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

namespace BF
{
    [DisallowMultipleComponent]
    public class VerticalScrollRectOld : ScrollRectBaseOld
    {
        protected override float GetSize(RectTransform item)
        {
            float size = ContentSpacing;
            if (gridLayout != null)
            {
                size += gridLayout.cellSize.y;
            }
            else
            {
                size += LayoutUtility.GetPreferredHeight(item);
            }
            return size;
        }

        protected override float GetDimension(Vector2 vector)
        {
            return vector.y;
        }

        protected override Vector2 GetVector(float value)
        {
            return new Vector2(0, value);
        }

        protected override void Awake()
        {
            base.Awake();
            directionSign = -1;

            GridLayoutGroup layout = content.GetComponent<GridLayoutGroup>();
            if (layout != null && layout.constraint != GridLayoutGroup.Constraint.FixedColumnCount)
            {
                Debug.LogError("[VerticalScrollRect] unsupported GridLayoutGroup constraint");
            }
        }

        protected override bool UpdateItems(Bounds viewBounds, Bounds contentBounds)
        {
            bool changed = false;
            if (viewBounds.min.y < contentBounds.min.y)
            {
                float size = NewItemAtEnd(), totalSize = size;
                while (size > 0 && viewBounds.min.y < contentBounds.min.y - totalSize)
                {
                    size = NewItemAtEnd();
                    totalSize += size;
                }
                if (totalSize > 0)
                    changed = true;
            }
            else if (viewBounds.min.y > contentBounds.min.y + endThreshold)
            {
                float size = DeleteItemAtEnd(), totalSize = size;
                while (size > 0 && viewBounds.min.y > contentBounds.min.y + endThreshold + totalSize)
                {
                    size = DeleteItemAtEnd();
                    totalSize += size;
                }
                if (totalSize > 0)
                    changed = true;
            }
            if (viewBounds.max.y > contentBounds.max.y)
            {
                float size = NewItemAtStart(), totalSize = size;
                while (size > 0 && viewBounds.max.y > contentBounds.max.y + totalSize)
                {
                    size = NewItemAtStart();
                    totalSize += size;
                }
                if (totalSize > 0)
                    changed = true;
            }
            else if (viewBounds.max.y < contentBounds.max.y - startThreshold)
            {
                float size = DeleteItemAtStart(), totalSize = size;
                while (size > 0 && viewBounds.max.y < contentBounds.max.y - startThreshold - totalSize)
                {
                    size = DeleteItemAtStart();
                    totalSize += size;
                }
                if (totalSize > 0)
                    changed = true;
            }
            return changed;
        }

        public override void RefreshRealShowIndex()
        {
            base.RefreshRealShowIndex();
            Bounds viewBounds = new Bounds(viewport.rect.center, viewport.rect.size);
            for (int i = content.childCount - 1; i >= 0; i--)
            {
                var gameObject = content.GetChild(i).gameObject;
                if (!gameObject.activeSelf)
                {
                    continue;
                }
                
                Bounds bounds = GetCellBounds(i);
                if (bounds.min.y > viewBounds.max.y)
                {
                    CellObj cell = GetCell(gameObject);
                    int index = cell.index;
                    if (index < curTopIndex)
                        curTopIndex = index;
                }
                if (bounds.max.y < viewBounds.min.y)
                {
                    CellObj cell = GetCell(gameObject);
                    int cellIndex = cell.index;
                    if (cellIndex > curBottomIndex)
                        curBottomIndex = cellIndex;
                }
            }
        }

        public override bool IsNotFull()
        {
            return content.rect.height < viewport.rect.height || (cellEndIndex - cellStartIndex) % ContentConstraintCount > 0;
        }
    }
}