using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using ScadaLink.AuditLog.Payload;
using ScadaLink.Commons.Entities.Audit;
using ScadaLink.Commons.Interfaces.Repositories;
using ScadaLink.Commons.Interfaces.Services;
namespace ScadaLink.AuditLog.Central;
///
/// Central-only direct-write implementation of .
/// Wraps as a best-effort
/// audit emission path for components that originate audit events ON the central
/// node (Notification Outbox dispatch, Inbound API) — NOT for site telemetry
/// ingest (that path is the SiteAudit → AuditLogIngestActor batched flow).
///
///
///
/// Best-effort contract. Audit-write failures NEVER abort the user-facing
/// action (alog.md §13). The writer catches every exception thrown by repository
/// resolution or the insert call, logs at warning, and returns successfully.
/// Callers may still wrap the call in their own try/catch (defensive — the writer
/// is supposed to swallow).
///
///
/// Scope-per-call resolution. is a SCOPED
/// EF Core service (registered by ScadaLink.ConfigurationDatabase). The
/// writer itself is registered as a singleton (so all callers share one instance),
/// so it cannot hold a scope across calls — it opens a fresh
/// per invocation, mirroring
/// the per-message scope pattern used by AuditLogIngestActor and
/// NotificationOutboxActor.
///
///
/// Idempotency. Persistence is via InsertIfNotExistsAsync, so a
/// double-emitted event (same ) is a silent
/// no-op — the writer is safe to call from any number of dispatch paths.
///
///
public sealed class CentralAuditWriter : ICentralAuditWriter
{
private readonly IServiceProvider _services;
private readonly ILogger _logger;
private readonly IAuditPayloadFilter? _filter;
private readonly ICentralAuditWriteFailureCounter _failureCounter;
private readonly INodeIdentityProvider? _nodeIdentity;
///
/// Bundle C (M5-T6) — the central direct-write path used by the
/// NotificationOutboxActor dispatch and the Inbound API middleware also
/// needs to truncate + redact before the row hits MS SQL. The filter is
/// optional so the M4 test composition roots that don't pass one keep
/// working (they only ever write small payloads); production DI registers
/// the real filter via .
/// M6 Bundle E (T8) — adds the optional
/// so a swallowed repository
/// throw bumps the central health surface's
/// CentralAuditWriteFailures counter. Defaults to a NoOp so test
/// composition roots that don't wire the counter keep their current
/// behaviour. SourceNode-stamping (Task 12) — adds the optional
/// so central-origin rows (Notification
/// Outbox dispatch, Inbound API) carry the writing central node's
/// identifier when the caller hasn't already supplied one. Optional /
/// defaulting-to-null so M4 test composition roots that don't pass a
/// provider keep working — the caller-wins discipline means an absent
/// provider simply leaves SourceNode at whatever the caller set (often
/// null, which is the legacy behaviour).
///
public CentralAuditWriter(
IServiceProvider services,
ILogger logger,
IAuditPayloadFilter? filter = null,
ICentralAuditWriteFailureCounter? failureCounter = null,
INodeIdentityProvider? nodeIdentity = null)
{
_services = services ?? throw new ArgumentNullException(nameof(services));
_logger = logger ?? throw new ArgumentNullException(nameof(logger));
_filter = filter;
_failureCounter = failureCounter ?? new NoOpCentralAuditWriteFailureCounter();
_nodeIdentity = nodeIdentity;
}
///
/// Persists into the central AuditLog table
/// idempotently on . Stamps
/// from the central-side clock.
/// Internal failures are logged and swallowed — never thrown.
///
public async Task WriteAsync(AuditEvent evt, CancellationToken ct = default)
{
if (evt is null)
{
// Defensive — a null event is a programming bug at the caller and
// produces no meaningful audit row. Log and return.
_logger.LogWarning("CentralAuditWriter.WriteAsync received null event; ignoring.");
return;
}
try
{
// Filter BEFORE stamping IngestedAtUtc + handing to the repo. The
// filter contract is "never throws"; the null-coalesce keeps the
// M4 test composition roots (no filter passed) working unchanged.
var filtered = _filter?.Apply(evt) ?? evt;
// SourceNode-stamping (Task 12): caller-provided value wins
// (supports any future direct-write callsite that already has its
// own node id); otherwise stamp from the local
// INodeIdentityProvider, when one is wired. Production DI on
// central nodes always supplies the provider; legacy test
// composition roots that don't pass it leave SourceNode at
// whatever the caller set (often null), preserving back-compat.
if (filtered.SourceNode is null && _nodeIdentity?.NodeName is { } nodeName)
{
filtered = filtered with { SourceNode = nodeName };
}
await using var scope = _services.CreateAsyncScope();
var repo = scope.ServiceProvider.GetRequiredService();
var stamped = filtered with { IngestedAtUtc = DateTime.UtcNow };
await repo.InsertIfNotExistsAsync(stamped, ct).ConfigureAwait(false);
}
catch (Exception ex)
{
// Audit failure NEVER aborts the user-facing action — swallow and log.
// M6 Bundle E (T8): also surface the failure on the central health
// counter so a sustained audit-write outage is visible on the
// health dashboard rather than disappearing into the log file.
try
{
_failureCounter.Increment();
}
catch
{
// Counter must NEVER throw — defence in depth. Even if a
// misbehaving custom counter does, swallowing here keeps the
// best-effort contract intact.
}
// Log the input event's identifying fields. These three (EventId,
// Kind, Status) are immutable across the filter+stamp chain — the
// `with` clones above touch only SourceNode and IngestedAtUtc — so
// referencing `evt` here is intentional and equivalent to the
// stamped record for diagnostics. If you add a field here that the
// stamp chain DOES mutate (e.g., SourceNode), reference the latest
// post-stamp record name instead, not `evt`.
_logger.LogWarning(
ex,
"CentralAuditWriter failed for EventId {EventId} (Kind={Kind}, Status={Status})",
evt.EventId, evt.Kind, evt.Status);
}
}
}