using System.Collections.Generic;
using Ichni.Menu;
using Ichni.Story;
using UnityEngine;

namespace Ichni
{
    /// <summary>
    /// 剧情存档模块。
    /// <para>故事树状态与对话选项 <b>按章节</b> 保存（单文件、单 ES3 key）。</para>
    /// <para>剧情变量 <b>全局</b> 保存，可跨章节引用，契合 Yarn 变量模型。</para>
    /// </summary>
    public class StorySaveModule
    {
        private const string ChapterStoryKey = "ChapterStory";
        private const string VariablesKey    = "StoryVariables";

        // 每个剧情存档文件都保存自己的 Schema Version；不要把它与歌曲成绩存档的 Version 混用。
        // 当前项目尚未正式发布，剧情存档统一从 v1 开始；非 v1 的测试存档会被直接重置。
        // 正式发布后升级 Schema 时，必须用非破坏性迁移替代当前的重置策略。
        private const string StorySaveSchemaVersionKey = "StorySaveSchemaVersion";
        private const int CurrentStorySaveSchemaVersion = 1;

        // 已加载章节的内存缓存（chapterIndex -> 章节存档）
        private readonly Dictionary<string, ChapterStorySave> _chapterSaves =
            new Dictionary<string, ChapterStorySave>();

        // 全局剧情变量（float / string / bool 三类型，匹配 Yarn 契约）
        public StoryVariablesSave variables = new StoryVariablesSave();

        private static string GetChapterSavePath(string chapterIndex) =>
            Application.persistentDataPath + "/StorySaves/" + chapterIndex + ".json";

        private static string VariablesPath =>
            Application.persistentDataPath + "/StorySaves/StoryVariables.json";

        /// <summary>
        /// 补齐章节存档的可空集合，并以文件名对应的 chapterIndex 作为唯一归属。
        /// 当前用于保证新建 v1 存档的运行时集合非空；未来迁移逻辑应单独实现，不应依赖此方法隐式转换。
        /// </summary>
        private static ChapterStorySave NormalizeChapterSave(ChapterStorySave save, string chapterIndex)
        {
            save ??= new ChapterStorySave();
            save.chapterIndex = chapterIndex;
            save.completedBlockIds ??= new List<string>();
            save.selectedChoices ??= new Dictionary<string, int>();
            return save;
        }

        /// <summary>
        /// 补齐全局剧情变量字典，保证新建 v1 存档可被 Yarn 变量访问。
        /// </summary>
        private static StoryVariablesSave NormalizeVariables(StoryVariablesSave storyVariables)
        {
            storyVariables ??= new StoryVariablesSave();
            storyVariables.floatVariables ??= new Dictionary<string, float>();
            storyVariables.stringVariables ??= new Dictionary<string, string>();
            storyVariables.boolVariables ??= new Dictionary<string, bool>();
            return storyVariables;
        }

        // ── 故事树 + 选项（按章节）────────────────────────────────────────────────

        /// <summary>
        /// 判断某章节是否尚无可用的 v1 存档（首次进入或旧测试存档待重置）。
        /// </summary>
        public bool IsNewChapter(string chapterIndex)
        {
            string path = GetChapterSavePath(chapterIndex);
            return !ES3.FileExists(path) || !ES3.KeyExists(ChapterStoryKey, path) ||
                   !ES3.KeyExists(StorySaveSchemaVersionKey, path) ||
                   ES3.Load<int>(StorySaveSchemaVersionKey, path) != CurrentStorySaveSchemaVersion;
        }

        /// <summary>
        /// 加载指定章节的 v1 存档容器；无存档或非 v1 的预发布测试存档会直接重置为空容器。
        /// 加载结果会写入内存缓存。
        /// </summary>
        public ChapterStorySave LoadChapter(string chapterIndex)
        {
            string path = GetChapterSavePath(chapterIndex);
            bool hasExistingFile = ES3.FileExists(path);
            int loadedSchemaVersion = hasExistingFile && ES3.KeyExists(StorySaveSchemaVersionKey, path)
                ? ES3.Load<int>(StorySaveSchemaVersionKey, path)
                : 0;

            if (hasExistingFile && loadedSchemaVersion != CurrentStorySaveSchemaVersion)
            {
                Debug.LogWarning($"Resetting pre-release chapter story save '{chapterIndex}' from schema v{loadedSchemaVersion} to v{CurrentStorySaveSchemaVersion}.");
                ES3.DeleteFile(path);
                hasExistingFile = false;
            }

            ChapterStorySave save = hasExistingFile && ES3.KeyExists(ChapterStoryKey, path)
                ? ES3.Load<ChapterStorySave>(ChapterStoryKey, path)
                : new ChapterStorySave();
            save = NormalizeChapterSave(save, chapterIndex);
            _chapterSaves[chapterIndex] = save;
            return save;
        }

        /// <summary>
        /// 保存整章存档（blocks + connectors + choices），单次 ES3 写入。
        /// </summary>
        public void SaveChapter(ChapterStorySave save)
        {
            if (save == null || string.IsNullOrEmpty(save.chapterIndex))
            {
                Debug.LogWarning("Cannot save a chapter story record without a chapterIndex.");
                return;
            }

            save = NormalizeChapterSave(save, save.chapterIndex);
            _chapterSaves[save.chapterIndex] = save;
            string path = GetChapterSavePath(save.chapterIndex);
            ES3.Save(ChapterStoryKey, save, path);
            ES3.Save(StorySaveSchemaVersionKey, CurrentStorySaveSchemaVersion, path);
        }

        /// <summary>
        /// 获取内存中的章节存档；若未加载则从磁盘加载。
        /// </summary>
        public ChapterStorySave GetChapter(string chapterIndex)
        {
            return _chapterSaves.TryGetValue(chapterIndex, out ChapterStorySave save)
                ? save
                : LoadChapter(chapterIndex);
        }

        // ── 对话选项（按章节）──────────────────────────────────────────────────────

        /// <summary>
        /// 记录某章节内一次对话选项的选择结果。
        /// </summary>
        public void SetChoice(string chapterIndex, string choiceKey, int optionIndex)
        {
            GetChapter(chapterIndex).selectedChoices[choiceKey] = optionIndex;
        }

        /// <summary>
        /// 读取某章节内已记录的对话选项选择结果。
        /// </summary>
        public bool TryGetChoice(string chapterIndex, string choiceKey, out int optionIndex)
        {
            return GetChapter(chapterIndex).selectedChoices.TryGetValue(choiceKey, out optionIndex);
        }

        // ── 剧情变量（全局）──────────────────────────────────────────────────────

        /// <summary>
        /// 从磁盘加载全局剧情变量（启动时调用）。
        /// </summary>
        public void LoadVariables()
        {
            bool hasExistingFile = ES3.FileExists(VariablesPath);
            int loadedSchemaVersion = hasExistingFile && ES3.KeyExists(StorySaveSchemaVersionKey, VariablesPath)
                ? ES3.Load<int>(StorySaveSchemaVersionKey, VariablesPath)
                : 0;

            if (hasExistingFile && loadedSchemaVersion != CurrentStorySaveSchemaVersion)
            {
                Debug.LogWarning($"Resetting pre-release global story variables from schema v{loadedSchemaVersion} to v{CurrentStorySaveSchemaVersion}.");
                ES3.DeleteFile(VariablesPath);
                hasExistingFile = false;
            }

            variables = hasExistingFile && ES3.KeyExists(VariablesKey, VariablesPath)
                ? ES3.Load<StoryVariablesSave>(VariablesKey, VariablesPath)
                : new StoryVariablesSave();
            variables = NormalizeVariables(variables);
        }

        /// <summary>
        /// 将全局剧情变量写入磁盘。
        /// </summary>
        public void SaveVariables()
        {
            variables = NormalizeVariables(variables);
            ES3.Save(VariablesKey, variables, VariablesPath);
            ES3.Save(StorySaveSchemaVersionKey, CurrentStorySaveSchemaVersion, VariablesPath);
        }

        // ── 清档 ────────────────────────────────────────────────────────────────

        /// <summary>
        /// 清除所有章节的故事树存档与全局剧情变量。
        /// </summary>
        public void ClearAllStoryline()
        {
            if (ChapterSelectionManager.instance != null)
            {
                foreach (ChapterSelectionUnit chapter in ChapterSelectionManager.instance.chapters)
                {
                    string path = GetChapterSavePath(chapter.chapterIndex);
                    if (ES3.FileExists(path))
                        ES3.DeleteFile(path);
                }
            }

            _chapterSaves.Clear();

            if (ES3.FileExists(VariablesPath))
                ES3.DeleteFile(VariablesPath);

            variables = new StoryVariablesSave();

            Debug.Log("Cleared all story saves (chapters + global variables).");
        }
    }
}