using System;
using UnityEngine;
using Yarn.Unity;

namespace AibisDream.SaveSystem
{
    /// <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>
        /// <param name="triggerNodeName">
        /// 触发存档时的 Yarn 节点名（通常为 <c>OnNodeStart</c> 传入值）。
        /// 非 null 时作为 anchor，并与 Capture 时刻的当前节点比较；不一致时打 warning，不阻断写盘。
        /// </param>
        /// <param name="omitAnchor">
        /// 为 true 时写入空 <see cref="AnchorSnapshot.nodeName"/>（显式 <c>&lt;&lt;save&gt;&gt;</c> 默认行为）。
        /// </param>
        public static SaveSnapshot Capture(
            YarnVariableStorage storage,
            string triggerNodeName = null,
            bool omitAnchor = false)
        {
            SnapshotRegistry.ValidateRequiredProviders();

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

            CaptureScene(snapshot);
            CaptureAnchor(snapshot, triggerNodeName, omitAnchor);
            CaptureYarnVariables(storage, snapshot);

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

            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, string triggerNodeName, bool omitAnchor)
        {
            var dialog = DialogController.Instance;
            if (dialog == null) return;

            string anchorNodeName;
            if (omitAnchor)
            {
                anchorNodeName = string.Empty;
            }
            else
            {
                var (currentNodeName, _) = dialog.GetCurrentNodeContext();
                anchorNodeName = triggerNodeName ?? currentNodeName ?? string.Empty;

                if (triggerNodeName != null
                    && !string.Equals(
                        NormalizeNodeName(triggerNodeName),
                        NormalizeNodeName(currentNodeName),
                        StringComparison.Ordinal))
                {
                    Debug.LogWarning(
                        $"[SnapshotCapture] 存档锚点漂移：触发时「{FormatNodeName(triggerNodeName)}」，" +
                        $"Capture 时「{FormatNodeName(currentNodeName)}」。anchor 使用触发节点。");
                }
            }

            var yarnProject = dialog.DialogueRunner?.YarnProject;
            var projectId = yarnProject != null ? yarnProject.name : string.Empty;

            var gameManager = GameManager.Instance;
            var sceneSoName = gameManager != null ? gameManager.GetSceneSoName() : null;

            snapshot.anchor = new AnchorSnapshot
            {
                sceneSoName = sceneSoName,
                yarnProjectId = projectId,
                nodeName = anchorNodeName
            };
        }

        private static string NormalizeNodeName(string nodeName)
        {
            return string.IsNullOrEmpty(nodeName) ? string.Empty : nodeName;
        }

        private static string FormatNodeName(string nodeName)
        {
            return string.IsNullOrEmpty(nodeName) ? "(无节点)" : nodeName;
        }

        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()
            };
        }
    }
}