using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using YooAsset;

namespace HotUpdate.UI
{
    /// <summary>
    /// 异步加载并持有资源句柄，随 UiManager 销毁统一释放。
    /// </summary>
    public sealed class UiPrefabLoader : IDisposable
    {
        public const string PrefabFolder = "Assets/Bundles/UI/Prefab";
        readonly ResourcePackage _preferredPackage;
        readonly string _folder;
        readonly Dictionary<string, GameObject> _cache = new Dictionary<string, GameObject>();
        readonly List<AssetHandle> _handles = new List<AssetHandle>();
        bool _disposed;

        public UiPrefabLoader(ResourcePackage preferredPackage = null, string folder = PrefabFolder)
        {
            _preferredPackage = preferredPackage;
            _folder = folder;
        }

        public IEnumerator LoadAsync(string prefabName, Action<GameObject> onLoaded)
        {
            if (_disposed || string.IsNullOrEmpty(prefabName))
            {
                onLoaded?.Invoke(null);
                yield break;
            }
            if (_cache.TryGetValue(prefabName, out var cached) && cached != null)
            {
                onLoaded?.Invoke(cached);
                yield break;
            }
            var packages = new List<ResourcePackage>();
            if (_preferredPackage != null) packages.Add(_preferredPackage);
            if (YooAssets.IsInitialized)
            {
                foreach (var name in new[] { "DefaultPackage", "Art" })
                    if (YooAssets.TryGetPackage(name, out var pkg) && !packages.Contains(pkg))
                        packages.Add(pkg);
            }
            foreach (var package in packages)
            {
                if (package.InitializeStatus != EOperationStatus.Succeeded) continue;
                foreach (var address in new[] { prefabName, $"{_folder}/{prefabName}.prefab" })
                {
                    if (!package.IsLocationValid(address)) continue;
                    var handle = package.LoadAssetAsync<GameObject>(address);
                    _handles.Add(handle);
                    yield return handle;
                    if (_disposed) yield break;
                    if (handle.Status == EOperationStatus.Succeeded)
                    {
                        var prefab = handle.GetAssetObject<GameObject>();
                        if (prefab != null)
                        {
                            _cache[prefabName] = prefab;
                            onLoaded?.Invoke(prefab);
                            yield break;
                        }
                    }
                    _handles.Remove(handle);
                    handle.Release();
                }
            }

#if UNITY_EDITOR
            var editorPrefab = UnityEditor.AssetDatabase.LoadAssetAtPath<GameObject>($"{_folder}/{prefabName}.prefab");
            if (editorPrefab != null) _cache[prefabName] = editorPrefab;
            onLoaded?.Invoke(editorPrefab);
#else
            onLoaded?.Invoke(null);
#endif
        }

        public void Dispose()
        {
            if (_disposed) return;
            _disposed = true;
            foreach (var handle in _handles) handle.Release();
            _handles.Clear();
            _cache.Clear();
        }
    }
}