using System;
using System.Collections;
using System.Collections.Generic;
using System.Threading.Tasks;
using AibisDream.Framework;
using AibisDream.UI;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 存读档流程编排层：连接 UI、<see cref="SnapshotService"/> 与槽位系统。
    /// </summary>
    public static class SaveRestoreOrchestrator
    {
        /// <summary>是否正在读档还原中；供 UI / 日志 / 外部系统观察。</summary>
        public static bool IsRestoring { get; private set; }

        /// <summary>是否处于自动存档抑制作用域；真正用于防止读档期间覆盖 slot_0。</summary>
        public static bool IsAutoSaveSuppressed => _autoSaveSuppressDepth > 0;

        /// <summary>是否正在异步捕获或写入自动档；供只读诊断 UI 使用。</summary>
        public static bool IsSaving => _isAutoSaving;

        public static IReadOnlyList<string> LastRestoreLog => _lastRestoreLog;

        private static bool _isAutoSaving;
        private static int _autoSaveSuppressDepth;
        private static readonly List<string> _lastRestoreLog = new();

        /// <summary>启动自动存档协程（手动/调试入口）。</summary>
        public static void TryAutoSave()
        {
            if (YarnVariableStorage.Instance == null)
            {
                Debug.LogError("[SaveRestoreOrchestrator] YarnVariableStorage 未初始化");
                return;
            }

            if (!SavePointEvaluator.CanAutoSave(out var reason))
            {
                Debug.LogWarning($"[SaveRestoreOrchestrator] 当前不是可存点，跳过自动存档：{reason}");
                return;
            }

            var (triggerNodeName, _) = DialogController.Instance.GetCurrentNodeContext();
            DialogController.Instance.StartCoroutine(AutoSaveRoutine(triggerNodeName));
        }

        /// <summary>自动存档协程：settle 一帧 → 主线程 Capture → 后台序列化写盘（不阻塞主线程）。</summary>
        /// <param name="triggerNodeName">见 <see cref="SnapshotCapture.Capture"/>；显式 save 传 null。</param>
        /// <param name="omitAnchor">为 true 时不写入 Yarn 节点 anchor。</param>
        public static IEnumerator AutoSaveRoutine(string triggerNodeName = null, bool omitAnchor = false)
        {
            if (_isAutoSaving)
            {
                Debug.LogWarning("[SaveRestoreOrchestrator] 存档进行中，跳过重复请求。");
                yield break;
            }

            yield return null;

            if (_isAutoSaving)
            {
                Debug.LogWarning("[SaveRestoreOrchestrator] 存档进行中，跳过重复请求。");
                yield break;
            }

            _isAutoSaving = true;
            var infoPanel = UIManager.Instance.GetPanel<InfoPanel>();
            infoPanel?.ShowSaveLoading();

            SaveSnapshot snapshot;
            byte[] thumbnail;

            try
            {
                using (new CodeTimer("SaveSnapshot"))
                {
                    snapshot = SnapshotService.Capture(triggerNodeName, omitAnchor);
                    thumbnail = SlotThumbnailCapture.CapturePng();
                }
            }
            catch (Exception ex)
            {
                Debug.LogError($"[SaveRestoreOrchestrator] 自动存档 Capture 失败: {ex}");
                infoPanel?.HideSaveLoading();
                _isAutoSaving = false;
                yield break;
            }

            infoPanel?.HideSaveLoading();

            _ = SlotManager.SaveToAutoSlotAsync(snapshot, thumbnail).ContinueWith(
                writeTask =>
                {
                    if (writeTask.IsFaulted)
                    {
                        Debug.LogError(
                            $"[SaveRestoreOrchestrator] 自动存档写盘失败: {writeTask.Exception?.GetBaseException()}");
                    }

                    _isAutoSaving = false;
                },
                TaskContinuationOptions.ExecuteSynchronously);

            if (omitAnchor || (snapshot?.anchor != null && string.IsNullOrEmpty(snapshot.anchor.nodeName)))
            {
                Debug.Log("[SaveRestoreOrchestrator] 已保存无 Yarn 节点 anchor 的状态。");
            }
        }

        /// <summary>
        /// Yarn <c>&lt;&lt;save&gt;&gt;</c> 显式存档：默认 omit anchor，调用方需已通过 <see cref="SavePointEvaluator.CanExplicitSave"/>。
        /// </summary>
        public static IEnumerator ExplicitSaveRoutine()
        {
            yield return AutoSaveRoutine(triggerNodeName: null, omitAnchor: true);
        }

        /// <summary>将当前自动档复制到指定手动档。</summary>
        public static void CreateManualSlot(int slotIndex)
        {
            if (!SavePointEvaluator.CanManualSave(out var reason))
            {
                Debug.LogWarning($"[SaveRestoreOrchestrator] 当前不可手动存档：{reason}");
                return;
            }

            SlotManager.CopyAutoToManual(slotIndex);
        }

        internal static RestorePreparation PrepareRestoreFromSlot(
            int slotIndex,
            TalkSceneGraphIndex talkSceneIndex,
            RestoreOptions options)
        {
            var sourceLabel = $"slot_{slotIndex}";
            SaveSnapshot snapshot;
            try
            {
                snapshot = SlotManager.LoadSnapshot(slotIndex);
            }
            catch (Exception ex)
            {
                return FailedPreparation(sourceLabel, "LoadSnapshot", ex.Message, options);
            }

            if (snapshot == null)
            {
                return FailedPreparation(
                    sourceLabel,
                    "LoadSnapshot",
                    $"Slot {slotIndex} does not exist or could not be read.",
                    options);
            }

            return PrepareSnapshot(snapshot, sourceLabel, talkSceneIndex, options);
        }

        internal static IEnumerator ExecutePreparedRestore(
            RestorePreparation preparation,
            Func<bool> isCancellationRequested)
        {
            if (preparation?.Success != true)
            {
                yield break;
            }

            var result = preparation.Result;
            result.Success = false;

            using (SuppressAutoSaveScope($"RestoreSnapshot:{preparation.SourceLabel}"))
            {
                IsRestoring = true;
                ResetRestoreLog(preparation.SourceLabel);
                var context = new SnapshotRestoreContext(
                    preparation.Snapshot,
                    preparation.TargetTalkScene,
                    strictMode: preparation.Options?.StrictValidation ?? true,
                    logStep: AddRestoreLog);

                try
                {
                    SnapshotRegistry.EnsureInitialized();
                    yield return SnapshotRestore.RestoreState(
                        YarnVariableStorage.Instance,
                        preparation.Snapshot,
                        context,
                        isCancellationRequested);

                    if (ShouldCancel(isCancellationRequested, result, context))
                    {
                        yield break;
                    }

                    if (context.StrictMode && context.HasErrors)
                    {
                        yield break;
                    }

                    context.SetPhase("Phase 2.5: Scene readiness");
                    SceneReadinessResult readiness = null;
                    yield return SceneReadiness.WaitUntilReady(
                        SceneLoader.Instance.CurrentScene,
                        isCancellationRequested,
                        value => readiness = value);

                    if (readiness?.Cancelled == true)
                    {
                        result.Cancelled = true;
                        yield break;
                    }

                    if (readiness?.Success != true)
                    {
                        context.Error(readiness?.Error ?? "Scene readiness did not return a result.");
                        yield break;
                    }

                    if (ShouldCancel(isCancellationRequested, result, context))
                    {
                        yield break;
                    }

                    yield return SnapshotRestore.RestoreAnchor(preparation.Snapshot, context);
                    if (!context.StrictMode || !context.HasErrors)
                    {
                        context.SetPhase("Postflight validation");
                        ValidateRestoredRuntime(preparation, context);
                    }

                    result.Success = !context.HasErrors;
                    if (result.Success)
                    {
                        result.RestoredTalkScene = preparation.TargetTalkScene;
                    }
                }
                finally
                {
                    IsRestoring = false;
                    AddRestoreLog("Restore finished");
                    result.Success = result.Success && !result.Cancelled && !context.HasErrors;
                    result.FailedPhase = result.Success || result.Cancelled ? null : context.CurrentPhase;
                    result.Errors = new List<string>(context.Errors);
                    result.Warnings = new List<string>(context.Warnings);
                    result.Log = new List<string>(_lastRestoreLog);
                }
            }
        }

        public static IDisposable SuppressAutoSaveScope(string reason)
        {
            _autoSaveSuppressDepth++;
            Debug.Log($"[SaveRestoreOrchestrator] SuppressAutoSave begin: {reason}, depth={_autoSaveSuppressDepth}");
            return new AutoSaveSuppressScope(reason);
        }

        private static RestorePreparation PrepareSnapshot(
            SaveSnapshot snapshot,
            string sourceLabel,
            TalkSceneGraphIndex talkSceneIndex,
            RestoreOptions options)
        {
            options ??= RestoreOptions.Default;
            var preparation = new RestorePreparation
            {
                Snapshot = snapshot,
                SourceLabel = sourceLabel,
                Options = options,
                Result = new RestoreResult()
            };

            var errors = new List<string>();
            if (snapshot == null)
                errors.Add("Snapshot is null.");
            else
            {
                if (snapshot.schemaVersion != SaveSnapshotSchema.CurrentVersion)
                    errors.Add($"Unsupported schema {snapshot.schemaVersion}; expected {SaveSnapshotSchema.CurrentVersion}.");
                if (string.IsNullOrWhiteSpace(snapshot.scene?.sceneName))
                    errors.Add("Snapshot scene is missing.");
                if (string.IsNullOrWhiteSpace(snapshot.anchor?.sceneSoName))
                    errors.Add("Snapshot TalkSceneSO is missing.");
                if (string.IsNullOrWhiteSpace(snapshot.anchor?.yarnProjectId))
                    errors.Add("Snapshot YarnProject is missing.");
            }

            TalkSceneSO targetScene = null;
            if (errors.Count == 0
                && !talkSceneIndex.TryFindByName(snapshot.anchor.sceneSoName, out targetScene, out var lookupError))
            {
                errors.Add(lookupError);
            }

            if (errors.Count == 0
                && (targetScene.yarnProject == null
                    || !string.Equals(
                        targetScene.yarnProject.name,
                        snapshot.anchor.yarnProjectId,
                        StringComparison.Ordinal)))
            {
                errors.Add($"TalkSceneSO YarnProject mismatch: {snapshot.anchor.yarnProjectId}.");
            }

            if (errors.Count == 0
                && !string.IsNullOrWhiteSpace(snapshot.anchor.nodeName)
                && !Array.Exists(
                    targetScene.yarnProject.NodeNames,
                    node => string.Equals(node, snapshot.anchor.nodeName, StringComparison.Ordinal)))
            {
                errors.Add($"Yarn node does not exist: {snapshot.anchor.nodeName}.");
            }

            if (errors.Count > 0)
            {
                preparation.Result = new RestoreResult
                {
                    Success = false,
                    FailedPhase = "Preflight",
                    Errors = errors
                };
                return preparation;
            }

            preparation.TargetTalkScene = targetScene;
            preparation.Result.Success = true;
            preparation.Result.RestoredTalkScene = targetScene;
            return preparation;
        }

        private static RestorePreparation FailedPreparation(
            string sourceLabel,
            string phase,
            string error,
            RestoreOptions options)
        {
            return new RestorePreparation
            {
                SourceLabel = sourceLabel,
                Options = options ?? RestoreOptions.Default,
                Result = RestoreResult.CreateFailure(phase, error)
            };
        }

        private static bool ShouldCancel(
            Func<bool> isCancellationRequested,
            RestoreResult result,
            SnapshotRestoreContext context)
        {
            if (isCancellationRequested?.Invoke() != true)
            {
                return false;
            }

            result.Cancelled = true;
            context.Log("Restore cancelled between phases.");
            return true;
        }

        private static void ValidateRestoredRuntime(
            RestorePreparation preparation,
            SnapshotRestoreContext context)
        {
            var snapshot = preparation.Snapshot;
            var sceneLoader = SceneLoader.Instance;
            if (sceneLoader == null || sceneLoader.IsLoading)
                context.Error("SceneLoader is not ready.");
            else if (!string.Equals(sceneLoader.CurrentSceneName, snapshot.scene.sceneName, StringComparison.Ordinal))
                context.Error($"Scene mismatch: {sceneLoader.CurrentSceneName ?? "none"}.");

            var targetScene = preparation.TargetTalkScene;
            if (!string.Equals(targetScene?.name, snapshot.anchor.sceneSoName, StringComparison.Ordinal))
                context.Error($"TalkSceneSO mismatch: {targetScene?.name ?? "none"}.");

            var runner = DialogController.Instance?.DialogueRunner;
            if (!string.Equals(runner?.YarnProject?.name, snapshot.anchor.yarnProjectId, StringComparison.Ordinal))
                context.Error($"YarnProject mismatch: {runner?.YarnProject?.name ?? "none"}.");
            if (!string.IsNullOrEmpty(snapshot.anchor.nodeName) && runner != null && !runner.IsDialogueRunning)
                context.Error($"Yarn node did not start: {snapshot.anchor.nodeName}.");

            if (snapshot.sections != null
                && snapshot.sections.ContainsKey(SnapshotProviderIds.Fix)
                && (FixSystem.FixSystemCenter.Instance == null
                    || !FixSystem.FixSystemCenter.Instance.IsDirectorReady))
            {
                context.Error("FixSystem is not ready.");
            }
        }

        private static void ResetRestoreLog(string sourceLabel)
        {
            _lastRestoreLog.Clear();
            AddRestoreLog($"Restore source: {sourceLabel}");
        }

        private static void AddRestoreLog(string message)
        {
            _lastRestoreLog.Add($"[{DateTime.Now:HH:mm:ss}] {message}");
            Debug.Log($"[SaveRestoreOrchestrator] {message}");
        }

        private sealed class AutoSaveSuppressScope : IDisposable
        {
            private readonly string _reason;
            private bool _disposed;

            public AutoSaveSuppressScope(string reason)
            {
                _reason = reason;
            }

            public void Dispose()
            {
                if (_disposed)
                {
                    return;
                }

                _disposed = true;
                _autoSaveSuppressDepth = Math.Max(0, _autoSaveSuppressDepth - 1);
                Debug.Log(
                    $"[SaveRestoreOrchestrator] SuppressAutoSave end: {_reason}, depth={_autoSaveSuppressDepth}");
            }
        }
    }
}