using UnityEngine;

namespace Cielonos.MainGame.Characters
{
    /// <summary>
    /// 描述单次击退/击飞的脉冲数据。
    /// 每个轴（XZ / Y）独立管理各自的脉冲，可以同时存在击退和击飞。
    /// </summary>
    public struct ImpulseData
    {
        /// <summary>归一化方向（XZ 为水平方向，Y 轴为 Vector3.up）。</summary>
        public Vector3 Direction;

        /// <summary>初始速度（m/s）。</summary>
        public float InitialSpeed;

        /// <summary>脉冲总持续时间（秒）。抛物线模式下设为 float.MaxValue，由落地检测终止。</summary>
        public float Duration;

        /// <summary>速度衰减曲线，横轴 [0,1] 归一化时间，纵轴 [0,1] 速度倍率。仅曲线模式使用。</summary>
        public AnimationCurve Curve;

        /// <summary>已经过的时间（秒）。</summary>
        public float ElapsedTime;

        /// <summary>是否使用抛物线物理公式（v = v0 - g*t）。击飞专用。</summary>
        public bool IsParabolic;

        /// <summary>抛物线模式下的重力加速度（m/s²）。</summary>
        public float Gravity;

        /// <summary>当前脉冲是否仍在生效。</summary>
        public bool IsActive => ElapsedTime < Duration && Duration > 0f;

        /// <summary>
        /// 采样当前帧的速度绝对值（m/s）。
        /// 抛物线模式返回 |v0 - g*t|，用于脉冲替换判定。
        /// </summary>
        public float SampleSpeed()
        {
            if (!IsActive) return 0f;

            if (IsParabolic)
            {
                return Mathf.Abs(InitialSpeed - Gravity * ElapsedTime);
            }

            float t = Mathf.Clamp01(ElapsedTime / Duration);
            float curveValue = Curve != null ? Curve.Evaluate(t) : (1f - t);
            return InitialSpeed * curveValue;
        }

        /// <summary>
        /// 采样当前帧的带符号速度（m/s）。仅抛物线模式有意义，正值上升、负值下落。
        /// 曲线模式始终返回正值。
        /// </summary>
        public float SampleSignedSpeed()
        {
            if (!IsActive) return 0f;

            if (IsParabolic)
            {
                return InitialSpeed - Gravity * ElapsedTime;
            }

            return SampleSpeed();
        }

        /// <summary>推进时间并返回本帧的位移向量。</summary>
        public Vector3 Advance(float deltaTime)
        {
            if (!IsActive) return Vector3.zero;

            if (IsParabolic)
            {
                // v(t) = v0 - g*t，正值上升、负值下落，产生真实抛物线
                float currentVelocity = InitialSpeed - Gravity * ElapsedTime;
                ElapsedTime += deltaTime;
                return Direction * (currentVelocity * deltaTime);
            }

            float speed = SampleSpeed();
            ElapsedTime += deltaTime;
            return Direction * (speed * deltaTime);
        }

        /// <summary>清除脉冲数据，使其失效。</summary>
        public void Clear()
        {
            ElapsedTime = float.MaxValue;
            InitialSpeed = 0f;
            Duration = 0f;
            IsParabolic = false;
            Gravity = 0f;
        }
    }

    /// <summary>
    /// 管理角色受击时的附加力（击退 / 击飞）。
    /// 使用脉冲替换机制，每个轴独立管理一个 ImpulseData。
    /// </summary>
    public class ImpulseSubmodule : SubmoduleBase<MovementSubcontrollerBase>
    {
        private const float DEFAULT_KNOCKBACK_DURATION = 0.5f;
        private const float SPEED_EPSILON = 0.01f;

        private CharacterBase character => owner.owner;

        /// <summary>水平击退脉冲（XZ 平面）。</summary>
        public ImpulseData knockbackImpulse;

        /// <summary>垂直击飞脉冲（Y 轴）。</summary>
        public ImpulseData launchImpulse;

        /// <summary>
        /// 默认的 EaseOut 衰减曲线。
        /// 起始速度最大，后半段缓慢归零，模拟"被推开后站稳"的手感。
        /// </summary>
        private static readonly AnimationCurve DefaultEaseOutCurve = new AnimationCurve(
            new Keyframe(0f, 1f, 0f, -0.5f),
            new Keyframe(1f, 0f, -2f, 0f)
        );

        public ImpulseSubmodule(MovementSubcontrollerBase movementSc) : base(movementSc)
        {
            knockbackImpulse = new ImpulseData();
            launchImpulse = new ImpulseData();
        }

        // ────────────────────────────────────────────────────────────────────
        //  Public API
        // ────────────────────────────────────────────────────────────────────

        /// <summary>
        /// 施加一次击退脉冲（XZ 平面）。
        /// 使用"取较大值替换"策略：如果新脉冲的初始速度大于当前剩余速度，则替换；否则忽略。
        /// </summary>
        /// <param name="direction">击退方向（仅使用 XZ 分量，会自动归一化）。</param>
        /// <param name="initialSpeed">初始速度（m/s）。</param>
        /// <param name="duration">持续时间（秒）。传入 0 或负数时使用默认值。</param>
        /// <param name="curve">衰减曲线。传入 null 时使用默认 EaseOut 曲线。</param>
        /// <param name="ignoreResistance">是否无视 ImpactResistance 抗性。</param>
        public void ApplyKnockback(Vector3 direction, float initialSpeed,
            float duration = DEFAULT_KNOCKBACK_DURATION, AnimationCurve curve = null,
            bool ignoreResistance = false)
        {
            float rawDuration = duration > 0f ? duration : DEFAULT_KNOCKBACK_DURATION;
            ResistanceResult result = ApplyResistance(initialSpeed, rawDuration, ignoreResistance);
            if (result.Speed <= SPEED_EPSILON) return;

            Vector3 flatDir = new Vector3(direction.x, 0f, direction.z).normalized;
            if (flatDir.sqrMagnitude < 0.001f) return;

            AnimationCurve effectiveCurve = curve ?? DefaultEaseOutCurve;

            // 取较大值替换：新脉冲速度 > 当前剩余速度时才替换
            float remainingSpeed = knockbackImpulse.SampleSpeed();
            if (result.Speed > remainingSpeed)
            {
                knockbackImpulse = new ImpulseData
                {
                    Direction = flatDir,
                    InitialSpeed = result.Speed,
                    Duration = result.Duration,
                    Curve = effectiveCurve,
                    ElapsedTime = 0f
                };
            }
        }

        /// <summary>
        /// 施加一次击飞脉冲（Y 轴）。
        /// 当 isParabolic 为 true 时使用物理公式 v = v0 - g*t 产生真实抛物线轨迹，
        /// 脉冲由落地检测终止而非固定时长；为 false 时使用曲线衰减。
        /// </summary>
        /// <param name="initialSpeed">初始上升速度（m/s）。</param>
        /// <param name="duration">持续时间（秒）。抛物线模式下忽略此参数。</param>
        /// <param name="curve">衰减曲线。抛物线模式下忽略此参数。</param>
        /// <param name="ignoreResistance">是否无视 ImpactResistance 抗性。</param>
        /// <param name="isParabolic">是否使用抛物线物理。默认 false。</param>
        public void ApplyLaunch(float initialSpeed, float duration,
            AnimationCurve curve = null, bool ignoreResistance = true,
            bool isParabolic = false)
        {
            float rawDuration = duration > 0f ? duration : DEFAULT_KNOCKBACK_DURATION;
            ResistanceResult result = ApplyResistance(initialSpeed, rawDuration, ignoreResistance);
            if (result.Speed <= SPEED_EPSILON) return;

            float remainingSpeed = launchImpulse.SampleSpeed();
            if (result.Speed <= remainingSpeed) return;

            if (isParabolic)
            {
                // 清除跳跃速度，避免 jumpVelocity 与击飞脉冲叠加
                owner.jumpVelocity = 0f;
            }

            launchImpulse = new ImpulseData
            {
                Direction = Vector3.up,
                InitialSpeed = result.Speed,
                // 抛物线模式：重力接管衰减，Duration 设为极大值，由落地检测终止
                Duration = isParabolic ? float.MaxValue : result.Duration,
                Curve = isParabolic ? null : (curve ?? DefaultEaseOutCurve),
                ElapsedTime = 0f,
                IsParabolic = isParabolic,
                Gravity = isParabolic ? owner.normalGravity : 0f
            };
        }

        /// <summary>
        /// 施加一次完整的力（自动拆分为 XZ 击退 + Y 击飞）。
        /// 兼容旧的 force 矢量调用方式。
        /// </summary>
        /// <param name="force">力的矢量（XZ 分量为击退，Y 分量为击飞）。</param>
        /// <param name="ignoreResistance">是否无视 ImpactResistance 抗性。</param>
        /// <param name="duration">持续时间（秒）。</param>
        /// <param name="curve">衰减曲线。</param>
        /// <param name="isParabolic">Y 分量是否使用抛物线物理。</param>
        public void ApplyImpulse(Vector3 force, bool ignoreResistance = false,
            float duration = DEFAULT_KNOCKBACK_DURATION, AnimationCurve curve = null,
            bool isParabolic = false)
        {
            Vector3 flatForce = new Vector3(force.x, 0f, force.z);
            float xzSpeed = flatForce.magnitude;

            if (xzSpeed > SPEED_EPSILON)
            {
                ApplyKnockback(flatForce, xzSpeed, duration, curve, ignoreResistance);
            }

            if (Mathf.Abs(force.y) > SPEED_EPSILON)
            {
                ApplyLaunch(force.y, duration, curve, ignoreResistance, isParabolic);
            }
        }

        /// <summary>
        /// 每帧调用，推进脉冲时间并返回本帧的总位移量。
        /// </summary>
        public Vector3 Update(float deltaTime)
        {
            Vector3 displacement = Vector3.zero;

            if (knockbackImpulse.IsActive)
            {
                displacement += knockbackImpulse.Advance(deltaTime);
            }

            if (launchImpulse.IsActive)
            {
                displacement += launchImpulse.Advance(deltaTime);
            }

            return displacement;
        }

        /// <summary>
        /// 立即清除所有正在生效的脉冲。
        /// </summary>
        public void ClearAll()
        {
            knockbackImpulse.Clear();
            launchImpulse.Clear();
        }

        /// <summary>
        /// 立即清除 Y 轴击飞脉冲。
        /// </summary>
        public void ClearLaunch()
        {
            launchImpulse.Clear();
        }

        /// <summary>当前是否有任何脉冲在生效。</summary>
        public bool HasActiveImpulse => knockbackImpulse.IsActive || launchImpulse.IsActive;

        /// <summary>当前 XZ 击退的剩余速度。</summary>
        public float CurrentKnockbackSpeed => knockbackImpulse.SampleSpeed();

        /// <summary>当前 Y 击飞的剩余速度（绝对值）。</summary>
        public float CurrentLaunchSpeed => launchImpulse.SampleSpeed();

        // ────────────────────────────────────────────────────────────────────
        //  Internal
        // ────────────────────────────────────────────────────────────────────

        /// <summary>
        /// 抗性缩放结果：同时包含速度和持续时间的缩放值。
        /// </summary>
        private readonly struct ResistanceResult
        {
            public readonly float Speed;
            public readonly float Duration;

            public ResistanceResult(float speed, float duration)
            {
                Speed = speed;
                Duration = duration;
            }
        }

        /// <summary>
        /// 根据角色 ImpulseResistance 属性缩放脉冲参数。
        /// 速度线性缩放；持续时间使用平方根缩放，使高抗性敌人更快停下而非慢慢滑行。
        /// </summary>
        /// <param name="speed">原始速度。</param>
        /// <param name="duration">原始持续时间。</param>
        /// <param name="ignoreResistance">是否无视抗性（击飞等）。</param>
        private ResistanceResult ApplyResistance(float speed, float duration, bool ignoreResistance)
        {
            if (ignoreResistance) return new ResistanceResult(speed, duration);

            float resistance = character.attributeSm["ImpulseResistance"];
            float multiplier = Mathf.Clamp01(1f - (resistance / 100f));

            float scaledSpeed = speed * multiplier;
            // 持续时间使用 sqrt 缩放：resistance 75 → speed 25%, duration 50%
            // 重型敌人会快速站稳，而非以低速缓缓滑行
            float scaledDuration = duration * Mathf.Sqrt(multiplier);

            return new ResistanceResult(scaledSpeed, scaledDuration);
        }
    }
}