using Big.Domain;

namespace Big.Application;

/// <summary>A zorgprofessional's request to withdraw their own registration ("trek aanvraag in").</summary>
public sealed record WithdrawRegistrationCommand(RegistrationId RegistrationId);

/// <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 delivering the withdrawal message to its open <c>Beoordelen</c> task (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/// already-withdrawn registration is a no-op (not persisted or cancelled again).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 no <c>Beoordelen</c> task is open (the process has not parked there yet, or has
/// already ended) the withdrawal still stands — mirroring <see cref="BeoordeelRegistratie"/>.
/// </summary>
public sealed class WithdrawRegistration(IRegistrationStore store, IUserTaskClient tasks)
{
    public async Task HandleAsync(WithdrawRegistrationCommand command, CancellationToken ct = default)
    {
        ArgumentNullException.ThrowIfNull(command);

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

        // A repeated withdrawal is a no-op: don't persist or cancel the already-withdrawn one again.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

        registration.Withdraw();
        await store.SaveAsync(registration, ct);
        await CancelWorkflowTaskAsync(command.RegistrationId, ct);
    }

    // Cancel the workflow: deliver the withdrawal message to the open Beoordelen task's execution so
    // the process's boundary event ends it. If none is open the withdrawal still stands.
    private async Task CancelWorkflowTaskAsync(RegistrationId registrationId, CancellationToken ct)
    {
        var open = await tasks.GetOpenBeoordelingenAsync(ct);
        var task = open.FirstOrDefault(t => t.RegistrationId == registrationId);
        if (task is not null)
            await tasks.WithdrawBeoordelingAsync(task.ExecutionId, ct);
    }
}