DemoService/MainWindow.axaml.cs

using Avalonia.Controls;
using Avalonia.Interactivity;

namespace DemoService
{
    public partial class MainWindow : Window
    {
        private readonly string adminCode = "0000";
        public MainWindow()
        {
            InitializeComponent();
            Background = Colors.white;
            UserButton.Background = Colors.orange;
            PasswordError.Foreground = Colors.white;
            AdminButton.Background = Colors.orange;
        }
        public void UserLogIn(object sender, RoutedEventArgs args)
        {
            ServiceWindow serviceWindow = new(false);
            serviceWindow.Show();
            Close();
        }
        public void AdminLogIn(object sender, RoutedEventArgs args)
        {
            if (PasswordCheck(Password.Text))
            {
                ServiceWindow serviceWindow = new(true);
                serviceWindow.Show();
                Close();
            }
            else
            {
                PasswordError.Foreground = Colors.red;
            }    
        }
        public bool PasswordCheck(string? password)
        {
            if (password == adminCode)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }
}