using System;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    public readonly struct AnchorCaptureSpec
    {
        public string SceneSoName { get; }
        public string YarnProjectId { get; }
        public string NodeName { get; }
        public bool StartDialogueOnRestore { get; }

        public AnchorCaptureSpec(
            string sceneSoName,
            string yarnProjectId,
            string nodeName,
            bool startDialogueOnRestore)
        {
            SceneSoName = sceneSoName;
            YarnProjectId = yarnProjectId;
            NodeName = nodeName;
            StartDialogueOnRestore = startDialogueOnRestore;
        }

        public bool IsComplete =>
            !string.IsNullOrWhiteSpace(SceneSoName)
            && !string.IsNullOrWhiteSpace(YarnProjectId)
            && !string.IsNullOrWhiteSpace(NodeName);
    }

    /// <summary>
    /// 从运行时组装 <see cref="SaveSnapshot"/>（纯内存，不写盘）。
    /// <para>
    /// 流程：元数据 → 场景 → 锚点（含宏观章节）→ Yarn 变量 → 各 Provider.Capture。
    /// scene / anchor 由框架直管；其余子系统通过 Provider 写入 sections。
    /// </para>
    /// </summary>
    public static class SnapshotCapture
    {
        /// <summary>捕获当前完整快照。调用前需已注册全部 provider。</summary>
        public static SaveSnapshot Capture(
            YarnVariableStorage storage,
            AnchorCaptureSpec anchorSpec)
        {
            if (!anchorSpec.IsComplete)
            {
                throw new ArgumentException(
                    "Snapshot anchor requires TalkScene, YarnProject and node name.",
                    nameof(anchorSpec));
            }

            SnapshotRegistry.ValidateRequiredProviders();

            var snapshot = new SaveSnapshot
            {
                gameVersion = Application.version,
                savedAt = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")
            };

            CaptureScene(snapshot);
            CaptureAnchor(snapshot, anchorSpec);
            CaptureYarnVariables(storage, snapshot);

            foreach (var provider in SnapshotRegistry.GetOrderedProviders())
            {
                var dto = provider.Capture();
                if (dto == null) continue;
                snapshot.sections[provider.SaveId] = dto;
            }

            snapshot.schemaVersion = SaveSnapshotSchema.CurrentVersion;
            return snapshot;
        }

        private static void CaptureScene(SaveSnapshot snapshot)
        {
            var sceneLoader = SceneLoader.Instance;
            snapshot.scene = new SceneSnapshotDto
            {
                sceneName = sceneLoader != null ? sceneLoader.CurrentSceneName : null
            };
        }

        private static void CaptureAnchor(SaveSnapshot snapshot, AnchorCaptureSpec anchorSpec)
        {
            snapshot.anchor = new AnchorSnapshot
            {
                sceneSoName = anchorSpec.SceneSoName,
                yarnProjectId = anchorSpec.YarnProjectId,
                nodeName = anchorSpec.NodeName,
                startDialogueOnRestore = anchorSpec.StartDialogueOnRestore
            };
        }

        private static void CaptureYarnVariables(YarnVariableStorage storage, SaveSnapshot snapshot)
        {
            var (floats, strings, bools) = storage.GetAllVariables();
            snapshot.yarnVariables = new YarnVariablesSnapshot
            {
                floats = floats ?? new(),
                strings = strings ?? new(),
                bools = bools ?? new()
            };
        }
    }
}