using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using AibisDream.Utility;
using Newtonsoft.Json;
using UnityEngine;

namespace AibisDream.SaveSystem
{
    /// <summary>
    /// 测试存档模式：每次自动存档写入 <see cref="ConstRef.TestAutoSaveArchivePath"/> 下的独立子目录。
    /// 开启后不写入 slot_0，存多少次就保留多少份，与正式 saves/ 完全隔离。
    /// </summary>
    public static class TestSaveArchive
    {
        public const string EditorPrefsEnabledKey = "AibisDream.SaveSystem.TestArchiveEnabled";

        /// <summary>测试存档模式是否开启（Editor 下由 EditorPrefs 控制，构建产物恒为 false）。</summary>
        public static bool IsEnabled
        {
            get
            {
#if UNITY_EDITOR
                return UnityEditor.EditorPrefs.GetBool(EditorPrefsEnabledKey, true);
#else
                return false;
#endif
            }
        }

        private static readonly object ArchiveWriteLock = new object();

        /// <summary>将快照写入 testsavs 新条目，返回文件夹名。每次调用均新建，不覆盖已有条目。</summary>
        public static string Archive(SaveSnapshot snapshot, byte[] thumbnailPng)
        {
            if (snapshot == null)
            {
                return null;
            }

            var entryId = BuildUniqueEntryId(snapshot);
            var entryDir = Path.Combine(ConstRef.TestAutoSaveArchivePath, entryId);
            Directory.CreateDirectory(entryDir);

            var json = SnapshotPersistence.Serialize(snapshot);
            var meta = BuildMeta(entryId, snapshot);

            lock (ArchiveWriteLock)
            {
                SlotAtomicWriter.WriteText(json, Path.Combine(entryDir, $"{ConstRef.SaveSnapshotFileName}.json"));
                SlotAtomicWriter.WriteJson(meta, Path.Combine(entryDir, $"{ConstRef.SaveMetaFileName}.json"));

                if (thumbnailPng != null)
                {
                    SlotAtomicWriter.WriteBytes(
                        thumbnailPng,
                        Path.Combine(entryDir, $"{ConstRef.SaveThumbnailFileName}.png"));
                }
            }

            Debug.Log($"[TestSaveArchive] 已归档测试存档: {entryId}");
            return entryId;
        }

        public static List<TestSaveArchiveEntry> ListEntries()
        {
            var result = new List<TestSaveArchiveEntry>();
            if (!Directory.Exists(ConstRef.TestAutoSaveArchivePath))
            {
                return result;
            }

            foreach (var dir in Directory.GetDirectories(ConstRef.TestAutoSaveArchivePath))
            {
                var entryId = Path.GetFileName(dir);
                var snapshotPath = Path.Combine(dir, $"{ConstRef.SaveSnapshotFileName}.json");
                if (!File.Exists(snapshotPath))
                {
                    continue;
                }

                var metaPath = Path.Combine(dir, $"{ConstRef.SaveMetaFileName}.json");
                var thumbPath = Path.Combine(dir, $"{ConstRef.SaveThumbnailFileName}.png");

                SlotMeta meta = null;
                if (File.Exists(metaPath))
                {
                    try
                    {
                        meta = JsonConvert.DeserializeObject<SlotMeta>(File.ReadAllText(metaPath));
                    }
                    catch (Exception ex)
                    {
                        Debug.LogWarning($"[TestSaveArchive] 读取 meta 失败 ({entryId}): {ex.Message}");
                    }
                }

                result.Add(new TestSaveArchiveEntry(
                    entryId,
                    dir,
                    snapshotPath,
                    File.Exists(thumbPath) ? thumbPath : null,
                    meta));
            }

            return result
                .OrderByDescending(e => e.Meta?.savedAt ?? string.Empty)
                .ThenByDescending(e => e.EntryId, StringComparer.Ordinal)
                .ToList();
        }

        public static void DeleteEntry(string entryId)
        {
            if (string.IsNullOrEmpty(entryId))
            {
                return;
            }

            var dir = Path.Combine(ConstRef.TestAutoSaveArchivePath, entryId);
            if (Directory.Exists(dir))
            {
                Directory.Delete(dir, recursive: true);
            }
        }

        public static void ClearAll()
        {
            if (!Directory.Exists(ConstRef.TestAutoSaveArchivePath))
            {
                return;
            }

            foreach (var dir in Directory.GetDirectories(ConstRef.TestAutoSaveArchivePath))
            {
                Directory.Delete(dir, recursive: true);
            }
        }

        private static string BuildUniqueEntryId(SaveSnapshot snapshot)
        {
            var baseId = BuildEntryId(snapshot);
            var entryId = baseId;
            var suffix = 2;

            while (Directory.Exists(Path.Combine(ConstRef.TestAutoSaveArchivePath, entryId)))
            {
                entryId = $"{baseId}_{suffix}";
                suffix++;
            }

            return entryId;
        }

        private static string BuildEntryId(SaveSnapshot snapshot)
        {
            var timestamp = DateTime.Now.ToString("yyyyMMdd_HHmmss_fff");
            var nodeName = snapshot.anchor?.nodeName;
            var safeNode = string.IsNullOrEmpty(nodeName) ? "no_node" : SanitizeEntryName(nodeName);
            return $"{timestamp}_{safeNode}";
        }

        private static SlotMeta BuildMeta(string entryId, SaveSnapshot snapshot)
        {
            var summary = SaveSnapshotSummary.From(snapshot);
            return new SlotMeta
            {
                slotIndex = -1,
                savedAt = snapshot.savedAt,
                sceneName = summary.SceneName,
                sceneSoName = summary.SceneSoName,
                yarnProjectId = summary.YarnProjectId,
                nodeName = snapshot.anchor?.nodeName,
                schemaVersion = snapshot.schemaVersion,
                gameVersion = snapshot.gameVersion,
                thumbnailFile = $"{ConstRef.SaveThumbnailFileName}.png"
            };
        }

        private static string SanitizeEntryName(string name)
        {
            foreach (var c in Path.GetInvalidFileNameChars())
            {
                name = name.Replace(c, '_');
            }

            if (name.Length > 48)
            {
                name = name.Substring(0, 48);
            }

            return string.IsNullOrWhiteSpace(name) ? "no_node" : name;
        }
    }

    public readonly struct TestSaveArchiveEntry
    {
        public readonly string EntryId;
        public readonly string DirectoryPath;
        public readonly string SnapshotPath;
        public readonly string ThumbnailPath;
        public readonly SlotMeta Meta;

        public TestSaveArchiveEntry(
            string entryId,
            string directoryPath,
            string snapshotPath,
            string thumbnailPath,
            SlotMeta meta)
        {
            EntryId = entryId;
            DirectoryPath = directoryPath;
            SnapshotPath = snapshotPath;
            ThumbnailPath = thumbnailPath;
            Meta = meta;
        }
    }
}