private void GoBack_Click(object sender, RoutedEventArgs e)
        {
            var chooseContract = new ChooseContract();

            this.Close();
            chooseContract.Show();
        }
        private async void LoginBtn_Click(object sender, RoutedEventArgs e)
        {
            if (UserName.Text == "" || UserPwd.Password == "")
            {
                MessageBox.Show("Login or/and Password are empty. Please, try again");
            }
            else
            {
                UserModel User = new UserModel();
                User.Login    = UserName.Text;
                User.Password = PasswordHasher.Encrypt(UserPwd.Password);
                using (AppDbContext context = new AppDbContext())
                {
                    var Users = await context.Users.ToListAsync();

                    foreach (var user in Users)
                    {
                        if (user.Login == User.Login)
                        {
                            if (user.Password == User.Password)
                            {
                                var chooseContract = new ChooseContract();
                                this.Close();
                                chooseContract.Show();
                            }
                        }
                    }
                    context.SaveChanges();
                }
            }
        }