetCell();
            cell.dataIndex = 1;
            cell.name = StringConst.GetScrollRectCellName(0);
            cell.gameObject.SetActive(true);
            RefreshAction?.Invoke(cell.dataIndex, cell.objIndex);
            cell.CachedRectTransform.anchoredPosition = Vector2.zero;
            if (direction == BFUIDirection.Vertical)
            {
                ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, ContentTrans.sizeDelta.y + cell.Height + spacing);
            }
            else
            {
                ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, ContentTrans.sizeDelta.x + cell.Width + spacing);
            }
            activeCells.Add(cell);

        }

        bool TryAddDown()
        {
            var downCell = activeCells[activeCells.Count - 1];
            var downIndex = downCell.dataIndex;
            if (downIndex == totalCount)
            {
                return false;
            }

            var cell = GetCell();
            cell.dataIndex = downIndex + 1;
            cell.name = StringConst.GetScrollRectCellName(cell.dataIndex - 1);
            cell.gameObject.SetActive(true);
            RefreshAction?.Invoke(cell.dataIndex, cell.objIndex);
            Vector2 pos;
            if (direction == BFUIDirection.Vertical)
            {
                var d1 = downCell.AnchoredPosition.y;
                var d2 = downCell.Height + spacing;
                var d3 = cell.Height + spacing;
                if(reverse)
                {
                    pos = new Vector2(0.0f, d1 + d2);
                    cell.CachedRectTransform.anchoredPosition = pos;
                    if (ContentTrans.sizeDelta.y <= cell.AnchoredPosition.y + d3 * 0.5f)
                    {
                        ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, ContentTrans.sizeDelta.y + d3);
                    }
                }
                else
                {
                    pos = new Vector2(0.0f, d1 - d2);
                    cell.CachedRectTransform.anchoredPosition = pos;
                    if (ContentTrans.sizeDelta.y <= -cell.AnchoredPosition.y + d3 * 0.5f)
                    {
                        ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, ContentTrans.sizeDelta.y + d3);
                    }
                }

            }
            else
            {
                var d1 = downCell.AnchoredPosition.x;
                var d2 = downCell.Width + spacing;
                var d3 = cell.Width + spacing;
                if(reverse)
                {
                    pos = new Vector2(d1 - d2, 0.0f);
                    cell.CachedRectTransform.anchoredPosition = pos;
                    if (ContentTrans.sizeDelta.x <= -cell.AnchoredPosition.x + d3 * 0.5f)
                    {
                        ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, ContentTrans.sizeDelta.x + d3);
                    }
                }
                else
                {
                    pos = new Vector2(d1 + d2, 0.0f);
                    cell.CachedRectTransform.anchoredPosition = pos;
                    if (ContentTrans.sizeDelta.x <= cell.AnchoredPosition.x + d3 * 0.5f)
                    {
                        ContentTrans.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, ContentTrans.sizeDelta.x + d3);
                    }
                }
            }

            activeCells.Add(cell);

            return true;
        }

        bool TryAddUp()
        {
            var topCell = activeCells[0];
            var topIndex = topCell.dataIndex;
            if (topIndex == 1)
            {
                return false;
            }

            var cell = GetCell();
            cell.dataIndex = topIndex - 1;
            cell.name = StringConst.GetScrollRectCellName(cell.dataIndex - 1);
            cell.gameObject.SetActive(true);
            RefreshAction?.Invoke(cell.dataIndex, cell.objIndex);

            var d1 = direction == BFUIDirection.Vertical ?
            cell.Height + spacing :
            cell.Width + spacing;

            if(reverse)
            {
                var pos = direction == BFUIDirection.Vertical ?
                    new Vector2(0.0f, topCell.AnchoredPosition.y - d1) :
                    new Vector2(topCell.AnchoredPosition.x + d1, 0.0f);
                cell.CachedRectTransform.anchoredPosition = pos;
            }
            else
            {
                var pos = direction == BFUIDirection.Vertical ?
                    new Vector2(0.0f, topCell.AnchoredPosition.y + d1) :
                    new Vector2(topCell.AnchoredPosition.x - d1, 0.0f);
                cell.CachedRectTransform.anchoredPosition = pos;
            }

            activeCells.Insert(0, cell);

            return true;
        }

        BFCell GetCell()
        {
            if (cellPool.Count > 0)
            {
                return cellPool.Pop();
            }
            else
            {
                var t = Instantiate(bfCell.CachedRectTransform);
                t.SetParent(ContentTrans);
                t.localScale = Vector3.one;
                t.anchoredPosition3D = Vector3.zero;
                instantiateCount++;
                var newCell = t.GetComponent<BFCell>();
                newCell.objIndex = instantiateCount;
                OnInstantiateCell?.Invoke(newCell.gameObject);
                return newCell;
            }
        }

        void Pool(BFCell cell)
        {
            activeCells.Remove(cell);
            cell.gameObject.SetActive(false);
            cellPool.Push(cell);
        }

        bool NeedCull(BFCell cell)
        {
            if (activeCells.IndexOf(cell) == 0)
            {
                if(direction == BFUIDirection.Vertical)
                {
                    if(reverse)
                    {
                        var d1 = cell.AnchoredPosition.y + cell.Height + spacing + ContentTrans.anchoredPosition.y;
                        if (d1 < -(0.01 + topRecoveryOffset))
                        {
                            return true;
                        }
                    }
                    else
                    {
                        var d1 = cell.AnchoredPosition.y - cell.Height - spacing + ContentTrans.anchoredPosition.y;
                        if (d1 > 0.01 + topRecoveryOffset)
                        {
                            return true;
                        }
                    }
                }
                else
                {
                    if(reverse)
                    {
                        var d1 = cell.AnchoredPosition.x - cell.Width - spacing + ContentTrans.anchoredPosition.x;
                        if (d1 > 0.01 + topRecoveryOffset)
                        {
                            return true;
                        }
                    }
                    else
                    {
                        var d1 = cell.AnchoredPosition.x + cell.Width + spacing + ContentTrans.anchoredPosition.x;
                        if (d1 < -(0.01 + topRecoveryOffset))
                        {
                            return true;
                        }
                    }
                }
            }

            if(direction == BFUIDirection.Vertical)
            {
                if(reverse)
                {
                    var d2 = cell.AnchoredPosition.y + ContentTrans.anchoredPosition.y;
                    var d3 = ViewPortTrans.sizeDelta.y;
                    if (d2 > d3 + 0.01 + downRecoveryOffset)
                    {
                        return true;
                    }
                }
                else
                {
                    var d2 = cell.AnchoredPosition.y + ContentTrans.anchoredPosition.y;
                    var d3 = -ViewPortTrans.sizeDelta.y;
                    if (d2 < d3 - (0.01 + downRecoveryOffset))
                    {
                        return true;
                    }
                }
            }
            else
            {
                if(reverse)
                {
                    var d2 = cell.AnchoredPosition.x + ContentTrans.anchoredPosition.x;
                    var d3 = -ViewPortTrans.sizeDelta.x;
                    if (d2 < d3 - (0.01 + downRecoveryOffset))
                    {
                        return true;
                    }
                }
                else
                {
                    var d2 = cell.AnchoredPosition.x + ContentTrans.anchoredPosition.x;
                    var d3 = ViewPortTrans.sizeDelta.x;
                    if (d2 > d3 + 0.01 + downRecoveryOffset)
                    {
                        return true;
                    }
                }
            }

            if (cell.dataIndex > totalCount)
            {
                return true;
            }

            return false;
        }
    }
}