using Big.Domain;

namespace Big.Application;

/// <summary>A zorgprofessional's request to withdraw their own registration ("trek aanvraag in").
/// <paramref name="Bsn"/> is the authenticated caller (from the DigiD token, forwarded by the BFF):
/// only the registration's own bsn may withdraw it.</summary>
public sealed record WithdrawRegistrationCommand(RegistrationId RegistrationId, string Bsn);

/// <summary>The outcome of a withdrawal request.</summary>
public enum WithdrawOutcome
{
    /// <summary>The registration is now (or already was) INGETROKKEN.</summary>
    Withdrawn,

    /// <summary>No registration with that id belongs to the caller — unknown, or owned by someone
    /// else (the two are deliberately indistinguishable, so the endpoint reveals neither).</summary>
    NotFound,
}

/// <summary>
/// The withdrawal use case (S-11): a zorgprofessional pulls a still-open registration back. It
/// advances the aggregate to INGETROKKEN, persists it, then cancels the running registratie process
/// by correlating the withdrawal message to its instance (ADR-0014), so the case leaves the
/// behandelaar's werkbak. Idempotent — a repeated or redelivered withdrawal of an already-withdrawn
/// registration is a no-op (not persisted or cancelled again). Cancelling is best-effort: if the
/// registration never started a process the withdrawal still stands (the process cancel is skipped),
/// mirroring how <see cref="BeoordeelRegistratie"/> completes its task best-effort.
/// </summary>
public sealed class WithdrawRegistration(IRegistrationStore store, IWorkflowClient workflow)
{
    public async Task<WithdrawOutcome> HandleAsync(WithdrawRegistrationCommand command, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(command);

        var registration = await store.GetAsync(command.RegistrationId, ct);

        // Unknown, or not the caller's registration: report NotFound either way (don't reveal which).
        if (registration is null || registration.Bsn != command.Bsn)
            return WithdrawOutcome.NotFound;

        // A repeated withdrawal is a no-op: don't persist or cancel the already-withdrawn one again.
        if (registration.Status == RegistrationStatus.Ingetrokken)
            return WithdrawOutcome.Withdrawn;

        registration.Withdraw();
        await store.SaveAsync(registration, ct);

        // Cancel the running process (if one was started) so its Beoordelen task leaves the werkbak.
        if (registration.ProcessInstanceId is not null)
            await workflow.WithdrawProcessAsync(registration.ProcessInstanceId, ct);

        return WithdrawOutcome.Withdrawn;
    }
}