gamenight/FrontendAvalonia/FrontendAvalonia/App.axaml.cs

using System;
using Avalonia;
using Avalonia.Controls.ApplicationLifetimes;
using Avalonia.Markup.Xaml;
using FrontendAvalonia.Extensions;
using FrontendAvalonia.Models;
using FrontendAvalonia.Services.GamenightApi;
using FrontendAvalonia.ViewModels;
using FrontendAvalonia.Views;
using ReactiveUI;
using Refit;
using Splat;

namespace FrontendAvalonia;

public partial class App : Application
{
    public override void Initialize()
    {
        AvaloniaXamlLoader.Load(this);
    }

    public override void OnFrameworkInitializationCompleted()
    {
        var mutable = Locator.CurrentMutable;
        var locator = Locator.Current ?? throw new InvalidOperationException("Locator should not be null here.");
        mutable.RegisterLazySingleton(() => new GamenightModel());

        mutable.RegisterLazySingleton<IScreen>(() => new MainScreenViewModel());
        mutable.RegisterLazySingleton(() => RestService.For<IGamenight>("http://localhost:8080"));

        mutable.Register(() => new AddGamenightViewModel(
            locator.GetRequiredService<IGamenight>(), 
            locator.GetRequiredService<GamenightModel>()));
        mutable.Register(() => new LoginViewModel(
            locator.GetRequiredService<IScreen>(), 
            locator.GetRequiredService<IGamenight>(), 
            locator.GetRequiredService<GamenightModel>()));
        mutable.Register(() => new GamenightsViewModel(
            locator.GetRequiredService<IScreen>(),
            locator.GetRequiredService<IGamenight>(),
            locator.GetRequiredService<GamenightModel>(),
            locator.GetRequiredService<LoginViewModel>()));
        mutable.Register(() => new MainViewModel(
            locator.GetRequiredService<IScreen>(), 
            locator.GetRequiredService<GamenightModel>(), 
            locator.GetRequiredService<IGamenight>(), 
            locator.GetRequiredService<LoginViewModel>(),
            locator.GetRequiredService<GamenightsViewModel>()));


        if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
        {
            desktop.MainWindow = new MainWindow
            {
                DataContext = Locator.Current.GetService<MainViewModel>()
            };
        }
        else if (ApplicationLifetime is ISingleViewApplicationLifetime singleViewPlatform)
        {
            singleViewPlatform.MainView = new MainView
            {
                DataContext = Locator.Current.GetService<MainViewModel>()
            };
        }

        Locator.Current.GetService<IScreen>()?.Router.Navigate.Execute(Locator.Current.GetService<GamenightsViewModel>() ?? throw new InvalidOperationException("Could not find initial viewmodel to navigate to"));

        base.OnFrameworkInitializationCompleted();
    }
}