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, 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 new SaveGameData
        {
            Seed = GameData.seed,
            CurrentLayer = GameData.currentLayer,
            VisibleLayer = GameData.visibleLayer,
            LowestLayer = GameData.lowestLayer,
            MaxRobotCount = GameData.maxRobotCount,
            CanMove = GameData.canMove,
            Survival = CreateSurvivalSaveData(),
            Inventory = CreateInventorySaveData(),
            Research = CreateResearchSaveData(),
            Layers = CreateLayerSaveData(),
            Robots = CreateRobotSaveData()
        };
    }

    public static void ApplyWorldData(SaveGameData saveGame)
    {
        if (saveGame == null) return;

        GameData.seed = saveGame.Seed;
        GameData.currentLayer = saveGame.CurrentLayer;
        GameData.visibleLayer = saveGame.VisibleLayer;
        GameData.lowestLayer = saveGame.LowestLayer;
        GameData.maxRobotCount = saveGame.MaxRobotCount;
        GameData.canMove = saveGame.CanMove;

        ApplySurvivalData(saveGame.Survival);
        ApplyInventoryData(saveGame.Inventory);
        ApplyResearchData(saveGame.Research);
        ApplyLayerData(saveGame.Layers);
    }

    private static SurvivalSaveData CreateSurvivalSaveData()
    {
        return new SurvivalSaveData
        {
            Hunger = GameData.survival.hunger,
            Thirst = GameData.survival.thirst,
            Energy = GameData.survival.energy,
            IsDead = GameData.survival.isDead,
            DeathReason = GameData.survival.deathReason,
            CurrentStatus = GameData.survival.currentStatus
        };
    }

    private static List<ItemSaveData> CreateInventorySaveData()
    {
        List<ItemSaveData> result = new List<ItemSaveData>();

        foreach (Item item in GameData.inventory.items)
        {
            result.Add(new ItemSaveData
            {
                Id = item.data.Id,
                Amount = item.currentAmount
            });
        }

        return result;
    }

    private static List<ResearchSaveData> CreateResearchSaveData()
    {
        List<ResearchSaveData> result = new List<ResearchSaveData>();

        foreach (Research research in GameData.availableResearch.Values)
        {
            result.Add(new ResearchSaveData
            {
                Id = research.data.Id,
                State = research.state,
                ElapsedResearchTime = research.elapsedResearchTime,
                PaidResources = research.paidResources
            });
        }

        return result;
    }

    private static List<LayerSaveData> CreateLayerSaveData()
    {
        List<LayerSaveData> result = new List<LayerSaveData>();
        if (GameData.map == null) return result;

        foreach (Layer layer in GameData.map)
        {
            if (layer == null) continue;

            result.Add(new LayerSaveData
            {
                Level = layer.level,
                IsGateOpen = layer.isGateOpen,
                HasContentGenerated = layer.hasContentGenerated,
                GateIngredients = new List<Ingredient>(layer.gateIngredients),
                CurrentResources = new List<string>(layer.currentResources),
                Tiles = CreateTileSaveData(layer)
            });
        }

        return result;
    }

    private static List<TileSaveData> CreateTileSaveData(Layer layer)
    {
        List<TileSaveData> result = new List<TileSaveData>();

        foreach (Tile tile in layer.tiles)
        {
            result.Add(new TileSaveData
            {
                X = tile.GridPosition.X,
                Y = tile.GridPosition.Y,
                CollapsedMesh = tile.collapsedMesh,
                ContainsLight = tile.containsLight,
                ContainsDecoration = tile.containsDecoration,
                ContainsResource = tile.containsResource,
                WasVisited = tile.wasVisited,
                Resource = tile.resource == null ? null : tile.resource.CreateSaveData()
            });
        }

        return result;
    }

    private static List<RobotSaveData> CreateRobotSaveData()
    {
        List<RobotSaveData> result = new List<RobotSaveData>();

        foreach (Robot robot in GameData.robots)
        {
            result.Add(robot.CreateSaveData());
        }

        return result;
    }

    private static SaveGameData CreateCoreSaveData(SaveGameData saveGame)
    {
        return new SaveGameData
        {
            Seed = saveGame.Seed,
            CurrentLayer = saveGame.CurrentLayer,
            VisibleLayer = saveGame.VisibleLayer,
            LowestLayer = saveGame.LowestLayer,
            MaxRobotCount = saveGame.MaxRobotCount,
            CanMove = saveGame.CanMove,
            Survival = saveGame.Survival,
            Inventory = saveGame.Inventory,
            Research = new List<ResearchSaveData>(),
            Layers = new List<LayerSaveData>(),
            Robots = new List<RobotSaveData>()
        };
    }

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

    private static void ApplySurvivalData(SurvivalSaveData survival)
    {
        if (survival == null) return;

        GameData.survival.hunger = survival.Hunger;
        GameData.survival.thirst = survival.Thirst;
        GameData.survival.energy = survival.Energy;
        GameData.survival.isDead = survival.IsDead;
        GameData.survival.deathReason = survival.DeathReason ?? "";
        GameData.survival.currentStatus = survival.CurrentStatus ?? "";
    }

    private static void ApplyInventoryData(List<ItemSaveData> savedItems)
    {
        GameData.inventory = new Inventory();
        if (savedItems == null) return;

        foreach (ItemSaveData savedItem in savedItems)
        {
            if (!GameData.availableItems.ContainsKey(savedItem.Id)) continue;

            GameData.inventory.AddItem(
                new Item { data = GameData.availableItems[savedItem.Id] },
                savedItem.Amount
            );
        }
    }

    private static void ApplyResearchData(List<ResearchSaveData> savedResearch)
    {
        if (savedResearch == null) return;

        foreach (ResearchSaveData savedState in savedResearch)
        {
            if (!GameData.availableResearch.ContainsKey(savedState.Id)) continue;

            Research research = GameData.availableResearch[savedState.Id];
            research.state = savedState.State;
            research.elapsedResearchTime = savedState.ElapsedResearchTime;
            research.paidResources = savedState.PaidResources;
        }

        GameData.RebuildRobotStatsFromResearch();
    }

    private static void ApplyLayerData(List<LayerSaveData> savedLayers)
    {
        if (savedLayers == null || GameData.map == null) return;

        foreach (LayerSaveData savedLayer in savedLayers)
        {
            if (savedLayer.Level < 0 || savedLayer.Level >= GameData.map.Length) continue;

            Layer layer = GameData.map[savedLayer.Level];
            layer.isGateOpen = savedLayer.IsGateOpen;
            layer.hasContentGenerated = savedLayer.HasContentGenerated;
            layer.gateIngredients = savedLayer.GateIngredients ?? new List<Ingredient>();
            layer.currentResources = savedLayer.CurrentResources ?? new List<string>();

            ApplyTileData(layer, savedLayer.Tiles);
        }
    }

    private static void ApplyTileData(Layer layer, List<TileSaveData> savedTiles)
    {
        if (savedTiles == null) return;

        foreach (TileSaveData savedTile in savedTiles)
        {
            if (savedTile.X < 0 || savedTile.X >= GameData.layerSize) continue;
            if (savedTile.Y < 0 || savedTile.Y >= GameData.layerSize) continue;

            Tile tile = layer.tiles[savedTile.X, savedTile.Y];
            tile.collapsedMesh = savedTile.CollapsedMesh;
            tile.containsLight = savedTile.ContainsLight;
            tile.containsDecoration = savedTile.ContainsDecoration;
            tile.containsResource = savedTile.ContainsResource;
            tile.wasVisited = savedTile.WasVisited;
            tile.resource = savedTile.Resource == null ? null : GameResource.FromSaveData(savedTile.Resource);
            tile.ContentNode.Visible = savedTile.WasVisited || tile.collapsedMesh == "gate";
        }
    }
}