5.4 Register Shopfront in one place

using Microsoft.EntityFrameworkCore;
using Shopfront.Data;
using Shopfront.Failures;
using Shopfront.Fraud;
using Shopfront.Inventory;
using Shopfront.Payments;
using Trax.Core.Decisions;
using Trax.Effect.Data.Services.DomainContext;
using Trax.Effect.Services.FailureClassifier;
 
namespace Shopfront.Extensions;
 
public static class ShopfrontServiceCollectionExtensions
{
    // Everything Shopfront's trains need, apart from Trax itself.
    public static IServiceCollection AddShopfront(
        this IServiceCollection services,
        string connectionString
    ) =>
        services
            .AddDomainDataContext<IShopfrontDbContext, ShopfrontDbContext>(options =>
                options.UseNpgsql(connectionString)
            )
            .AddScoped<Catalogue>()
            .AddSingleton<IPaymentProvider, FakePaymentProvider>()
            .AddSingleton<IFailureClassifier, ShopfrontFailureClassifier>()
            .AddSingleton<IDecider>(FraudRules.Live())
            .AddSingleton<ICandidateFraudDecider, StricterFraudRules>();
}

using Shopfront.Data;
using Shopfront.Extensions;
using Shopfront.Trains.PlaceOrder;
using Trax.Core.Exceptions;
using Trax.Effect.Data.Extensions;
using Trax.Effect.Data.Postgres.Extensions;
using Trax.Effect.Data.Services.DomainContext;
using Trax.Effect.Extensions;
using Trax.Effect.JunctionProvider.Logging.Extensions;
using Trax.Effect.Provider.Parameter.Extensions;
using Trax.Mediator.Extensions;
 
var builder = WebApplication.CreateBuilder(args);
 
var connectionString =
    builder.Configuration.GetConnectionString("Shopfront")
    ?? throw new InvalidOperationException("ConnectionStrings:Shopfront is not set.");
 
builder.Services.AddShopfront(connectionString);
 
builder.Services.AddTrax(trax =>
    trax.AddEffects(effects =>
            effects
                .UsePostgres(connectionString)
                .SaveTrainParameters()
                .AddJunctionLogger(serializeJunctionData: true)
                .AddDecisionRecording()
        )
        .AddMediator(typeof(Program).Assembly)
);
 
var app = builder.Build();
 
await app.Services.EnsureSchemaCreatedAsync<ShopfrontDbContext>();
 
app.MapPost(
    "/orders",
    async (PlaceOrderInput input, IPlaceOrderTrain train, CancellationToken cancellationToken) =>
    {
        try
        {
            return Results.Ok(await train.Run(input, cancellationToken));
        }
        catch (TrainException ex)
        {
            return Results.UnprocessableEntity(ex.Message);
        }
    }
);
 
await app.RunAsync();