presence/Presence.Desktop/ViewModels/StartViewModel.cs

using Demo.Domain.UseCase;
using Microsoft.Extensions.DependencyInjection;
using ReactiveUI;
using System;
using System.Reactive;

namespace Presence.Desktop.ViewModels
{
    public class StartViewModel : ViewModelBase, IRoutableViewModel
    {
        public IScreen HostScreen { get; }
        public string? UrlPathSegment => "start";

        public ReactiveCommand<Unit, Unit> OpenGroupCommand { get; }
        public ReactiveCommand<Unit, Unit> OpenPresenceCommand { get; }
        public ReactiveCommand<Unit, Unit> GoBackCommand { get; }

        public StartViewModel(IScreen hostScreen)
        {
            HostScreen = hostScreen;

            OpenGroupCommand = ReactiveCommand.Create(() =>
            {
                HostScreen.Router.Navigate.Execute(new GroupViewModel(
                    App.ServiceProvider.GetRequiredService<IGroupUseCase>(),
                    App.ServiceProvider.GetRequiredService<IUserUseCase>(),
                    HostScreen
                ));
            });

            OpenPresenceCommand = ReactiveCommand.Create(() =>
            {
                HostScreen.Router.Navigate.Execute(new PresenceViewModel(HostScreen));
            });

            GoBackCommand = ReactiveCommand.Create(() =>
            {
                HostScreen.Router.Navigate.Execute(new StartViewModel(HostScreen));
            });
        }
    }
}