using System;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AddressableAssets;
using UnityEngine.ResourceManagement.AsyncOperations;
using Object = UnityEngine.Object;

namespace AibisDream.Framework
{
    public class SceneResourceLoader : MonoBehaviour
    {
        [SerializeField] private bool isPersistent;

        private readonly Dictionary<string, AsyncOperationHandle> _cache = new();
        private readonly List<AsyncOperationHandle> _uncachedHandles = new();

        private void Awake()
        {
            if (isPersistent)
                ResourceSystem.RegisterPersistentLoader(this);
            else
                ResourceSystem.RegisterSceneLoader(this);
        }

        private void OnDestroy()
        {
            ReleaseAll();

            if (isPersistent)
                ResourceSystem.UnregisterPersistentLoader(this);
            else
                ResourceSystem.UnregisterSceneLoader(this);
        }

        /// <summary>
        /// 异步加载资源（带缓存，同 Key 不重复加载）。
        /// 返回的 Handle 可在协程中 yield return。
        /// </summary>
        public AsyncOperationHandle<T> LoadAsync<T>(string key) where T : Object
        {
            if (_cache.TryGetValue(key, out var cached) && cached.IsValid())
                return cached.Convert<T>();

            var handle = Addressables.LoadAssetAsync<T>(key);
            _cache[key] = handle;
            handle.Completed += op =>
            {
                if (op.Status != AsyncOperationStatus.Succeeded)
                    Debug.LogError($"[SceneResourceLoader] Failed to load '{key}': {op.OperationException}");
            };
            return handle;
        }

        /// <summary>
        /// 异步加载资源（回调风格，带缓存）。
        /// </summary>
        public void LoadAsync<T>(string key, Action<T> onComplete, Action<string> onError = null) where T : Object
        {
            var handle = LoadAsync<T>(key);
            handle.Completed += op =>
            {
                if (op.Status == AsyncOperationStatus.Succeeded)
                    onComplete?.Invoke(op.Result);
                else
                    onError?.Invoke($"Failed to load '{key}': {op.OperationException}");
            };
        }

        /// <summary>
        /// 异步加载资源（不走缓存，每次产生独立 Handle）。
        /// 适用于 Timeline 等需要独立生命周期管理的资源。
        /// </summary>
        public AsyncOperationHandle<T> LoadUncachedAsync<T>(string key) where T : Object
        {
            var handle = Addressables.LoadAssetAsync<T>(key);
            _uncachedHandles.Add(handle);
            handle.Completed += op =>
            {
                if (op.Status != AsyncOperationStatus.Succeeded)
                    Debug.LogError($"[SceneResourceLoader] Failed to load '{key}': {op.OperationException}");
            };
            return handle;
        }

        /// <summary>
        /// 按 Label 批量预加载资源。返回的 Handle 可在协程中 yield return。
        /// </summary>
        public AsyncOperationHandle<IList<T>> PreloadByLabel<T>(string label) where T : Object
        {
            var handle = Addressables.LoadAssetsAsync<T>(label, null);
            _uncachedHandles.Add(handle);
            handle.Completed += op =>
            {
                if (op.Status != AsyncOperationStatus.Succeeded)
                    Debug.LogError($"[SceneResourceLoader] Failed to preload label '{label}': {op.OperationException}");
            };
            return handle;
        }

        /// <summary>
        /// 提前释放指定 Key 的缓存资源。
        /// </summary>
        public void EarlyRelease(string key)
        {
            if (_cache.TryGetValue(key, out var handle))
            {
                if (handle.IsValid())
                    Addressables.Release(handle);
                _cache.Remove(key);
            }
        }

        /// <summary>
        /// 提前释放指定的非缓存 Handle。
        /// </summary>
        public void EarlyRelease<T>(AsyncOperationHandle<T> handle)
        {
            if (handle.IsValid())
            {
                Addressables.Release(handle);
                _uncachedHandles.Remove(handle);
            }
        }

        /// <summary>
        /// 释放所有持有的资源 Handle。由 SceneLoader 在卸载场景前调用，或 OnDestroy 时自动调用。
        /// </summary>
        public void ReleaseAll()
        {
            foreach (var kvp in _cache)
            {
                if (kvp.Value.IsValid())
                    Addressables.Release(kvp.Value);
            }
            _cache.Clear();

            foreach (var handle in _uncachedHandles)
            {
                if (handle.IsValid())
                    Addressables.Release(handle);
            }
            _uncachedHandles.Clear();
        }

        public int CachedCount => _cache.Count;
        public int UncachedCount => _uncachedHandles.Count;
        public int TotalHandleCount => _cache.Count + _uncachedHandles.Count;
    }
}