public async Task <bool> UserExists(string username)
 {
     using (var connection = new SqlConnection(_config.GetConnectionString("RestaurantAPI")))
     {
         if (await connection.QueryFirstOrDefaultAsync <User>(SqlQueriesFactory.GetUser(), new { Username = username }) == null)
         {
             return(false);
         }
         else
         {
             return(true);
         }
     }
 }
        public async Task <User> Login(UserForLoginDto userForLoginDto)
        {
            using (var connection = new SqlConnection(_config.GetConnectionString("RestaurantAPI")))
            {
                var user = await connection.QueryFirstOrDefaultAsync <User>(SqlQueriesFactory.GetUser(), new { Username = userForLoginDto.Username });

                if (user == null)
                {
                    return(null);
                }

                if (!VerifyPasswordHash(userForLoginDto.Password, user.PasswordHash, user.PasswordSalt))
                {
                    return(null);
                }

                return(user);
            }
        }