using Big.Domain;

namespace Big.Application;

/// <summary>A behandelaar's decision to approve a registration, in domain language.</summary>
public sealed record ApproveRegistrationCommand(RegistrationId RegistrationId);

/// <summary>
/// The approve use case (S-09b): set the registration's zaak to its final status via the ACL (§8.1),
/// then advance the aggregate to INGESCHREVEN. Idempotent — a redelivered or repeated approval of an
/// already-approved registration is a no-op, so the ACL is not asked to set the status twice. The
/// zaak status is the projection's source of truth (it flows back over NRC); the aggregate transition
/// keeps the domain's own view consistent.
/// </summary>
public sealed class ApproveRegistration(IRegistrationStore store, IAclClient acl)
{
    public async Task HandleAsync(ApproveRegistrationCommand command, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(command);

        var registration = await store.GetAsync(command.RegistrationId, ct)
            ?? throw new InvalidOperationException($"No registration {command.RegistrationId} to approve.");

        // A repeated approval is a no-op: don't set the zaak status a second time.
        if (registration.Status == RegistrationStatus.Ingeschreven)
            return;

        if (registration.ZaakUrl is null)
            throw new InvalidOperationException(
                $"Registration {command.RegistrationId} has no zaak yet; it cannot be approved.");

        await acl.ApproveZaakAsync(registration.ZaakUrl, ct);
        registration.Approve();
        await store.SaveAsync(registration, ct);
    }
}