using System.Security.Cryptography;
using System.Text;
using Konscious.Security.Cryptography;

namespace SimpleWiki.Services;

public static class PasswordHasher
{
    private const int Iterations = 3;
    private const int MemorySizeKb = 65536;
    private const int Parallelism = 1;
    private const int SaltLength = 16;
    private const int HashLength = 32;

    public static string HashPassword(string password)
    {
        if (string.IsNullOrWhiteSpace(password))
        {
            throw new ArgumentException("Пароль пустой.");
        }

        var salt = RandomNumberGenerator.GetBytes(SaltLength);

        using var argon2 = new Argon2id(Encoding.UTF8.GetBytes(password))
        {
            Salt = salt,
            Iterations = Iterations,
            DegreeOfParallelism = Parallelism,
            MemorySize = MemorySizeKb
        };

        var hash = argon2.GetBytes(HashLength);
        var combined = new byte[SaltLength + HashLength];

        Buffer.BlockCopy(salt, 0, combined, 0, SaltLength);
        Buffer.BlockCopy(hash, 0, combined, SaltLength, HashLength);

        return Convert.ToBase64String(combined);
    }

    public static bool VerifyPassword(string password, string hashPassword)
    {
        if (string.IsNullOrWhiteSpace(password) || string.IsNullOrWhiteSpace(hashPassword))
        {
            return false;
        }

        byte[] combined;
        try
        {
            combined = Convert.FromBase64String(hashPassword);
        }
        catch
        {
            return false;
        }

        if (combined.Length < SaltLength + HashLength)
        {
            return false;
        }

        var salt = combined.Take(SaltLength).ToArray();
        var originalHash = combined.Skip(SaltLength).Take(HashLength).ToArray();

        using var argon2 = new Argon2id(Encoding.UTF8.GetBytes(password))
        {
            Salt = salt,
            Iterations = Iterations,
            DegreeOfParallelism = Parallelism,
            MemorySize = MemorySizeKb
        };

        var newHash = argon2.GetBytes(HashLength);
        return CryptographicOperations.FixedTimeEquals(originalHash, newHash);
    }
}