Demo/Program.cs

using Demo.Data.RemoteData.RemoteDataBase;
using Demo.Data.Repository;
using Demo.Domain.UseCase;
using Demo.UI;
using Microsoft.Extensions.DependencyInjection;

IServiceCollection services = new ServiceCollection();

	services

    .AddDbContext<RemoteDatabaseContext>()
    .AddSingleton<IGroupRepository, SQLGroupRepositoryImpl>()
    .AddSingleton<IUserRepository, SQLUserRepositoryImpl>()
    .AddSingleton<IPresenceRepository, SQLPresenceRepositoryImpl>()
    .AddSingleton<IGroupUseCase, GroupUseCase>()
    .AddSingleton<IUserUseCase, UserUseCase>()
    .AddSingleton<IPresenceUseCase, PresenceUseCase>()
    .AddSingleton<UserConsoleUI>()
    .AddSingleton<MainMenuUI>();

 var serviceProvider = services.BuildServiceProvider();

 MainMenuUI? mainMenuUI = serviceProvider.GetService<MainMenuUI>();