using UnityEngine;
using BrewMonster.Scripts;

namespace BrewMonster
{
    /// <summary>
    /// Utility functions for hook position/rotation calculation
    /// 挂点位置/旋转计算的工具函数
    /// </summary>
    public static class HookUtils
    {
        /// <summary>
        /// Get world position from hook Transform with offset
        /// 从挂点变换获取世界位置（带偏移）
        /// </summary>
        /// <param name="hookTransform">Hook Transform / 挂点变换</param>
        /// <param name="offset">Offset vector / 偏移向量</param>
        /// <param name="bRelative">If true, offset is relative to hook's local space; if false, absolute / 如果为true，偏移相对于挂点局部空间；如果为false，绝对偏移</param>
        /// <param name="modelTransform">Model transform for absolute offset calculation (optional) / 用于绝对偏移计算的模型变换（可选）</param>
        /// <returns>World position / 世界位置</returns>
        public static Vector3 GetHookWorldPosition(Transform hookTransform, Vector3 offset, bool bRelative, Transform modelTransform = null)
        {
            if (hookTransform == null)
                return Vector3.zero;
            
            if (bRelative)
            {
                // Relative offset: transform offset from hook's local space to world space
                // 相对偏移：将偏移从挂点的局部空间变换到世界空间
                // C++ equivalent: pHook->GetAbsoluteTM() * pOffset
                return hookTransform.TransformPoint(offset);
            }
            else
            {
                // Absolute offset: transform offset in model space, then translate to hook position
                // 绝对偏移：在模型空间中变换偏移，然后平移到挂点位置
                // C++ equivalent: 
                //   vPos = pSkin->GetAbsoluteTM() * pOffset;
                //   vPos = vPos - pSkin->GetAbsoluteTM().GetRow(3) + pHook->GetAbsoluteTM().GetRow(3);
                
                // Get model transform (skeleton root or provided)
                // 获取模型变换（骨架根或提供的）
                if (modelTransform == null)
                {
                    // Fallback: find SkeletonBuilder in hierarchy and use root bone
                    // 回退：在层次结构中查找SkeletonBuilder并使用根骨骼
                    SkeletonBuilder skeleton = hookTransform.GetComponentInParent<SkeletonBuilder>();
                    modelTransform = skeleton != null ? skeleton.rootBone : hookTransform.root;
                }
                
                // Transform offset in model's world space
                // 在模型的世界空间中变换偏移
                Vector3 offsetWorld = modelTransform.TransformPoint(offset);
                
                // Translate to hook position
                // 平移到挂点位置
                return offsetWorld - modelTransform.position + hookTransform.position;
            }
        }
        
        /// <summary>
        /// Get world rotation from hook Transform
        /// 从挂点变换获取世界旋转
        /// </summary>
        /// <param name="hookTransform">Hook Transform / 挂点变换</param>
        /// <returns>World rotation / 世界旋转</returns>
        public static Quaternion GetHookWorldRotation(Transform hookTransform)
        {
            if (hookTransform == null)
                return Quaternion.identity;
            
            return hookTransform.rotation;
        }
        
        /// <summary>
        /// Get world direction from hook Transform
        /// 从挂点变换获取世界方向
        /// </summary>
        /// <param name="hookTransform">Hook Transform / 挂点变换</param>
        /// <returns>Forward direction in world space / 世界空间的前方向</returns>
        public static Vector3 GetHookWorldForward(Transform hookTransform)
        {
            if (hookTransform == null)
                return Vector3.forward;
            
            return hookTransform.forward;
        }
    }
}