using System;
using System.Collections;
using AOT.Boot;
using AOT.UI;
using UnityEngine;
using YooAsset;

namespace AOT.Patch
{
    /// <summary>
    /// 启动补丁：version 门控 → YooAsset 初始化/更新 → 回调。
    /// </summary>
    public sealed class PatchRunner
    {
        readonly MonoBehaviour _host;
        readonly BootSettings _settings;
        readonly BootPatchView _view;

        public PatchRunner(MonoBehaviour host, BootSettings settings, BootPatchView view)
        {
            _host = host;
            _settings = settings;
            _view = view;
        }

        public IEnumerator Run(Action<BootContext, string> onDone)
        {
            _view?.SetStatus("检查版本…");
            _view?.SetProgress(0.05f);

            VersionInfo version = null;
            string versionError = null;
            yield return new VersionClient(_settings.VersionUrl, _settings.AllowStreamingVersionFallback)
                .Fetch((info, err) =>
                {
                    version = info;
                    versionError = err;
                });

            if (version == null)
            {
                // 无 CDN 时仍允许编辑器直通；真机 Host/Web 则失败。
                if (!CanContinueWithoutVersion())
                {
                    onDone?.Invoke(null, $"获取 version.json 失败: {versionError}");
                    yield break;
                }

                version = new VersionInfo
                {
                    appVersionMin = _settings.AppVersion,
                    appVersionMax = _settings.AppVersion,
                    resVersion = "local",
                    cdnRoot = _settings.DefaultCdnRoot,
                    packages = new[] { _settings.PackageName },
                };
                _view?.SetStatus($"版本回退本地 ({versionError})");
            }
            else
            {
                _view?.SetStatus($"远程版本 {version.resVersion}");
            }

            if (VersionInfo.CompareVersion(_settings.AppVersion, version.appVersionMin) < 0)
            {
                onDone?.Invoke(null, $"壳版本过低，请更新微信小游戏包（当前 {_settings.AppVersion} < 最低 {version.appVersionMin}）");
                yield break;
            }

            string cdnRoot = string.IsNullOrEmpty(version.cdnRoot) ? _settings.DefaultCdnRoot : version.cdnRoot;
            var ctx = new BootContext
            {
                AppVersion = _settings.AppVersion,
                ResVersion = version.resVersion,
                CdnRoot = cdnRoot,
                PackageName = _settings.PackageName,
                WsUrlTemplate = _settings.WsUrlTemplate,
            };

#if UNITY_EDITOR
            if (_settings.EditorDirectHotUpdate)
            {
                _view?.SetStatus("编辑器直通热更（跳过资源补丁）");
                _view?.SetProgress(0.9f);
                onDone?.Invoke(ctx, null);
                yield break;
            }
#endif

            _view?.SetStatus("初始化资源系统…");
            _view?.SetProgress(0.15f);

            if (!YooAssets.IsInitialized)
                YooAssets.Initialize();

            if (!YooAssets.TryGetPackage(_settings.PackageName, out var package))
                package = YooAssets.CreatePackage(_settings.PackageName);
            ctx.Package = package;

            var playMode = ResolvePlayMode();
            var initOp = CreateInitializeOperation(package, playMode, cdnRoot);
            if (initOp == null)
            {
                onDone?.Invoke(null, $"不支持的 PlayMode: {playMode}");
                yield break;
            }

            yield return initOp;
            if (initOp.Status != EOperationStatus.Succeeded)
            {
                onDone?.Invoke(null, $"YooAsset 初始化失败: {initOp.Error}");
                yield break;
            }

            _view?.SetStatus("请求资源版本…");
            _view?.SetProgress(0.35f);
            var versionOp = package.RequestPackageVersionAsync();
            yield return versionOp;
            if (versionOp.Status != EOperationStatus.Succeeded)
            {
                onDone?.Invoke(null, $"请求 PackageVersion 失败: {versionOp.Error}");
                yield break;
            }

            _view?.SetStatus($"更新清单 {versionOp.PackageVersion}");
            _view?.SetProgress(0.5f);
            var manifestOp = package.LoadPackageManifestAsync(new LoadPackageManifestOptions(versionOp.PackageVersion, 60));
            yield return manifestOp;
            if (manifestOp.Status != EOperationStatus.Succeeded)
            {
                onDone?.Invoke(null, $"更新清单失败: {manifestOp.Error}");
                yield break;
            }

            _view?.SetStatus("下载资源…");
            var downloader = package.CreateResourceDownloader(new ResourceDownloaderOptions(10, 3));
            if (downloader.TotalDownloadCount > 0)
            {
                downloader.DownloadProgressChanged += info =>
                {
                    _view?.SetProgress(0.5f + info.Progress * 0.4f);
                    _view?.SetStatus($"下载 {info.CurrentDownloadCount}/{info.TotalDownloadCount}");
                };
                downloader.StartDownload();
                yield return downloader;
                if (downloader.Status != EOperationStatus.Succeeded)
                {
                    onDone?.Invoke(null, $"下载失败: {downloader.Error}");
                    yield break;
                }
            }

            _view?.SetProgress(0.95f);
            _view?.SetStatus("资源就绪");
            onDone?.Invoke(ctx, null);
        }

        bool CanContinueWithoutVersion()
        {
#if UNITY_EDITOR
            return _settings.EditorDirectHotUpdate;
#else
            return false;
#endif
        }

        EPlayMode ResolvePlayMode()
        {
#if UNITY_EDITOR
            return _settings.PlayMode;
#elif UNITY_WEBGL
            return EPlayMode.WebPlayMode;
#else
            return _settings.PlayMode == EPlayMode.EditorSimulateMode
                ? EPlayMode.HostPlayMode
                : _settings.PlayMode;
#endif
        }

        InitializePackageOperation CreateInitializeOperation(ResourcePackage package, EPlayMode playMode, string cdnRoot)
        {
            if (playMode == EPlayMode.EditorSimulateMode)
            {
#if UNITY_EDITOR
                var buildResult = EditorSimulateBuildInvoker.Build(_settings.PackageName, (int)EBundleType.VirtualAssetBundle);
                var options = new EditorSimulateModeOptions
                {
                    EditorFileSystemParameters = FileSystemParameters.CreateDefaultEditorFileSystemParameters(buildResult.PackageRootDirectory)
                };
                return package.InitializePackageAsync(options);
#else
                return null;
#endif
            }

            if (playMode == EPlayMode.OfflinePlayMode)
            {
                var options = new OfflinePlayModeOptions
                {
                    BuiltinFileSystemParameters = FileSystemParameters.CreateDefaultBuiltinFileSystemParameters()
                };
                return package.InitializePackageAsync(options);
            }

            if (playMode == EPlayMode.HostPlayMode)
            {
                var remote = new CdnRemoteService(cdnRoot);
                var options = new HostPlayModeOptions
                {
                    BuiltinFileSystemParameters = FileSystemParameters.CreateDefaultBuiltinFileSystemParameters(),
                    CacheFileSystemParameters = FileSystemParameters.CreateDefaultSandboxFileSystemParameters(remote)
                };
                options.BuiltinFileSystemParameters.AddParameter(EFileSystemParameter.CopyBuiltinPackageManifest, true);
                return package.InitializePackageAsync(options);
            }

            if (playMode == EPlayMode.WebPlayMode)
            {
                // 微信小游戏正式接入时替换为 WechatFileSystem；M0 先用默认 WebNetwork。
                var remote = new CdnRemoteService(cdnRoot);
                var options = new WebPlayModeOptions
                {
                    WebNetworkFileSystemParameters = FileSystemParameters.CreateDefaultWebNetworkFileSystemParameters(remote, true)
                };
                return package.InitializePackageAsync(options);
            }

            return null;
        }
    }
}