using Cielonos.MainGame.Characters;
using UnityEngine;

namespace Cielonos.MainGame.Effects.Feedback
{
    /// <summary>
    /// 反馈用向量转换工具。
    /// 统一处理“攻击方向”“摄像机本地方向”“反馈振幅”等常见转换，避免各个武器和角色重复实现。
    /// </summary>
    public static class FeedbackVectorUtility
    {
        private const float DirectionEpsilon = 0.0001f;

        /// <summary>
        /// 获取攻击打向目标的世界方向。
        /// 对于 Projectile，优先使用真实移动速度方向；对于 NormalArea，使用攻击者指向目标的方向。
        /// </summary>
        public static Vector3 GetAttackDirection(AttackAreaBase attackArea, CharacterBase target)
        {
            if (attackArea == null)
            {
                return Vector3.forward;
            }

            if (attackArea is Projectile)
            {
                return GetProjectileDirection(attackArea);
            }

            if (attackArea is NormalArea && attackArea.creator != null && target != null)
            {
                return NormalizeOrFallback(
                    target.CenterPoint.position - attackArea.creator.CenterPoint.position,
                    attackArea.topParent.forward);
            }

            if (attackArea.creator != null && target != null)
            {
                return NormalizeOrFallback(
                    target.CenterPoint.position - attackArea.creator.CenterPoint.position,
                    attackArea.topParent.forward);
            }

            return NormalizeOrFallback(attackArea.topParent.forward, Vector3.forward);
        }

        /// <summary>
        /// 将世界方向转换为摄像机本地方向。
        /// 摄像机不存在时返回标准化世界方向，保证调用端仍能获得稳定结果。
        /// </summary>
        public static Vector3 WorldDirectionToCameraLocal(Vector3 worldDirection, Camera camera)
        {
            Vector3 normalizedDirection = NormalizeOrFallback(worldDirection, Vector3.forward);
            return camera != null
                ? camera.transform.InverseTransformDirection(normalizedDirection).normalized
                : normalizedDirection;
        }

        /// <summary>
        /// 获取攻击方向对应的摄像机本地方向。
        /// 语义为“攻击从来源打向目标”，适合玩家受击、受击后处理、方向性摄像机反馈等场景。
        /// </summary>
        public static Vector3 GetCameraLocalAttackDirection(AttackAreaBase attackArea, CharacterBase target, Camera camera)
        {
            Vector3 attackDirection = GetAttackDirection(attackArea, target);
            return WorldDirectionToCameraLocal(attackDirection, camera);
        }

        /// <summary>
        /// 根据方向和强度生成摄像机反馈振幅。
        /// </summary>
        public static Vector3 DirectionToAmplitude(Vector3 direction, float strength)
        {
            return NormalizeOrFallback(direction, Vector3.forward) * Mathf.Max(0f, strength);
        }

        /// <summary>
        /// 根据命中点在屏幕中的横向位置生成振幅。
        /// 适合远程命中确认等“屏幕位置比物理飞行方向更重要”的反馈。
        /// </summary>
        public static Vector3 ScreenHitPositionToAmplitude(
            Vector3 hitPosition,
            Camera camera,
            float horizontalStrength,
            float verticalKick,
            float depthKick)
        {
            if (camera == null)
            {
                return new Vector3(0f, verticalKick, depthKick);
            }

            Vector3 viewportPosition = camera.WorldToViewportPoint(hitPosition);
            float screenX = viewportPosition.z >= 0f
                ? Mathf.Clamp((viewportPosition.x - 0.5f) * 2f, -1f, 1f)
                : 0f;

            return new Vector3(screenX * horizontalStrength, verticalKick, depthKick);
        }

        private static Vector3 GetProjectileDirection(AttackAreaBase attackArea)
        {
            if (attackArea.moveSm != null && attackArea.moveSm.unscaledVelocity.sqrMagnitude > DirectionEpsilon)
            {
                return attackArea.moveSm.unscaledVelocity.normalized;
            }

            return NormalizeOrFallback(attackArea.topParent.forward, Vector3.forward);
        }

        private static Vector3 NormalizeOrFallback(Vector3 direction, Vector3 fallback)
        {
            if (direction.sqrMagnitude > DirectionEpsilon)
            {
                return direction.normalized;
            }

            return fallback.sqrMagnitude > DirectionEpsilon ? fallback.normalized : Vector3.forward;
        }
    }
}