using Godot;
using System.Collections.Generic;
using System.Text.Json;

public static class SaveGameManager
{
    private const string SaveDirectory = "user://savegame";
    private const string GameDataPath = SaveDirectory + "/gamedata.json";
    private const string RobotsPath = SaveDirectory + "/robots.json";
    private const string ResearchPath = SaveDirectory + "/research.json";
    private const string LayerPrefix = SaveDirectory + "/layer_";
    private const string JsonExtension = ".json";

    private static readonly JsonSerializerOptions JsonOptions = new JsonSerializerOptions
    {
        WriteIndented = true
    };

    public static bool SaveExists()
    {
        return FileAccess.FileExists(GameDataPath);
    }

    public static void SaveGame()
    {
        SaveGameData saveGame = CreateSaveData();
        CreateSaveDirectory();
        ClearOldLayerFiles();

        SaveJson(GameDataPath, SaveGameDataFactory.CreateCoreSaveData(saveGame));
        SaveJson(RobotsPath, saveGame.Robots);
        SaveJson(ResearchPath, saveGame.Research);

        foreach (LayerSaveData layer in saveGame.Layers)
        {
            SaveJson(GetLayerPath(layer.Level), layer);
        }
    }

    public static SaveGameData LoadSaveData()
    {
        if (!SaveExists()) return null;

        SaveGameData saveGame = LoadJson<SaveGameData>(GameDataPath);
        if (saveGame == null) return null;

        saveGame.Robots = LoadJson<List<RobotSaveData>>(RobotsPath) ?? new List<RobotSaveData>();
        saveGame.Research = LoadJson<List<ResearchSaveData>>(ResearchPath) ?? new List<ResearchSaveData>();
        saveGame.Layers = LoadLayerSaveData();

        return saveGame;
    }

    public static SaveGameData CreateSaveData()
    {
        return SaveGameDataFactory.CreateSaveData();
    }

    public static void ApplyWorldData(SaveGameData saveGame)
    {
        SaveGameDataApplier.ApplyWorldData(saveGame);
    }

    private static List<LayerSaveData> LoadLayerSaveData()
    {
        List<LayerSaveData> result = new List<LayerSaveData>();

        for (int i = 0; i < GameData.ruinSize; i++)
        {
            string path = GetLayerPath(i);
            if (!FileAccess.FileExists(path)) continue;

            LayerSaveData layer = LoadJson<LayerSaveData>(path);
            if (layer != null)
            {
                result.Add(layer);
            }
        }

        return result;
    }

    private static string GetLayerPath(int level)
    {
        return LayerPrefix + level + JsonExtension;
    }

    private static void CreateSaveDirectory()
    {
        DirAccess.MakeDirRecursiveAbsolute(SaveDirectory);
    }

    private static void ClearOldLayerFiles()
    {
        DirAccess directory = DirAccess.Open(SaveDirectory);
        if (directory == null) return;

        directory.ListDirBegin();
        while (true)
        {
            string fileName = directory.GetNext();
            if (fileName == "") break;
            if (directory.CurrentIsDir()) continue;
            if (!fileName.StartsWith("layer_") || !fileName.EndsWith(JsonExtension)) continue;

            directory.Remove(fileName);
        }
        directory.ListDirEnd();
    }

    private static void SaveJson<T>(string path, T data)
    {
        string json = JsonSerializer.Serialize(data, JsonOptions);
        FileAccess file = FileAccess.Open(path, FileAccess.ModeFlags.Write);
        if (file == null) return;

        file.StoreString(json);
        file.Flush();
    }

    private static T LoadJson<T>(string path)
    {
        if (!FileAccess.FileExists(path)) return default;

        FileAccess file = FileAccess.Open(path, FileAccess.ModeFlags.Read);
        if (file == null) return default;

        string json = file.GetAsText();
        return JsonSerializer.Deserialize<T>(json);
    }
}