using System.Collections;
using Newtonsoft.Json.Linq;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 将 <see cref="SaveSnapshot"/> 按 Phase + Barrier 写回运行时（纯内存，不读盘）。
    /// </summary>
    public static class SnapshotRestore
    {
        /// <summary>
        /// Phase 0~2：Yarn 变量、场景、章节与所有 Provider；不包含锚点重进。
        /// </summary>
        public static IEnumerator RestoreState(
            YarnVariableStorage storage,
            SaveSnapshot snapshot,
            SnapshotRestoreContext context,
            System.Func<bool> isCancellationRequested = null)
        {
            if (snapshot == null)
            {
                context?.Error("snapshot 为 null");
                yield break;
            }

            context ??= new SnapshotRestoreContext(snapshot);

            context.SetPhase("Phase 0: Restore Yarn variables");
            RestoreYarnVariables(storage, snapshot);
            if (IsCancellationRequested(isCancellationRequested, context)) yield break;

            context.SetPhase("Phase 1: Load scene");
            yield return RestoreScene(snapshot, context);
            if (IsCancellationRequested(isCancellationRequested, context)) yield break;
            if (context.StrictMode && context.HasErrors) yield break;

            context.SetPhase("Phase 2: Restore providers (ordered by RestoreOrder)");
            yield return RestoreProvidersInOrder(snapshot, context, isCancellationRequested);
        }

        /// <summary>
        /// Phase 3：按 <see cref="AnchorSnapshot"/> 加载对话工程；若有节点名则重新进入 Yarn 节点。
        /// </summary>
        public static IEnumerator RestoreAnchor(SaveSnapshot snapshot, SnapshotRestoreContext context = null)
        {
            if (snapshot?.anchor == null)
            {
                context?.Log("Phase 3: No anchor, skip RestoreAnchor");
                yield break;
            }

            context ??= new SnapshotRestoreContext(snapshot);

            var hasNode = !string.IsNullOrEmpty(snapshot.anchor.nodeName);
            context.SetPhase(hasNode
                ? $"Phase 3: Restore anchor {snapshot.anchor.nodeName}"
                : "Phase 3: No anchor node, restore YarnProject only");

            var dialog = DialogController.Instance;
            if (dialog == null)
            {
                context.Warn("DialogController 未初始化，无法恢复 Yarn 状态。");
                yield break;
            }

            var runner = dialog.DialogueRunner;
            if (runner == null)
            {
                context.Warn("DialogueRunner 未初始化，无法恢复 Yarn 状态。");
                yield break;
            }

            if (!string.IsNullOrEmpty(snapshot.anchor.yarnProjectId))
            {
                var sceneSo = context.TargetTalkScene;
                if (sceneSo?.yarnProject == null)
                {
                    context.Error($"章节 {snapshot.anchor.sceneSoName} 没有可用的 YarnProject。");
                    yield break;
                }

                if (sceneSo.yarnProject.name != snapshot.anchor.yarnProjectId)
                {
                    context.Error(
                        $"章节 YarnProject 不匹配：章节 {sceneSo.yarnProject.name}，存档 {snapshot.anchor.yarnProjectId}");
                    yield break;
                }

                if (runner.YarnProject == null || runner.YarnProject.name != snapshot.anchor.yarnProjectId)
                {
                    dialog.LoadDialog(sceneSo.yarnProject);
                }
            }

            if (!hasNode)
            {
                yield break;
            }

            if (runner.IsDialogueRunning)
            {
                yield return runner.Stop();
            }

            if (runner.YarnProject == null
                || !System.Array.Exists(runner.YarnProject.NodeNames, node => node == snapshot.anchor.nodeName))
            {
                context.Error(
                    $"YarnProject {runner.YarnProject?.name ?? "none"} 不包含节点 {snapshot.anchor.nodeName}。");
                yield break;
            }

            yield return runner.StartDialogue(snapshot.anchor.nodeName);
        }

        private static void RestoreYarnVariables(YarnVariableStorage storage, SaveSnapshot snapshot)
        {
            var vars = snapshot.yarnVariables;
            if (vars == null || storage == null) return;

            storage.SetAllVariables(vars.floats, vars.strings, vars.bools);
        }

        private static IEnumerator RestoreScene(SaveSnapshot snapshot, SnapshotRestoreContext context)
        {
            if (snapshot.scene == null || string.IsNullOrEmpty(snapshot.scene.sceneName))
            {
                context.Warn("快照缺少 scene.sceneName，跳过场景加载。");
                yield break;
            }

            var sceneLoader = SceneLoader.Instance;
            if (sceneLoader == null)
            {
                context.Error("SceneLoader 未初始化，无法加载场景。");
                yield break;
            }

            SceneOperationResult result = null;
            yield return sceneLoader.LoadSceneAsync(
                snapshot.scene.sceneName,
                value => result = value);

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

            // 再等一帧，等Awake执行完
            yield return null;
        }

        /// <summary>
        /// 按 <see cref="ISnapshotProvider.RestoreOrder"/> 依次还原；
        /// 同步 Provider 连续调用，异步 Provider 作为 Barrier 挂起，二者混排而非分两批。
        /// </summary>
        private static IEnumerator RestoreProvidersInOrder(
            SaveSnapshot snapshot,
            SnapshotRestoreContext context,
            System.Func<bool> isCancellationRequested)
        {
            foreach (var provider in SnapshotRegistry.GetOrderedProviders())
            {
                if (IsCancellationRequested(isCancellationRequested, context))
                {
                    yield break;
                }

                if (!TryGetSectionDto(snapshot, provider, context, out var dto))
                {
                    continue;
                }

                switch (provider)
                {
                    case ISyncSnapshotProvider syncProvider:
                        context.Log($"Sync provider [{provider.RestoreOrder}]: {provider.SaveId}");
                        syncProvider.Restore(dto, context);
                        break;

                    case IAsyncSnapshotProvider asyncProvider:
                        context.Log($"Async provider [{provider.RestoreOrder}]: {provider.SaveId}");
                        yield return asyncProvider.RestoreAsync(dto, context);
                        break;

                    default:
                        context.Warn($"Provider {provider.SaveId} 未实现同步或异步还原契约，已跳过。");
                        break;
                }

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

                if (IsCancellationRequested(isCancellationRequested, context))
                {
                    yield break;
                }
            }
        }

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

            context.Log("Restore cancellation requested between phases.");
            return true;
        }

        private static bool TryGetSectionDto(
            SaveSnapshot snapshot,
            ISnapshotProvider provider,
            SnapshotRestoreContext context,
            out object dto)
        {
            dto = null;
            if (snapshot.sections == null
                || !snapshot.sections.TryGetValue(provider.SaveId, out dto)
                || dto == null)
            {
                context.Log($"Provider {provider.SaveId}: no section, skip");
                return false;
            }

            dto = CoerceSectionDto(provider.SaveId, dto);
            return true;
        }

        /// <summary>
        /// 读盘后 <see cref="SaveSnapshot.sections"/> 中的值常为 <see cref="JObject"/>；
        /// 按 SaveId 转回各 Provider 所需的强类型 DTO。
        /// </summary>
        private static object CoerceSectionDto(string saveId, object dto)
        {
            if (dto is not JObject jobj)
            {
                return dto;
            }

            return saveId switch
            {
                SnapshotProviderIds.Environment => jobj.ToObject<EnvironmentSnapshotDto>(),
                SnapshotProviderIds.Actor => jobj.ToObject<ActorSnapshotDto>(),
                SnapshotProviderIds.Audio => jobj.ToObject<AudioSnapshotDto>(),
                SnapshotProviderIds.Timeline => jobj.ToObject<TimelineSnapshotDto>(),
                SnapshotProviderIds.Subway => jobj.ToObject<SubwaySnapshotDto>(),
                SnapshotProviderIds.PunchTape => jobj.ToObject<PunchTapeSnapshotDto>(),
                SnapshotProviderIds.Fix => jobj.ToObject<FixSnapshotDto>(),
                SnapshotProviderIds.FixPanel => jobj.ToObject<FixPanelSnapshotDto>(),
                SnapshotProviderIds.BodyModule => jobj.ToObject<BodyModuleSnapshotDto>(),
                SnapshotProviderIds.Eye => jobj.ToObject<EyeSnapshotDto>(),
                SnapshotProviderIds.Showcase => jobj.ToObject<ShowcaseSnapshotDto>(),
                SnapshotProviderIds.Day2SleepPresentation => jobj.ToObject<Day2SleepPresentationSnapshotDto>(),
                SnapshotProviderIds.PlayTool => jobj.ToObject<PlayToolSnapshotDto>(),
                SnapshotProviderIds.Screen => jobj.ToObject<ScreenSnapshotDto>(),
                _ => jobj
            };
        }
    }
}