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

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 将 <see cref="SaveSnapshot"/> 逐项写回运行时（纯内存，不读盘）。
    /// <para>
    /// 顺序：Yarn 变量 → 场景加载 → 设置章节 → 各 Provider（按 RestoreOrder）→ 锚点加载对话并重进节点。
    /// 完整淡入淡出时序由 P4 在 <see cref="SaveRestoreOrchestrator"/> 扩展。
    /// </para>
    /// </summary>
    public static class SnapshotRestore
    {
        /// <summary>
        /// 还原 Yarn 变量、场景、章节与各 section；不包含锚点重进（由 <see cref="RestoreAnchor"/> 或上层编排）。
        /// </summary>
        public static IEnumerator Restore(YarnVariableStorage storage, SaveSnapshot snapshot)
        {
            if (snapshot == null)
            {
                Debug.LogError("[SnapshotRestore] snapshot 为 null");
                yield break;
            }

            RestoreYarnVariables(storage, snapshot);
            yield return RestoreScene(snapshot);
            RestoreSceneSo(snapshot);

            foreach (var provider in SnapshotRegistry.GetOrderedProviders())
            {
                if (!snapshot.sections.TryGetValue(provider.SaveId, out var dto) || dto == null)
                {
                    continue;
                }

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

            if (snapshot.deepRepair != null && snapshot.deepRepair.sections != null
                && snapshot.deepRepair.sections.Count > 0)
            {
                Debug.LogWarning("[SnapshotRestore] DeepRepair 段尚未实现，已跳过（P5）。");
            }
        }

        /// <summary>
        /// 按 <see cref="AnchorSnapshot"/> 加载对话工程并重新进入 Yarn 节点，实现「所见即所存」。
        /// 调用前应已完成场景加载与各 provider 还原。
        /// </summary>
        public static IEnumerator RestoreAnchor(SaveSnapshot snapshot)
        {
            if (snapshot?.anchor == null || string.IsNullOrEmpty(snapshot.anchor.nodeName))
            {
                yield break;
            }

            var dialog = DialogController.Instance;
            if (dialog == null) yield break;

            var runner = dialog.DialogueRunner;
            if (runner == null) yield break;

            // 若当前 Runner 未加载对应 YarnProject，则先加载
            if (!string.IsNullOrEmpty(snapshot.anchor.yarnProjectId))
            {
                var sceneSo = GameManager.Instance?.GetCurrentTalkSceneSo();
                if (sceneSo?.yarnProject != null && sceneSo.yarnProject.name == snapshot.anchor.yarnProjectId)
                {
                    if (runner.YarnProject == null || runner.YarnProject.name != snapshot.anchor.yarnProjectId)
                    {
                        dialog.LoadDialog(sceneSo.yarnProject);
                    }
                }
                else if (runner.YarnProject != null && runner.YarnProject.name != snapshot.anchor.yarnProjectId)
                {
                    Debug.LogWarning(
                        $"[SnapshotRestore] YarnProject 不匹配：当前 {runner.YarnProject.name}，存档 {snapshot.anchor.yarnProjectId}");
                }
            }

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

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

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

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

        private static IEnumerator RestoreScene(SaveSnapshot snapshot)
        {
            if (snapshot.scene == null || string.IsNullOrEmpty(snapshot.scene.sceneName))
            {
                yield break;
            }

            var sceneLoader = SceneLoader.Instance;
            if (sceneLoader == null)
            {
                Debug.LogError("[SnapshotRestore] SceneLoader 未初始化，无法加载场景");
                yield break;
            }

            yield return sceneLoader.LoadSceneAsync(snapshot.scene.sceneName);
        }

        private static void RestoreSceneSo(SaveSnapshot snapshot)
        {
            if (snapshot.anchor == null || string.IsNullOrEmpty(snapshot.anchor.sceneSoName))
            {
                return;
            }

            var gameManager = GameManager.Instance;
            if (gameManager == null)
            {
                Debug.LogWarning("[SnapshotRestore] GameManager 未初始化，无法设置章节 SO");
                return;
            }

            gameManager.SetSceneSoByName(snapshot.anchor.sceneSoName);
        }

        /// <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.Fix => jobj.ToObject<FixSnapshotDto>(),
                SnapshotProviderIds.Screen => jobj.ToObject<ScreenSnapshotDto>(),
                _ => jobj
            };
        }
    }
}