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;

        public static IReadOnlyList<string> LastRestoreLog => _lastRestoreLog;

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

        private const float RestoreFadeDuration = 0.2f;

        /// <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();

            if (TestSaveArchive.IsEnabled)
            {
                TestSaveArchive.Archive(snapshot, thumbnail);
                Debug.Log("[SaveRestoreOrchestrator] 测试存档模式：已写入 testsavs（不覆盖 slot_0）。");
                _isAutoSaving = false;
            }
            else
            {
                _ = 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);
        }

        /// <summary>从指定槽位读档并还原。</summary>
        public static IEnumerator RestoreFromSlot(int slotIndex)
        {
            var snapshot = SlotManager.LoadSnapshot(slotIndex);
            if (snapshot == null)
            {
                Debug.LogError($"[SaveRestoreOrchestrator] 槽位 {slotIndex} 不存在或读取失败");
                yield break;
            }

            yield return RestoreSnapshot(snapshot, $"slot_{slotIndex}");
        }

        /// <summary>从文件读档并还原；自动区分新快照格式与 legacy 格式。</summary>
        public static IEnumerator RestoreFromFile(string savePath)
        {
            yield return RestoreFromFile(savePath, RestoreOptions.Default, null);
        }

        /// <summary>从文件恢复并返回结构化结果；开发跳转使用严格校验和完整会话清理。</summary>
        public static IEnumerator RestoreFromFile(
            string savePath,
            RestoreOptions options,
            Action<RestoreResult> completed)
        {
            options ??= RestoreOptions.Default;
            var result = new RestoreResult();

            bool isLegacy;
            try
            {
                isLegacy = SnapshotPersistence.IsLegacyFormat(savePath);
            }
            catch (Exception ex)
            {
                result.Success = false;
                result.FailedPhase = "LoadSnapshot";
                result.Errors = new[] { ex.Message };
                completed?.Invoke(result);
                yield break;
            }

            if (isLegacy)
            {
                if (options.StrictValidation)
                {
                    result.Success = false;
                    result.FailedPhase = "Preflight";
                    result.Errors = new[] { "legacy format is not supported by strict restore" };
                    completed?.Invoke(result);
                    yield break;
                }

                Debug.LogWarning("[SaveRestoreOrchestrator] 检测到旧格式存档，请使用新快照格式重新保存。");
                yield return RestoreLegacyWithFlow(savePath);
                result.Success = true;
                result.Log = new List<string>(_lastRestoreLog);
                completed?.Invoke(result);
                yield break;
            }

            SaveSnapshot snapshot = null;
            try
            {
                using (new CodeTimer("LoadSnapshot"))
                {
                    snapshot = SnapshotPersistence.Load(savePath);
                }
            }
            catch (Exception ex)
            {
                result.Success = false;
                result.FailedPhase = "LoadSnapshot";
                result.Errors = new[] { ex.Message };
                completed?.Invoke(result);
                yield break;
            }

            yield return RestoreSnapshot(snapshot, savePath, options, result);
            completed?.Invoke(result);
        }

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

        /// <summary>旧档：仅恢复 Yarn 变量，再 Capture 写入 slot_0 完成格式迁移。</summary>
        private static IEnumerator RestoreLegacy(string savePath)
        {
            var saveData = SnapshotPersistence.ReadLegacySaveRoot(savePath);
            var floatDict = saveData["floatDict"]?.ToObject<Dictionary<string, float>>();
            var stringDict = saveData["stringDict"]?.ToObject<Dictionary<string, string>>();
            var boolDict = saveData["boolDict"]?.ToObject<Dictionary<string, bool>>();
            YarnVariableStorage.Instance.SetAllVariables(floatDict, stringDict, boolDict);

            if (saveData["systemData"] != null)
            {
                Debug.LogWarning(
                    "[SaveRestoreOrchestrator] 旧档 systemData 段已无法还原（IData 已移除）；" +
                    "仅恢复 Yarn 变量并迁移为新快照格式。");
            }

            var snapshot = SnapshotService.Capture();
            SlotManager.SaveToAutoSlot(snapshot, null);
            yield break;
        }

        private static IEnumerator RestoreLegacyWithFlow(string savePath)
        {
            using (SuppressAutoSaveScope("RestoreLegacy"))
            {
                IsRestoring = true;
                ResetRestoreLog("legacy");

                try
                {
                    PrepareGameSessionForRestore();
                    yield return FadeInForRestore();
                    yield return RestoreLegacy(savePath);
                    yield return null;
                    FinalizeGameSessionAfterRestore();
                    yield return FadeOutForRestore();
                    ScreenSnapshotHelper.ApplyDeferredFadeScreenIfNeeded();
                }
                finally
                {
                    IsRestoring = false;
                    AddRestoreLog("Legacy restore finished");
                }
            }
        }

        private static IEnumerator RestoreSnapshot(SaveSnapshot snapshot, string sourceLabel)
        {
            yield return RestoreSnapshot(snapshot, sourceLabel, RestoreOptions.Default, new RestoreResult());
        }

        private static IEnumerator RestoreSnapshot(
            SaveSnapshot snapshot,
            string sourceLabel,
            RestoreOptions options,
            RestoreResult result)
        {
            if (snapshot == null)
            {
                Debug.LogError("[SaveRestoreOrchestrator] snapshot 为 null，无法读档。");
                result.Success = false;
                result.FailedPhase = "Preflight";
                result.Errors = new[] { "snapshot is null" };
                yield break;
            }

            using (SuppressAutoSaveScope($"RestoreSnapshot:{sourceLabel}"))
            {
                IsRestoring = true;
                ResetRestoreLog(sourceLabel);
                var context = new SnapshotRestoreContext(
                    snapshot,
                    strictMode: options.StrictValidation,
                    logStep: AddRestoreLog);

                try
                {
                    context.SetPhase("Preflight");
                    ValidateSnapshotForRestore(snapshot, context);
                    if (context.StrictMode && context.HasErrors)
                    {
                        yield break;
                    }

                    if (options.CleanSessionFirst && GameManager.Instance != null)
                    {
                        context.SetPhase("Clean game session");
                        yield return GameManager.Instance.ResetGameSessionRoutine();
                    }

                    PrepareGameSessionForRestore();

                    yield return FadeInForRestore();

                    SnapshotRegistry.EnsureInitialized();
                    yield return SnapshotRestore.RestoreState(YarnVariableStorage.Instance, snapshot, context);
                    if (!context.StrictMode || !context.HasErrors)
                    {
                        yield return SnapshotRestore.RestoreAnchor(snapshot, context);
                    }

                    if (!context.StrictMode || !context.HasErrors)
                    {
                        context.SetPhase("Phase 3.5: settle one frame");
                        yield return null;
                        ValidateRestoredRuntime(snapshot, context);
                    }

                    if (!context.StrictMode || !context.HasErrors)
                    {
                        FinalizeGameSessionAfterRestore();
                    }

                    yield return FadeOutForRestore();
                    ScreenSnapshotHelper.ApplyDeferredFadeScreenIfNeeded();
                }
                finally
                {
                    IsRestoring = false;
                    AddRestoreLog("Restore finished");
                    result.Success = !context.HasErrors;
                    result.FailedPhase = context.HasErrors ? context.CurrentPhase : null;
                    result.Errors = new List<string>(context.Errors);
                    result.Warnings = new List<string>(context.Warnings);
                    result.Log = new List<string>(_lastRestoreLog);
                }
            }
        }

        private static void ValidateSnapshotForRestore(SaveSnapshot snapshot, SnapshotRestoreContext context)
        {
            if (snapshot.schemaVersion != SaveSnapshotSchema.CurrentVersion)
                context.Error($"Unsupported schema {snapshot.schemaVersion}; expected {SaveSnapshotSchema.CurrentVersion}.");
            if (string.IsNullOrWhiteSpace(snapshot.scene?.sceneName))
                context.Error("Snapshot scene is missing.");
            if (string.IsNullOrWhiteSpace(snapshot.anchor?.sceneSoName))
                context.Error("Snapshot TalkSceneSO is missing.");
            if (string.IsNullOrWhiteSpace(snapshot.anchor?.yarnProjectId))
                context.Error("Snapshot YarnProject is missing.");
            if (string.IsNullOrWhiteSpace(snapshot.anchor?.nodeName))
                context.Error("Snapshot Yarn node is missing.");

            if (context.HasErrors) return;
            var sceneSo = GameManager.Instance?.FindSceneSoByName(snapshot.anchor.sceneSoName);
            if (sceneSo == null)
            {
                context.Error($"TalkSceneSO does not exist: {snapshot.anchor.sceneSoName}.");
                return;
            }
            if (sceneSo.yarnProject == null
                || !string.Equals(sceneSo.yarnProject.name, snapshot.anchor.yarnProjectId, StringComparison.Ordinal))
            {
                context.Error($"TalkSceneSO YarnProject mismatch: {snapshot.anchor.yarnProjectId}.");
                return;
            }
            if (!Array.Exists(sceneSo.yarnProject.NodeNames,
                    node => string.Equals(node, snapshot.anchor.nodeName, StringComparison.Ordinal)))
            {
                context.Error($"Yarn node does not exist: {snapshot.anchor.nodeName}.");
            }
        }

        private static void ValidateRestoredRuntime(SaveSnapshot snapshot, SnapshotRestoreContext context)
        {
            context.SetPhase("Postflight validation");
            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 sceneSo = GameManager.Instance?.GetCurrentTalkSceneSo();
            if (!string.Equals(sceneSo?.name, snapshot.anchor.sceneSoName, StringComparison.Ordinal))
                context.Error($"TalkSceneSO mismatch: {sceneSo?.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.");
            }
        }

        /// <summary>
        /// 读档前对齐「已进入游戏」的 UI 与输入状态。
        /// 编辑器测试工具等路径可能跳过 <see cref="GameLoopEnum.GameStart"/>，导致 TerminalPanel 未关闭、
        /// <see cref="GameManager.state.isInGame"/> 为 false，从而无法推进对话。
        /// </summary>
        private static void PrepareGameSessionForRestore()
        {
            AddRestoreLog("Prepare game session for restore");

            // 读档淡入使用 DOTween（受 timeScale 影响）；若处于暂停态须先恢复，否则 FadeIn 永不结束、画面卡在诊室/终端。
            Time.timeScale = 1f;

            var gameManager = GameManager.Instance;
            if (gameManager != null && !gameManager.state.isInGame)
            {
                EnumEventSystem.Global.Send(GameLoopEnum.GameStart);
            }

            var ui = UIManager.Instance;
            if (ui != null)
            {
                ui.HidePanel<TerminalPanel>();
                ui.HidePanel<InGameTerminalPanel>();
                ui.ShowPanel<MainPanel>();
                ui.HidePanel<SavesPanel>();
                ui.HidePanel<EndPanel>();
            }

            if (gameManager != null && gameManager.state.isInPause)
            {
                gameManager.ContinueGame();
            }
            else
            {
                DialogUIManager.Instance?.OpenCanvas();
            }
        }

        /// <summary>读档完成后确保对话 Canvas 可用、退出暂停态。</summary>
        private static void FinalizeGameSessionAfterRestore()
        {
            AddRestoreLog("Finalize game session after restore");

            DialogUIManager.Instance?.OpenCanvas();

            var gameManager = GameManager.Instance;
            if (gameManager != null && gameManager.state.isInPause)
            {
                gameManager.ContinueGame();
            }
        }

        private static IEnumerator FadeInForRestore()
        {
            AddRestoreLog("Begin restore fade in");
            var panel = UIManager.Instance?.GetPanel<PlayToolPanel>();
            if (panel != null)
            {
                yield return panel.FadeInAsync(RestoreFadeDuration, useUnscaledTime: true);
            }
        }

        private static IEnumerator FadeOutForRestore()
        {
            AddRestoreLog("End restore fade out");
            var panel = UIManager.Instance?.GetPanel<PlayToolPanel>();
            if (panel != null)
            {
                yield return panel.FadeOutAsync(RestoreFadeDuration, useUnscaledTime: true);
            }
        }

        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}");
            }
        }
    }
}