using UnityEngine;
using UnityEngine.UI;

public class WorldHealthBar : MonoBehaviour
{
    // 最大生命值。
    [Min(1f)] public float maxHealth = 100f;

    // 当前生命值，范围会自动限制在 0 到 maxHealth 之间。
    [Min(0f)] public float currentHealth = 100f;

    // 技能能量上限，英雄默认使用100点；没有技能的小怪可关闭能量条。
    [Header("技能能量")]
    public bool showEnergyBar = true;
    [Min(1f)] public float maxEnergy = 100f;

    // 当前技能能量，范围会自动限制在 0 到 maxEnergy 之间。
    [Min(0f)]
    [SerializeField]
    private float _currentEnergy = 0f;
    
    public float currentEnergy
    {
        get => _currentEnergy;
        set
        {
            _currentEnergy = Mathf.Clamp(value, 0f, maxEnergy);
            UpdateEnergyFill();
        }
    }

    public bool IsEnergyFull => !isDead && currentEnergy >= maxEnergy;

    // 血条相对于单位头顶的额外高度。
    [Min(0f)] public float heightOffset = 0.25f;

    // 所有单位使用统一的血条世界宽度。
    [Min(0.1f)] public float barWidth = 1.2f;

    // 血条边框颜色。
    public Color borderColor = new Color(0.03f, 0.03f, 0.03f, 0.95f);

    // 死亡特效持续时间，单位为秒。
    [Min(0.1f)] public float deathEffectDuration = 1.1f;

    // 死亡时使用的浅蓝色粒子颜色。
    public Color deathEffectColor = new Color(0.55f, 0.9f, 1f, 1f);

    [Header("伤害数字")]
    public bool showDamageNumbers = true;
    [Min(0.1f)] public float damageNumberDuration = 0.8f;
    [Min(0f)] public float damageNumberRiseHeight = 1.2f;
    [Min(0f)] public float damageNumberSpawnHeight = 1.5f;
    [Min(0.01f)] public float damageNumberSize = 0.09f;
    
    // 描边宽度设为私有常量，所有角色统一使用
    private const float DamageNumberOutlineWidth = 0.025f; // 从 0.015 增加到 0.025，描边更粗

    // 血条 UI 的像素尺寸，实际显示大小由 worldWidth 控制。
    private const int PixelWidth = 100;
    private const int PixelHeight = 14;

    // 能量条紧贴血条下方，宽度更窄，高度更小。
    private const int EnergyPixelWidth = 100;  // 改为和血条一样宽
    private const int EnergyPixelHeight = 12;  // 从 8 增加到 12，更明显
    private const int BarGap = 0;  // 改为 0，让血条和能量条紧贴在一起
    private const int TotalPixelHeight = PixelHeight + BarGap + EnergyPixelHeight;

    // 世界空间 Canvas，用来承载血条 UI。
    private Canvas canvas;

    // 血条整体的 RectTransform。
    private RectTransform barRect;

    // 绿色血量填充 Image。
    private Image fillImage;

    // 金色技能能量填充 Image。
    private Image energyFillImage;

    // 血条相对于单位的本地位置。
    private Vector3 localBarPosition;

    // 血条最终使用的世界宽度。
    private float worldWidth;

    // 所有血条共用的圆角 Sprite。
    private static Sprite roundedSprite;

    // 防止死亡逻辑重复执行。
    private bool isDead;

    // 公开死亡状态供外部查询（用于胜负判定）
    public bool IsDead => isDead;

    // 初始化血量和血条 UI。
    private void Awake()
    {
        maxHealth = Mathf.Max(1f, maxHealth);
        currentHealth = Mathf.Clamp(currentHealth, 0f, maxHealth);
        maxEnergy = Mathf.Max(1f, maxEnergy);
        _currentEnergy = Mathf.Clamp(_currentEnergy, 0f, maxEnergy);
        CalculateLayout();
        CreateBar();  // 创建血条 UI 结构；无技能单位只创建血条
        UpdateFill();
        UpdateEnergyFill();
    }

    // 在 Start() 中根据最终标签设置血条颜色，确保 Instantiate 后的标签修改生效。
    private void Start()
    {
        if (fillImage != null)
        {
            fillImage.color = GetHealthFillColor();
        }
    }

    // 每帧让血条保持在单位头顶，并朝向主摄像机。
    private void LateUpdate()
    {
        if (barRect == null) return;
        barRect.localPosition = GetBarRootPosition();
        ApplyScaleCompensation();

        // 优先使用场景中名称完全为 Main Camera 的摄像机。
        Camera camera = FindMainCamera();
        if (camera == null) return;

        canvas.worldCamera = camera;
        if (camera.gameObject.name == "Main Camera")
        {
            // 使用摄像机的上方向，保证血条在摄像机画面中保持水平。
            barRect.rotation = Quaternion.LookRotation(
                camera.transform.position - barRect.position,
                camera.transform.up);
        }
        else
        {
            // 找不到 Main Camera 时，保留原来的展示逻辑。
            barRect.rotation = Quaternion.LookRotation(
                camera.transform.position - barRect.position,
                Vector3.up);
        }
    }

    // 查找场景中名称为 Main Camera 的摄像机；找不到时回退到 Camera.main。
    private Camera FindMainCamera()
    {
        GameObject mainCameraObject = GameObject.Find("Main Camera");
        if (mainCameraObject != null)
        {
            Camera namedCamera = mainCameraObject.GetComponent<Camera>();
            if (namedCamera != null && namedCamera.isActiveAndEnabled)
            {
                return namedCamera;
            }
        }

        return Camera.main;
    }

    // 直接设置当前生命值，并刷新绿色填充比例。
    public void SetHealth(float value)
    {
        if (isDead) return;

        currentHealth = Mathf.Clamp(value, 0f, maxHealth);
        UpdateFill();
        if (currentHealth <= 0f)
        {
            Die();
        }
    }

    // 让单位受到伤害，并弹出伤害数字。
    // attacker: 攻击者，用于判断受击者（自己）是敌是友，决定数字颜色和浮动方向
    public void TakeDamage(float amount, GameObject attacker = null)
    {
        bool wasDead = isDead;
        SetHealth(currentHealth - amount);
        if (showDamageNumbers && amount > 0f && !wasDead)
        {
            // 判断受击者（自己）是否是友方（Friend tag）
            bool isVictimFriend = gameObject.CompareTag("Friend");
            SpawnDamageNumber(amount, false, isVictimFriend);
        }
    }

    // 不再需要这个方法，直接用 CompareTag 判断

    // 让单位恢复生命值，并弹出绿色治疗数字。
    public void Heal(float amount)
    {
        bool wasDead = isDead;
        float healed = Mathf.Min(amount, maxHealth - currentHealth);
        SetHealth(currentHealth + amount);
        if (showDamageNumbers && healed > 0f && !wasDead)
        {
            SpawnDamageNumber(healed, true);
        }
    }

    // 增加技能能量，并返回本次增加后是否达到满能量。
    public bool AddEnergy(float amount)
    {
        if (isDead || amount <= 0f)
        {
            return false;
        }

        float previousEnergy = currentEnergy;
        currentEnergy = Mathf.Clamp(currentEnergy + amount, 0f, maxEnergy);
        UpdateEnergyFill();
        return previousEnergy < maxEnergy && currentEnergy >= maxEnergy;
    }

    // 清空技能能量并刷新能量条。
    public void ResetEnergy()
    {
        SetEnergy(0f);
    }

    // 设置下方条的当前填充值；单位用于技能能量，建筑用于生产进度。
    public void SetEnergy(float value)
    {
        if (isDead)
        {
            return;
        }

        currentEnergy = Mathf.Clamp(value, 0f, maxEnergy);
        UpdateEnergyFill();
    }

    // 处理单位死亡：隐藏模型和血条，播放蓝色向上爆散特效。
    private void Die()
    {
        isDead = true;
        currentHealth = 0f;
        UpdateFill();

        foreach (Renderer renderer in GetComponentsInChildren<Renderer>())
        {
            renderer.enabled = false;
        }

        // 立即从敌我扫描中移除，避免死亡等待期间继续被攻击。
        gameObject.SetActive(false);

        if (barRect != null)
        {
            barRect.gameObject.SetActive(false);
        }

        GameObject effect = CreateDeathEffect();
        Destroy(effect, deathEffectDuration);
        Destroy(gameObject, deathEffectDuration);
    }

    // 创建蓝色粒子爆散特效。
    private GameObject CreateDeathEffect()
    {
        GameObject effect = new GameObject("DeathEffect");
        effect.transform.position = transform.position + Vector3.up * 1.35f;

        ParticleSystem particles = effect.AddComponent<ParticleSystem>();
        particles.Stop(true, ParticleSystemStopBehavior.StopEmittingAndClear);

        var main = particles.main;
        main.playOnAwake = false;
        main.duration = deathEffectDuration;
        main.startLifetime = new ParticleSystem.MinMaxCurve(0.9f, deathEffectDuration);
        main.startSpeed = new ParticleSystem.MinMaxCurve(0.05f, 0.18f);
        main.startSize = new ParticleSystem.MinMaxCurve(0.09f, 0.2f);
        main.startRotation3D = true;
        main.startRotationX = new ParticleSystem.MinMaxCurve(0f, 6.28f);
        main.startRotationY = new ParticleSystem.MinMaxCurve(0f, 6.28f);
        main.startRotationZ = new ParticleSystem.MinMaxCurve(0f, 6.28f);
        main.startColor = deathEffectColor;
        main.maxParticles = 32;
        main.gravityModifier = new ParticleSystem.MinMaxCurve(1.6f);
        main.simulationSpace = ParticleSystemSimulationSpace.World;
        main.stopAction = ParticleSystemStopAction.None;

        var emission = particles.emission;
        emission.rateOverTime = 0f;
        emission.SetBursts(new[] { new ParticleSystem.Burst(0f, 18) });

        var shape = particles.shape;
        shape.shapeType = ParticleSystemShapeType.Sphere;
        shape.radius = 0.12f;

        // 只保留轻微水平散落，主要依靠重力向下坠落。
        var velocity = particles.velocityOverLifetime;
        velocity.enabled = true;
        velocity.space = ParticleSystemSimulationSpace.World;
        velocity.x = new ParticleSystem.MinMaxCurve(-0.08f, 0.08f);
        velocity.y = new ParticleSystem.MinMaxCurve(-0.25f, -0.05f);
        velocity.z = new ParticleSystem.MinMaxCurve(-0.08f, 0.08f);

        var collision = particles.collision;
        collision.enabled = true;
        collision.type = ParticleSystemCollisionType.World;
        collision.mode = ParticleSystemCollisionMode.Collision3D;
        collision.bounce = 0f;
        collision.lifetimeLoss = 0.15f;

        var size = particles.sizeOverLifetime;
        size.enabled = true;
        AnimationCurve fade = new AnimationCurve(
            new Keyframe(0f, 1f),
            new Keyframe(0.75f, 1f),
            new Keyframe(1f, 0f));
        size.size = new ParticleSystem.MinMaxCurve(1f, fade);

        var renderer = effect.GetComponent<ParticleSystemRenderer>();
        renderer.renderMode = ParticleSystemRenderMode.Mesh;
        renderer.mesh = CreateCrystalMesh();
        renderer.material = CreateParticleMaterial();
        particles.Play();
        return effect;
    }

    // 创建低模菱形水晶碎片 Mesh。
    private Mesh CreateCrystalMesh()
    {
        Mesh mesh = new Mesh { name = "DeathCrystal" };
        mesh.vertices = new[]
        {
            new Vector3(0f, 0.5f, 0f), new Vector3(0.5f, 0f, 0f),
            new Vector3(0f, 0f, 0.5f), new Vector3(-0.5f, 0f, 0f),
            new Vector3(0f, 0f, -0.5f), new Vector3(0f, -0.5f, 0f)
        };
        mesh.triangles = new[]
        {
            0, 1, 2, 0, 2, 3, 0, 3, 4, 0, 4, 1,
            5, 2, 1, 5, 3, 2, 5, 4, 3, 5, 1, 4
        };
        mesh.RecalculateNormals();
        mesh.RecalculateBounds();
        return mesh;
    }

    // 创建带浅蓝发光效果的水晶材质。
    private Material CreateParticleMaterial()
    {
        Shader shader = Shader.Find("Standard");
        Material material = new Material(shader);
        material.color = deathEffectColor;
        material.SetFloat("_Metallic", 0.15f);
        material.SetFloat("_Glossiness", 0.85f);
        material.SetColor("_EmissionColor", deathEffectColor * 1.6f);
        material.EnableKeyword("_EMISSION");
        return material;
    }

    // 根据单位模型或碰撞体计算血条位置和宽度。
    private void CalculateLayout()
    {
        Bounds bounds = new Bounds(transform.position, new Vector3(1f, 2f, 1f));
        bool found = false;
        foreach (Renderer renderer in GetComponentsInChildren<Renderer>(true))
        {
            if (!found)
            {
                bounds = renderer.bounds;
                found = true;
            }
            else
            {
                bounds.Encapsulate(renderer.bounds);
            }
        }

        if (!found)
        {
            CharacterController controller = GetComponent<CharacterController>();
            if (controller != null) bounds = controller.bounds;
        }

        // 血条尺寸固定，不随单位模型大小变化；只根据模型顶部调整位置。
        worldWidth = barWidth;
        // 水平方向固定对齐单位根节点，只使用模型顶部计算血条高度。
        Vector3 top = transform.InverseTransformPoint(new Vector3(transform.position.x, bounds.max.y, transform.position.z));
        float localHeightOffset = transform.lossyScale.y != 0f
            ? heightOffset / transform.lossyScale.y
            : heightOffset;
        localBarPosition = new Vector3(0f, top.y + localHeightOffset, 0f);
    }
    // 创建世界空间 Canvas、边框和绿色血量填充。
    private void CreateBar()
    {
        GameObject barObject = new GameObject("WorldHealthBar", typeof(RectTransform), typeof(Canvas), typeof(CanvasScaler));
        barObject.transform.SetParent(transform, false);
        barObject.layer = gameObject.layer;
        canvas = barObject.GetComponent<Canvas>();
        canvas.renderMode = RenderMode.WorldSpace;
        canvas.sortingOrder = 100;
        barObject.GetComponent<CanvasScaler>().dynamicPixelsPerUnit = 10f;
        barRect = barObject.GetComponent<RectTransform>();
        barRect.sizeDelta = new Vector2(PixelWidth, showEnergyBar ? TotalPixelHeight : PixelHeight);
        barRect.localScale = Vector3.one * (worldWidth / PixelWidth);
        barRect.localPosition = GetBarRootPosition();
        ApplyScaleCompensation();

        RectTransform healthRow = CreateRow(barObject.transform, "HealthBar", PixelWidth, PixelHeight, 0);
        Image background = CreateImage("Border", healthRow, RoundedSprite(), borderColor);
        SetFullRect(background.rectTransform);

        // 创建填充 Image，颜色暂时使用默认绿色，在 Start() 中根据最终标签设置
        Image inner = CreateImage("Fill", healthRow, RoundedSprite(), Color.green);
        inner.rectTransform.anchorMin = Vector2.zero;
        inner.rectTransform.anchorMax = Vector2.one;
        inner.rectTransform.offsetMin = new Vector2(2f, 2f);
        inner.rectTransform.offsetMax = new Vector2(-2f, -2f);
        inner.type = Image.Type.Filled;
        inner.fillMethod = Image.FillMethod.Horizontal;
        inner.fillOrigin = 0;
        fillImage = inner;

        if (!showEnergyBar)
        {
            energyFillImage = null;
            return;
        }

        RectTransform energyRow = CreateRow(
            barObject.transform,
            "EnergyBar",
            EnergyPixelWidth,
            EnergyPixelHeight,
            PixelHeight + BarGap);
        Image energyBackground = CreateImage("EnergyBorder", energyRow, RoundedSprite(), borderColor);
        SetFullRect(energyBackground.rectTransform);

        Image energyInner = CreateImage(
            "EnergyFill",
            energyRow,
            RoundedSprite(),
            GetEnergyFillColor());
        energyInner.rectTransform.anchorMin = Vector2.zero;
        energyInner.rectTransform.anchorMax = Vector2.one;
        energyInner.rectTransform.offsetMin = new Vector2(2f, 1f);
        energyInner.rectTransform.offsetMax = new Vector2(-2f, -1f);
        energyInner.type = Image.Type.Filled;
        energyInner.fillMethod = Image.FillMethod.Horizontal;
        energyInner.fillOrigin = 0;
        energyFillImage = energyInner;
    }

    private void ApplyScaleCompensation()
    {
        Vector3 parentScale = transform.lossyScale;
        float targetScale = worldWidth / PixelWidth;
        barRect.localScale = new Vector3(
            parentScale.x != 0f ? targetScale / parentScale.x : targetScale,
            parentScale.y != 0f ? targetScale / parentScale.y : targetScale,
            parentScale.z != 0f ? targetScale / parentScale.z : targetScale);
    }

    // 返回整体 Canvas 的位置，使血条中心保持原来的高度。
    private Vector3 GetBarRootPosition()
    {
        float pixelToWorld = worldWidth / PixelWidth;
        int barHeight = showEnergyBar ? TotalPixelHeight : PixelHeight;
        float worldEnergyOffset = (barHeight - PixelHeight) * 0.5f * pixelToWorld;
        float localEnergyOffset = transform.lossyScale.y != 0f
            ? worldEnergyOffset / transform.lossyScale.y
            : worldEnergyOffset;
        return localBarPosition - Vector3.up * localEnergyOffset;
    }

    // 创建一行固定像素高度的世界空间 UI。
    private static RectTransform CreateRow(
        Transform parent,
        string name,
        int width,
        int height,
        int topOffset)
    {
        GameObject rowObject = new GameObject(name, typeof(RectTransform));
        rowObject.transform.SetParent(parent, false);

        RectTransform rowRect = rowObject.GetComponent<RectTransform>();
        rowRect.anchorMin = new Vector2(0.5f, 1f);
        rowRect.anchorMax = new Vector2(0.5f, 1f);
        rowRect.pivot = new Vector2(0.5f, 1f);
        rowRect.sizeDelta = new Vector2(width, height);
        rowRect.anchoredPosition = new Vector2(0f, -topOffset);
        return rowRect;
    }

    private Color GetHealthFillColor()
    {
        // 使用阵营 ID 判断敌我（支持 PVP）
        var unitTeam = GetComponent<UnitTeam>();
        if (unitTeam != null && unitTeam.IsLocalPlayerTeam())
        {
            return new Color(0.1f, 0.8f, 0.18f, 1f);  // 绿色（我方）
        }
        else
        {
            return new Color(0.88f, 0.12f, 0.12f, 1f); // 红色（敌方）
        }
    }

    private Color GetEnergyFillColor()
    {
        return new Color(1f, 0.72f, 0.08f, 1f);
    }

    // 创建一个用于边框或填充的 UI Image。
    private static Image CreateImage(string name, Transform parent, Sprite sprite, Color color)
    {
        GameObject imageObject = new GameObject(name, typeof(RectTransform), typeof(Image));
        imageObject.transform.SetParent(parent, false);
        Image image = imageObject.GetComponent<Image>();
        image.sprite = sprite;
        image.color = color;
        image.raycastTarget = false;
        return image;
    }

    // 让 UI 元素铺满父级 RectTransform。
    private static void SetFullRect(RectTransform rect)
    {
        rect.anchorMin = Vector2.zero;
        rect.anchorMax = Vector2.one;
        rect.offsetMin = Vector2.zero;
        rect.offsetMax = Vector2.zero;
    }
    // 根据当前生命值更新绿色填充比例。
    private void UpdateFill()
    {
        if (fillImage != null)
        {
            fillImage.fillAmount = Mathf.Clamp01(currentHealth / maxHealth);
        }
    }

    // 根据当前技能能量更新金色填充比例。
    private void UpdateEnergyFill()
    {
        if (energyFillImage != null)
        {
            energyFillImage.fillAmount = Mathf.Clamp01(currentEnergy / maxEnergy);
        }
    }

    // 创建并缓存一个直角矩形白色 Sprite，供边框和填充复用。
    private static Sprite RoundedSprite()
    {
        if (roundedSprite != null) return roundedSprite;

        const int width = 64;
        const int height = 16;
        Texture2D texture = new Texture2D(width, height, TextureFormat.RGBA32, false);
        texture.wrapMode = TextureWrapMode.Clamp;
        texture.filterMode = FilterMode.Bilinear;
        texture.hideFlags = HideFlags.HideAndDontSave;

        // 填充纯白色，无圆角
        for (int y = 0; y < height; y++)
        {
            for (int x = 0; x < width; x++)
            {
                texture.SetPixel(x, y, Color.white);
            }
        }

        texture.Apply();
        roundedSprite = Sprite.Create(texture, new Rect(0, 0, width, height), new Vector2(0.5f, 0.5f), width);
        roundedSprite.hideFlags = HideFlags.HideAndDontSave;
        return roundedSprite;
    }

    // 在单位头顶生成一个漂浮伤害数字；数字独立于单位存活，死亡单位也能看到最后一击。
    // TextMesh 不支持原生描边，用 4 个偏移的黑色副本 + 1 个白色主字组合出黑边效果。
    private void SpawnDamageNumber(float amount, bool isHeal, bool isVictimFriend = false)
    {
        if (DamageNumber.ActiveCount >= DamageNumber.MaxActive)
        {
            return;
        }

        GameObject rootObject = new GameObject("DamageNumber");
        Vector3 spawnPosition = transform.position + Vector3.up * damageNumberSpawnHeight;
        spawnPosition.x += Random.Range(-0.3f, 0.3f);
        rootObject.transform.position = spawnPosition;

        string text = Mathf.RoundToInt(amount).ToString();
        float outline = DamageNumberOutlineWidth;

        // 8 方向黑色描边：上下左右 + 四个对角，形成更粗更均匀的描边
        CreateNumberText(rootObject.transform, text, new Vector3(-outline, 0f, 0f), Color.black, damageNumberSize, 60);      // 左
        CreateNumberText(rootObject.transform, text, new Vector3(outline, 0f, 0f), Color.black, damageNumberSize, 60);       // 右
        CreateNumberText(rootObject.transform, text, new Vector3(0f, -outline, 0f), Color.black, damageNumberSize, 60);      // 下
        CreateNumberText(rootObject.transform, text, new Vector3(0f, outline, 0f), Color.black, damageNumberSize, 60);       // 上
        CreateNumberText(rootObject.transform, text, new Vector3(-outline, -outline, 0f), Color.black, damageNumberSize, 60); // 左下
        CreateNumberText(rootObject.transform, text, new Vector3(outline, -outline, 0f), Color.black, damageNumberSize, 60);  // 右下
        CreateNumberText(rootObject.transform, text, new Vector3(-outline, outline, 0f), Color.black, damageNumberSize, 60);  // 左上
        CreateNumberText(rootObject.transform, text, new Vector3(outline, outline, 0f), Color.black, damageNumberSize, 60);   // 右上
        
        // 主字颜色：治疗=绿色，友方受伤=红色，敌方受伤=白色
        Color mainColor = isHeal ? Color.green : (isVictimFriend ? Color.red : Color.white);
        CreateNumberText(rootObject.transform, text, Vector3.zero, mainColor, damageNumberSize, 61);

        DamageNumber number = rootObject.AddComponent<DamageNumber>();
        number.duration = damageNumberDuration;
        // 友方受伤向下浮动（负值），敌方受伤向上浮动（正值）
        number.riseHeight = isVictimFriend ? -damageNumberRiseHeight : damageNumberRiseHeight;
    }

    // 创建一个配置好的数字 TextMesh 子物体。
    private static TextMesh CreateNumberText(Transform parent, string text, Vector3 localOffset, Color color, float characterSize, int sortingOrder)
    {
        GameObject textObject = new GameObject("Text");
        textObject.transform.SetParent(parent, false);
        textObject.transform.localPosition = localOffset;

        Font font = GetBuiltinFont();
        TextMesh textMesh = textObject.AddComponent<TextMesh>();
        textMesh.text = text;
        textMesh.font = font;
        textMesh.fontSize = 40;
        textMesh.characterSize = characterSize;
        textMesh.anchor = TextAnchor.MiddleCenter;
        textMesh.alignment = TextAlignment.Center;
        textMesh.fontStyle = FontStyle.Bold;
        textMesh.richText = false;
        textMesh.color = color;

        MeshRenderer textRenderer = textObject.GetComponent<MeshRenderer>();
        if (font != null)
        {
            textRenderer.sharedMaterial = font.material;
        }
        // 渲染在单位之上、血条(100)之下；白主字必须比黑边高一级，
        // 同材质同 sortingOrder 的渲染顺序不确定，后画的黑边会盖住白字。
        textRenderer.sortingOrder = sortingOrder;
        return textMesh;
    }

    // 缓存引擎内置字体；Tuanjie 2022.3 使用 LegacyRuntime，旧版本回退 Arial。
    private static Font cachedBuiltinFont;

    private static Font GetBuiltinFont()
    {
        if (cachedBuiltinFont == null)
        {
            try
            {
                cachedBuiltinFont = Resources.GetBuiltinResource<Font>("LegacyRuntime.ttf");
            }
            catch
            {
                cachedBuiltinFont = null;
            }

            if (cachedBuiltinFont == null)
            {
                try
                {
                    cachedBuiltinFont = Resources.GetBuiltinResource<Font>("Arial.ttf");
                }
                catch
                {
                    cachedBuiltinFont = null;
                }
            }
        }

        return cachedBuiltinFont;
    }
}

// 漂浮伤害数字：上升、缩放回弹、淡出后自动销毁。
// 独立于所属单位存活，即使单位死亡仍会完整播放动画。
public class DamageNumber : MonoBehaviour
{
    // 全场同时存在的伤害数字上限，防止极端情况下刷屏。
    public const int MaxActive = 60;
    public static int ActiveCount { get; private set; }

    public float duration = 0.8f;
    public float riseHeight = 1.2f;

    // 一个数字由主字 + 8 方向描边副本共 9 个 TextMesh 组成，统一驱动透明度。
    private TextMesh[] textMeshes;
    private Color[] startColors;
    private Vector3 startPosition;
    private Camera targetCamera;
    private float elapsed;

    private void Awake()
    {
        ActiveCount++;
        textMeshes = GetComponentsInChildren<TextMesh>();
        startColors = new Color[textMeshes.Length];
        for (int i = 0; i < textMeshes.Length; i++)
        {
            startColors[i] = textMeshes[i].color;
        }
        startPosition = transform.position;
    }

    private void Start()
    {
        GameObject mainCameraObject = GameObject.Find("Main Camera");
        if (mainCameraObject != null)
        {
            targetCamera = mainCameraObject.GetComponent<Camera>();
        }

        if (targetCamera == null)
        {
            targetCamera = Camera.main;
        }
    }

    private void Update()
    {
        elapsed += Time.deltaTime;
        if (elapsed >= duration)
        {
            Destroy(gameObject);
            return;
        }

        float t = elapsed / duration;

        // 匀加速上升。
        Vector3 position = startPosition;
        position.y += riseHeight * Mathf.SmoothStep(0f, 1f, t);
        transform.position = position;

        // 前20%从1.35倍缩放回弹到1倍。
        float scale = t < 0.2f ? Mathf.Lerp(1.35f, 1f, t / 0.2f) : 1f;
        transform.localScale = Vector3.one * scale;

        // 后30%淡出。
        float alpha = t < 0.7f ? 1f : 1f - (t - 0.7f) / 0.3f;
        for (int i = 0; i < textMeshes.Length; i++)
        {
            if (textMeshes[i] != null)
            {
                textMeshes[i].color = new Color(startColors[i].r, startColors[i].g, startColors[i].b, alpha);
            }
        }

        // 每帧朝向摄像机。TextMesh 可读面朝本地-Z，所以 +Z 要背向摄像机，
        // 否则文字从背面被看到会左右镜像。
        if (targetCamera != null)
        {
            transform.rotation = Quaternion.LookRotation(
                transform.position - targetCamera.transform.position,
                targetCamera.transform.up);
        }
    }

    private void OnDestroy()
    {
        ActiveCount--;
    }
}