private void LoginClick(object sender, RoutedEventArgs e) { LoginCredentials loginCredentials = new LoginCredentials(emailTextBox.Text, passwordTextBox.Password); string cookie = loginCredentials.Login(loginCredentials); if (cookie != null) { LoggedUser loggedUser = new LoggedUser(loginCredentials, Role.Doctor, cookie); HospitalMainWindow window = HospitalMainWindow.GetInstance(); this.Close(); window.ShowDialog(); } else { MessageBox.Show("You have enetered wrong email or password!"); } }