using System.Collections.Generic;
using System.IO;
using UnityEngine;
using game;

public partial class GameData /*: IServerInstallation*/
{
    public static readonly string StateFileExt = ".dat";

    //NOTE: they are property accessors, not "static readonly" fields
    //because you can't access persistentDataPath in static constructor
    public static string StateFileDir => Application.persistentDataPath;
    public static string DefaultDataFile => $"{StateFileDir}/{Settings.DATA_FILE}";

    public string DataFile { get; private set; }
    public string AesSecret { get; private set; }
    public string ClientVersion { get; private set; }
    public bool SaveInProgress { get; private set; }
    public string ExtID => _lastSave.local.extId;
    public uint PlayerID => _lastSave.local.player.id;

    private int _forbidSaves = 0;
    private DataSave _lastSave = new DataSave();
    private readonly List<IPersistent> _persistentStructures = new List<IPersistent>();

    public GameData(string clientVersion)
        : this(DefaultDataFile, clientVersion)
    {
    }

    public GameData(string dataFile, string clientVersion)
    {
        DataFile = dataFile;
        ClientVersion = clientVersion;
        AesSecret = SystemInfo.deviceUniqueIdentifier.Reverse();

        _lastSave.reset();
    }

    public SaveDiagnostics CollectSaveDiagnostics(PersistError persist_error)
    {
        var d = new SaveDiagnostics();
        d.LastSaveAppVersion = PlayerPrefs.GetString("last_save_app_version", "");
        d.LastSaveFile = PlayerPrefs.GetString("last_save_file", "");
        d.LastSaveDeviceID = PlayerPrefs.GetString("last_save_device_id", "");
        d.SaveFile = DataFile;
        d.SaveDir = Path.GetDirectoryName(DataFile);
        d.IsDirWritable = IsDirectoryWritable(d.SaveDir);
        d.PersistError = persist_error;
        return d;
    }

    public void RememberSuccessfulSave()
    {
        PlayerPrefs.SetString("last_save_ext_id", ExtID);
        PlayerPrefs.SetString("last_save_file", DataFile);
        PlayerPrefs.SetString("last_save_device_id", SystemInfo.deviceUniqueIdentifier);
        PlayerPrefs.SetString("last_save_app_version", Settings.VERSION);
    }

    public string GetLastSuccessfulSaveExtId()
    {
        return PlayerPrefs.GetString("last_save_ext_id", "");
    }

    void ResetLastSuccessfulSave()
    {
        PlayerPrefs.DeleteKey("last_save_ext_id");
        PlayerPrefs.DeleteKey("last_save_file");
        PlayerPrefs.DeleteKey("last_save_device_id");
        PlayerPrefs.DeleteKey("last_save_app_version");
    }

    public static bool IsDirectoryWritable(string dir)
    {
        try
        {
            using (var fs = File.Create(
                Path.Combine(dir, Path.GetRandomFileName()),
                1,
                FileOptions.DeleteOnClose)
            ){}

            return true;
        }
        catch
        {
            return false;
        }
    }

    public bool CanSave()
    {
        return _forbidSaves == 0 && _persistentStructures.Count > 0;
    }

    public void ForbidSaves()
    {
        _forbidSaves++;
        Log.Debug($"ForbidSaves, counter: {_forbidSaves}");
    }

    public void AllowSaves()
    {
        _forbidSaves--;
        
        if (_forbidSaves < 0)
            _forbidSaves = 0;

        Log.Debug($"AllowSaves, counter: {_forbidSaves}");
    }

    public void ResetForbidSaves()
    {
        _forbidSaves = 0;
        Log.Debug("All saves allowed");
    }

    public bool IsAttachedToServer()
    {
        return string.IsNullOrEmpty(ExtID) == false;
    }

    private bool IsRemoteStateSynced()
    {
        return string.IsNullOrEmpty(_lastSave.remote.extId) == false;
    }

    //TODO: not needed at the moment
    //public void AttachToServer(uint player_id, string ext_id, uint reg_time)
    //{
    //  Log.Warn("Attached to server as " + player_id + ", ext.id " + ext_id);

    //  last_save.local.ext_id = ext_id;
    //  last_save.local.player.id = player_id;
    //  last_save.local.player.reg_time = reg_time;

    //  last_save.remote.reset();
    //}

    private static DataGame CreateInitial()
    {
        return new DataGame();
    }

    public void RegisterPersistentStructure(IPersistent persistent)
    {
        Error.Assert(persistent != null);
        _persistentStructures.Add(persistent);
    }

    public void RegisterPersistentStructures(params IPersistent[] structures)
    {
        for (int i = 0; i < structures.Length; i++)
            RegisterPersistentStructure(structures[i]);
    }

    public void UnregisterPersistentStructures()
    {
        _persistentStructures.Clear();
    }

    public void Load()
    {
        var save = new DataSave();

        if (Persister.LoadFromFile(ref save, DataFile, AesSecret) != 0)
            return;

        Load(save);
    }

    private void Load(DataSave save)
    {
        if (!ValidateSave(save))
        {
            Log.Warn("GameData.Load: State validation error, resetting remote state");
            save.remote.reset();
        }

        _lastSave = save;

        Log.Debug("GameData.Load: Loaded save with ext.id " + ExtID);

        for (int i = 0; i < _persistentStructures.Count; i++)
            _persistentStructures[i].Load(_lastSave.local);
    }

    public LoadOrCreateResult TryLoadOrCreateNew()
    {
        var save = new DataSave();
        var err = Persister.LoadFromFile(ref save, DataFile, AesSecret);

        var res = new LoadOrCreateResult();
        res.PersistError = err;
        res.Status = LoadOrCreateStatus.LOAD;

        if (err != 0)
        {
            save.local = CreateInitial();
            save.remote = (DataGame) save.local.clone();
            res.Status = LoadOrCreateStatus.NEW;
        }

        Load(save);
        return res;
    }

    private void FillState(ref DataGame new_state)
    {
        new_state.reset();

        for (int i = 0; i < _persistentStructures.Count; i++)
            _persistentStructures[i].Save(new_state);

        //NOTE: need to preserve existing data
        new_state.extId = _lastSave.local.extId;
        new_state.player.id = _lastSave.local.player.id;
    }

    public PersistError SaveLocal()
    {
        PersistError err = new PersistError();

        if (!CanSave())
            return err;

        var new_state = new DataGame();
        FillState(ref new_state);

        //NOTE: not checking delta diff here on purpose,
        //      this is a save which must be done
        //      for sure

        var new_save = _lastSave;
        new_save.local = new_state;

        err = Persister.SaveToFile(new_save, DataFile, AesSecret);
        
        if (err != 0)
            _lastSave = new_save;

        return err;
    }

    public void ResetProgress(bool preserve_identity)
    {
        //preserving essential stuff if it's needed by keep_ext_id flag
        var ext_id = _lastSave.local.extId;
        var player_id = _lastSave.local.player.id;

        _lastSave.local = CreateInitial();

        if (preserve_identity)
        {
            //..and restoring it back if necessary
            _lastSave.local.extId = ext_id;
            _lastSave.local.player.id = player_id;
        }
        else
        {
            //disabling emergency restore
            ResetLastSuccessfulSave();
        }

        _lastSave.remote.reset();

        var err = Persister.SaveToFile(_lastSave, DataFile, AesSecret);
        if (err == 0)
            Log.Warn("Progress was reset");

        //we unregister them so that on the next save no data will be
        //collected
        UnregisterPersistentStructures();
    }

    //TODO: not needed at the moment
    //async public UniTask<PersistError> Restore(bool keep_my_data, DataGame restored)
    //{
    //  if(save_in_progress)
    //    await UniTask.WaitUntil(() => !save_in_progress);

    //  if(!keep_my_data)
    //  {
    //    Error.Assert(restored.player.id > 0, "Bad id");
    //    Error.Assert(!string.IsNullOrEmpty(restored.ext_id), "Bad ext.id");

    //    Log.Warn("Restoring from player id " + restored.player.id + ", ext.id " + restored.ext_id);

    //    last_save.local.copyFrom(restored);
    //    last_save.remote.copyFrom(restored);
    //  }
    //  else
    //  {
    //    Log.Warn("Keeping my data as player id " + PLAYER_ID);
    //    //we need to make the full remote save next time
    //    last_save.remote.reset();
    //  }

    //  return Persister.SaveToFile(last_save, DATA_FILE, AES_SEKRET);
    //}

    public static bool ValidateSave(DataSave save)
    {
        return true;
    }

#if UNITY_EDITOR
    public static void ClearAll()
    {
        Error.Assert(!UnityEditor.EditorApplication.isPlaying, "Removed state files might be rewritten by running game");
        DeleteAllExceptBackupSaves();
        PlayerPrefs.SetString("last_save_file", "");
        PlayerPrefs.SetString("last_save_ext_id", "");
    }

    static void DeleteAllExceptBackupSaves()
    {
        string[] files = Directory.GetFiles(StateFileDir);
        foreach (string path in files)
        {
            File.Delete(path);
        }

        string[] dirs = Directory.GetDirectories(StateFileDir);
        foreach (string path in dirs)
        {
            if (path.EndsWith("/backup"))
                continue;

            Directory.Delete(path, recursive: true);
        }

        Directory.Delete(Application.temporaryCachePath, recursive: true);
    }

    public PersistError DevWriteToFile(string path, DataGame state)
    {
        var save = new DataSave();
        save.reset();
        save.local.copyFrom(state);
        save.remote.copyFrom(state);
        return Persister.SaveToFile(save, path, AesSecret);
    }

    public DataGame DevGetState()
    {
        return _lastSave.local;
    }
#endif
}