using System;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace ChapterX.Domain.Shared
{
    public class PasswordHasher
    {
        public static string HashPassword(string password)
        {
            byte[] salt;
            new RNGCryptoServiceProvider().GetBytes(salt = new byte[16]);

            var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 10000, HashAlgorithmName.SHA256);
            byte[] hash = pbkdf2.GetBytes(20);

            byte[] hashBytes = new byte[36];
            Array.Copy(salt, 0, hashBytes, 0, 16);
            Array.Copy(hash, 0, hashBytes, 16, 20);

            return Convert.ToBase64String(hashBytes);
        }

        public static bool VerifyPassword(string password, string storedHash)
        {
            byte[] hashBytes = Convert.FromBase64String(storedHash);
            byte[] salt = new byte[16];
            Array.Copy(hashBytes, 0, salt, 0, 16);

            var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 10000, HashAlgorithmName.SHA256);
            byte[] hash = pbkdf2.GetBytes(20);

            for (int i = 0; i < 20; i++)
            {
                if (hashBytes[i + 16] != hash[i])
                {
                    return false;
                }
            }
            return true;
        }
    }
}