using System.IO;
using UnityEngine;

namespace LibMMD.Unity3D.Animation
{
    // Caches the single most-recently-baked kinematic-FK pose (see MmdAnimationClipBaker) keyed
    // by (model path+mtime, motion path+mtime). MmdAnimator reads through this instead of
    // re-baking whenever a model+VMD reload turns out to be the exact same combination as last
    // time - eg. toggling PhysicsMode and clicking Load again in MmdSettingsController, which
    // always tears down and rebuilds the whole MmdGameObject since physics components can't be
    // swapped live.
    //
    // Only a single entry is kept: this exists for the reload-and-tweak-settings workflow, not
    // for juggling many simultaneously-active motions. Storing a new entry replaces the previous
    // one - BakedPose is plain data (no UnityEngine.Object), so there's no Destroy()/ownership
    // bookkeeping needed, unlike the AnimationClip this used to cache.
    internal static class MmdBakedClipCache
    {
        private static string _key;
        private static MmdAnimationClipBaker.BakedPose _pose;

        [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
        private static void ResetForPlaySession()
        {
            _key = null;
            _pose = null;
        }

        public static string BuildKey(string modelPath, string motionPath)
        {
            if (string.IsNullOrEmpty(modelPath) || string.IsNullOrEmpty(motionPath))
            {
                return null;
            }
            try
            {
                var model = new FileInfo(modelPath);
                var motion = new FileInfo(motionPath);
                if (!model.Exists || !motion.Exists) return null;
                return $"{model.FullName}|{model.Length}|{model.LastWriteTimeUtc.Ticks}|" +
                       $"{motion.FullName}|{motion.Length}|{motion.LastWriteTimeUtc.Ticks}";
            }
            catch (System.Exception)
            {
                return null;
            }
        }

        public static MmdAnimationClipBaker.BakedPose TryGet(string key)
        {
            return key != null && key == _key ? _pose : null;
        }

        public static void Store(string key, MmdAnimationClipBaker.BakedPose pose)
        {
            if (key == null)
            {
                return;
            }
            _key = key;
            _pose = pose;
        }
    }
}