using NUnit.Framework;
using System;
using System.Collections.Generic;
using UnityEngine;
using System.IO;
using System.Security.Cryptography;
using System.Text;

public class DataStorageManager : MonoBehaviour
{

    public static DataStorageManager Instance;
    public LeaderboardData leaderboardData;


    //yes this is hardcoded but u should use a secure key management system
    //though I wont cover here that because if u decompile the software, search in the code and create a
    //script to decrypt the json just to modify the scores to cheat in this stupid game, my man, u have problems bigger than that ngl

    private byte[] key = Encoding.UTF8.GetBytes("1234567890123456");
    private byte[] iv = Encoding.UTF8.GetBytes("6543210987654321");


    void Awake()
    {
        if (Instance == null) Instance = this;
        else Destroy(gameObject);

        
    }

    public void SaveScores(List<int> scores)
    {
        leaderboardData = new LeaderboardData(scores);
        string json = JsonUtility.ToJson(leaderboardData);

        string hash = ComputeHash(json);

        SaveWrapper wrapper = new SaveWrapper
        {
            json = json,
            hash = hash
        };

        string wrapperJson = JsonUtility.ToJson(wrapper);

        string encrypted = Encrypt(wrapperJson);

        File.WriteAllText(Path.Combine(Application.persistentDataPath, "save.dat"), encrypted);

        Debug.Log("Secure save written");
    }

    public List<int> Load()
    {
        if (!File.Exists(Path.Combine(Application.persistentDataPath, "save.dat")))
            return new List<int>();

        string encrypted = File.ReadAllText(Path.Combine(Application.persistentDataPath, "save.dat"));
        string decrypted = Decrypt(encrypted);

        SaveWrapper wrapper = JsonUtility.FromJson<SaveWrapper>(decrypted);

        string expectedHash = ComputeHash(wrapper.json);

        if (expectedHash != wrapper.hash)
        {
            Debug.LogWarning("Save file tampered!");
            return new List<int>();
        }

        LeaderboardData data = JsonUtility.FromJson<LeaderboardData>(wrapper.json);

        Debug.Log("Secure save loaded successfully");

        return data.topScores;
    }



    private string Encrypt(string plainText)
    {
        using (Aes aes = Aes.Create())
        {
            aes.Key = key;
            aes.IV = iv;

            ICryptoTransform encryptor = aes.CreateEncryptor();

            byte[] inputBytes = Encoding.UTF8.GetBytes(plainText);
            byte[] encrypted = encryptor.TransformFinalBlock(inputBytes, 0, inputBytes.Length);

            return System.Convert.ToBase64String(encrypted);
        }
    }

    private string Decrypt(string cipherText)
    {
        using (Aes aes = Aes.Create())
        {
            aes.Key = key;
            aes.IV = iv;

            ICryptoTransform decryptor = aes.CreateDecryptor();

            byte[] inputBytes = Convert.FromBase64String(cipherText);

            byte[] decrypted = decryptor.TransformFinalBlock(
                inputBytes,
                0,
                inputBytes.Length
            );

            return Encoding.UTF8.GetString(decrypted);
        }
    }


    private string ComputeHash(string input)
    {
        using (SHA256 sha = SHA256.Create())
        {
            byte[] bytes = sha.ComputeHash(Encoding.UTF8.GetBytes(input));
            return System.Convert.ToBase64String(bytes);
        }
    }

}




public class SaveWrapper
{
    public string json;
    public string hash;
}


[Serializable]
public class LeaderboardData
{
    public List<int> topScores = new List<int>();

    public LeaderboardData(List<int> newScores)
    {
        topScores = newScores;
    }
}