LessBloatedHandler.cs

public class LessBloatedHandler
{
    private readonly DB _db;
    private readonly IEmailer _emailer;
    private readonly IEventPublisher _eventPublisher;
    private readonly ILogger _logger;

    public LessBloatedHandler(DB db, IEmailer emailer, IEventPublisher eventPublisher, ILogger logger)
    {
        _db = db;
        _emailer = emailer;
        _eventPublisher = eventPublisher;
        _logger = logger;
    }
    
    public void Handle(DispatchShipment command)
    {
        var shipment = _db.GetById(command.ShipmentId);
        if (shipment == null)
        {
            throw new InvalidOperationException("Shipment not found.");
        }

        shipment.Dispatch();

        _db.Save(shipment);
        
        _emailer.NotifyCustomer(shipment);
        
        _eventPublisher.Publish(new ShipmentDispatched(shipment.Id, shipment.DispatchedAt));
        
        _logger.Log($"Shipment {shipment.Id} dispatched.");
    }
}

public class Shipment
{
    public Guid Id { get; private set; }
    public ShipmentStatus Status { get; private set; }
    public DateTime? DispatchedAt { get; private set; }

    public void Dispatch()
    {
        if (Status != ShipmentStatus.Ready)
        {
            throw new InvalidOperationException("Shipment is not ready.");
        }

        Status = ShipmentStatus.Dispatched;
        DispatchedAt = DateTime.UtcNow;
    }
}