register-referentie/services/event-subscriber/EventSubscriber.Application/Ports.cs

namespace EventSubscriber.Application;

/// <summary>
/// The durable log of notifications the subscriber has accepted. It is both the idempotency
/// guard (a replayed notification is recognised and dropped) and the rebuild source: the
/// projection is a derived artefact (PRD §8.4) regenerated by replaying this log, so a rebuild
/// needs no access to Objecten or ZGW (CLAUDE.md §8.1). Implemented in Infrastructure over Postgres.
/// </summary>
public interface INotificationLog
{
    /// <summary>
    /// Record a notification. Returns <c>true</c> if it was newly recorded, <c>false</c> if an
    /// entry with the same key already existed (a duplicate delivery). Must be atomic so that
    /// concurrent duplicate deliveries cannot both observe <c>true</c>.
    /// </summary>
    Task<bool> TryRecordAsync(RecordedNotification notification, CancellationToken ct = default);

    /// <summary>Every accepted notification, for rebuilding the projection.</summary>
    Task<IReadOnlyList<RecordedNotification>> AllAsync(CancellationToken ct = default);
}

/// <summary>
/// An accepted notification, retaining exactly the projection row it produced — so a rebuild
/// reproduces the row by replaying the log, without re-reading Objecten (S-19b-2, ADR-0030).
/// </summary>
public sealed record RecordedNotification(string Key, string RegisterId, string Status, string? Reference);

/// <summary>
/// Port to the Anti-Corruption Layer. An Objecten notification carries only the object URL, so the
/// subscriber reads the register record back through the ACL — the only code that may talk to
/// Objecten (§8.1, ADR-0028) — rather than reading Objecten itself.
/// </summary>
public interface IAclClient
{
    /// <summary>The register record the object at <paramref name="objectUrl"/> holds, or
    /// <c>null</c> if it holds none — the object may be gone by the time a redelivered
    /// notification is handled, which is not an error (§8.6).</summary>
    Task<RegisterRecord?> GetRegisterRecordAsync(Uri objectUrl, CancellationToken ct = default);
}

/// <summary>The public-safe register record as the ACL returns it — the RegisterRecord objecttype's
/// schema (ADR-0027). No bsn, no name: the register is world-readable.</summary>
public sealed record RegisterRecord(string Id, string Status, string? Reference);

/// <summary>The read projection store. Owned by the projection bounded context (ADR-0008); the
/// subscriber writes to it and the projection-api reads it.</summary>
public interface IProjectionStore
{
    /// <summary>Insert or update the row for <see cref="RegisterEntry.Id"/>. Idempotent on the id.</summary>
    Task UpsertAsync(RegisterEntry entry, CancellationToken ct = default);

    /// <summary>Remove every row — the first step of a rebuild.</summary>
    Task ClearAsync(CancellationToken ct = default);

    /// <summary>Every projection row (used by tests and the rebuild verification).</summary>
    Task<IReadOnlyList<RegisterEntry>> AllAsync(CancellationToken ct = default);
}