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

public class RankUpLooper : MonoBehaviour
{
    public ScrollRect scrollRect;
    public RectTransform content;
    public RectTransform viewport;

    public GameObject itemPrefab;
    public int itemCount = 20;

    public int targetRankIndex = 2;
    public float scrollSpeed = 2000f;
    public float scrollDuration = 1.5f;
    public float stopDelay = 0.5f;

    private RectTransform highlightItem;
    private float itemHeight;
    private bool isAnimating = false;
    private float contentResetThreshold;

    private List<GameObject> allItems = new List<GameObject>();
    public void OnClickRankUp()
    {
        PlayRankUp(currentRankIndex: 10, targetRankIndex: 2);// 从第10名冲到第2名（模拟）
    }
    void Start()
    {
        InitRankList();
    }

    void InitRankList()
    {
        allItems.Clear();
        foreach (Transform child in content) Destroy(child.gameObject);

        // 创建原始项
        for (int i = 0; i < itemCount; i++)
        {
            var item = Instantiate(itemPrefab, content);
            item.GetComponentInChildren<Text>().text = $"#{i + 1}";
            allItems.Add(item);
        }

        // 复制一轮，实现循环
        for (int i = 0; i < itemCount; i++)
        {
            var clone = Instantiate(itemPrefab, content);
            clone.GetComponentInChildren<Text>().text = $"#{i + 1} (copy)";
            allItems.Add(clone);
        }

        LayoutRebuilder.ForceRebuildLayoutImmediate(content);

        // 获取 item 高度
        itemHeight = allItems[0].GetComponent<RectTransform>().rect.height;

        contentResetThreshold = itemHeight * itemCount;
    }

    public void PlayRankUp(int currentRankIndex, int targetRankIndex)
    {
        if (isAnimating) return;

        this.targetRankIndex = targetRankIndex;

        var original = allItems[currentRankIndex - 1];
        highlightItem = Instantiate(original, viewport).GetComponent<RectTransform>();
        highlightItem.name = "HighlightItem";
        highlightItem.SetAsLastSibling();

        if (!highlightItem.TryGetComponent(out CanvasGroup group))
            group = highlightItem.gameObject.AddComponent<CanvasGroup>();
        group.alpha = 1f;

        highlightItem.localScale = Vector3.one * 1.2f;

        isAnimating = true;
        scrollRect.enabled = false;

        // 🔄 强制刷新布局
        LayoutRebuilder.ForceRebuildLayoutImmediate(content);

        itemHeight = allItems[0].GetComponent<RectTransform>().rect.height;
        contentResetThreshold = itemHeight * itemCount;

        // 🎯 提前计算目标位置
        Vector3 targetPosition = CalculateTargetLocalPosition(targetRankIndex);

        // 启动滚动协程（传入目标位置）
        StartCoroutine(ScrollAndStop(targetPosition));
    }


    // IEnumerator DelayedScroll()
    // {
    //     // 🔄 强制更新布局
    //     LayoutRebuilder.ForceRebuildLayoutImmediate(content);

    //     // ⏳ 等待一帧，确保布局完成
    //     yield return new WaitForEndOfFrame();

    //     // 再次确认布局高度等
    //     itemHeight = allItems[0].GetComponent<RectTransform>().rect.height;
    //     contentResetThreshold = itemHeight * itemCount;

    //     // 🔥 启动滚动
    //     StartCoroutine(ScrollAndStop());
    // }


    IEnumerator ScrollAndStop(Vector3 targetPos)
    {
        float elapsed = 0f;

        while (elapsed < scrollDuration)
        {
            content.anchoredPosition += Vector2.up * scrollSpeed * Time.deltaTime;

            // 无限滚动逻辑
            if (content.anchoredPosition.y >= contentResetThreshold)
            {
                content.anchoredPosition -= Vector2.up * contentResetThreshold;
            }

            elapsed += Time.deltaTime;
            yield return null;
        }

        yield return new WaitForSeconds(stopDelay);

        SnapToTarget(targetPos);
    }


    void SnapToTarget(Vector3 targetPos)
    {
        content.DOAnchorPos(targetPos, 0.6f).SetEase(Ease.OutCubic);

        highlightItem.DOScale(Vector3.one, 0.3f).SetEase(Ease.OutBack);
        highlightItem.DOAnchorPosY(0, 0.4f).SetEase(Ease.OutSine).OnComplete(() =>
        {
            isAnimating = false;
        });
    }
    private Vector3 CalculateTargetLocalPosition(int targetRank)
    {
        float spacing = 0f;
        float totalItemHeight = itemHeight + spacing;
        float contentY = (targetRank - 1) * totalItemHeight;
        float centeredOffset = contentY - (viewport.rect.height - totalItemHeight) / 2f;

        // 限制 offset 范围
        centeredOffset = Mathf.Clamp(centeredOffset, 0, content.rect.height - viewport.rect.height);

        return new Vector3(0f, centeredOffset, 0f);
    }
    void UpdateHighlightPosition()
    {
        RectTransform targetItem = allItems[targetRankIndex - 1].GetComponent<RectTransform>();
        Vector3 worldPos = targetItem.position;
        Vector2 localPoint;
        RectTransformUtility.ScreenPointToLocalPointInRectangle(viewport, worldPos, null, out localPoint);
        highlightItem.anchoredPosition = localPoint;
    }


    // void SnapToTarget()
    // {
    //     // 停止后直接对 content 归位
    //     float targetY = itemHeight * (targetRankIndex - 1);
    //     float totalContentHeight = content.rect.height;
    //     float viewHeight = viewport.rect.height;
    //     float offset = Mathf.Clamp(targetY - (viewHeight - itemHeight) / 2f, 0, totalContentHeight - viewHeight);
    //     content.anchoredPosition = new Vector2(0, offset);

    //     // 获取目标 item 的本地位置（在 content 中的位置）
    //     RectTransform targetItem = allItems[targetRankIndex - 1].GetComponent<RectTransform>();

    //     // 计算目标位置相对 viewport 的 localPosition
    //     Vector3 worldPos = targetItem.position;
    //     Vector2 localPoint;
    //     RectTransformUtility.ScreenPointToLocalPointInRectangle(viewport, worldPos, null, out localPoint);

    //     // Animate highlightItem 到目标位置
    //     highlightItem.DOAnchorPos(localPoint, 0.4f).SetEase(Ease.OutSine);
    //     highlightItem.DOScale(Vector3.one, 0.3f).SetEase(Ease.OutBack).OnComplete(() =>
    //     {
    //         isAnimating = false;
    //     });
    // }

}