using UnityEngine;

/// <summary>
/// 按屏幕宽高比动态拉长轨道视觉物体(track1-5)的 Y 缩放,让宽屏下轨道更饱满。
///
/// 原理：宽屏时水平视野大、轨道相对缩在中间显细。降相机高度+抬头能让轨道透视放大,
/// 但仍不够饱满。再叠加"拉长轨道 Y 缩放"填满纵向视野,视觉更满。
///
/// 关键：轨道只是背景视觉,判定是几何驱动(音符世界 Y vs 判定线世界 Y)。
/// 缩放轨道 localScale 不影响音符生成/下落/判定——它们全用世界坐标,与轨道视觉无关。
///
/// 用法：挂到场景任意物体(会自动找 track1-5 或指定 trackParent)。运行时自动扫描并缩放。
/// </summary>
[DisallowMultipleComponent]
public sealed class TrackScaler : MonoBehaviour
{
    [Tooltip("是否启用轨道缩放。关闭则恢复基准值 2.5。")]
    public bool enableScaling = true;

    [Tooltip("设计基准宽高比。16:9 = 1.7778。此比例下缩放为基准值。")]
    public float designAspect = 16f / 9f;

    [Tooltip("轨道 Y 缩放的基准值(场景序列化的初始值)。从这个值开始按宽高比放大。")]
    public float baseScaleY = 2.5f;

    [Header("宽屏(aspect > 设计)缩放")]
    [Tooltip("每偏离设计宽高比 1.0，额外叠加的 Y 缩放倍数。宽屏拉长轨道让视觉更满。")]
    public float widePerAspectScaleY = 0.8f;
    [Tooltip("Y 缩放的绝对上限。避免极端超宽屏拉得过长。")]
    public float maxScaleY = 4.5f;

    [Tooltip("(可选)轨道的父节点。留空则自动全场景查找 track1-5。")]
    public Transform trackParent;

    private Transform[] _tracks;
    private float _lastAspect = -1f;
    private bool _lastEnabled;

    private void OnEnable()
    {
        FindTracks();
        _lastAspect = -1f;
        Apply();
    }

    private void Update()
    {
        float aspect = (float)Screen.width / Mathf.Max(1, Screen.height);
        if (Mathf.Abs(aspect - _lastAspect) > 0.0001f || enableScaling != _lastEnabled)
        {
            Apply();
        }
    }

    private void FindTracks()
    {
        if (trackParent != null)
        {
            // 从指定父节点下找
            _tracks = new Transform[5];
            for (int i = 0; i < trackParent.childCount; i++)
            {
                Transform child = trackParent.GetChild(i);
                if (child.name == "track1") _tracks[0] = child;
                else if (child.name == "track2") _tracks[1] = child;
                else if (child.name == "track3") _tracks[2] = child;
                else if (child.name == "track4") _tracks[3] = child;
                else if (child.name == "track5") _tracks[4] = child;
            }
        }
        else
        {
            // 全场景查找(慢,但兜底)
            _tracks = new Transform[5];
            GameObject go1 = GameObject.Find("track1");
            GameObject go2 = GameObject.Find("track2");
            GameObject go3 = GameObject.Find("track3");
            GameObject go4 = GameObject.Find("track4");
            GameObject go5 = GameObject.Find("track5");
            if (go1 != null) _tracks[0] = go1.transform;
            if (go2 != null) _tracks[1] = go2.transform;
            if (go3 != null) _tracks[2] = go3.transform;
            if (go4 != null) _tracks[3] = go4.transform;
            if (go5 != null) _tracks[4] = go5.transform;
        }
    }

    private void Apply()
    {
        if (_tracks == null || _tracks.Length == 0)
        {
            FindTracks(); // 重试
            if (_tracks == null || _tracks.Length == 0) return;
        }

        float aspect = (float)Screen.width / Mathf.Max(1, Screen.height);
        _lastAspect = aspect;
        _lastEnabled = enableScaling;

        float targetScaleY = baseScaleY;

        if (enableScaling && aspect > designAspect)
        {
            // 宽屏：额外拉长 Y
            float dev = aspect - designAspect;
            float extra = widePerAspectScaleY * dev;
            targetScaleY = Mathf.Min(baseScaleY + extra, maxScaleY);
        }
        // aspect <= designAspect 或关闭：保持基准值

        // 应用到所有轨道
        for (int i = 0; i < _tracks.Length; i++)
        {
            if (_tracks[i] == null) continue;
            Vector3 scale = _tracks[i].localScale;
            scale.y = targetScaleY;
            _tracks[i].localScale = scale;
        }
    }
}