namespace ErsatzTV.Core.Metadata;

// #484: the narrow seam that carries "how many items did the server return that we silently dropped
// because their projection threw?" out of a media-server API client and back to the scanner that owns
// the reconciliation sweep.
//
// Lifetime is deliberately PER ENUMERATION: the scanner that is about to run a sweep creates one
// instance, hands it to the single library-items call whose result it will diff, and reads Count only
// after that enumeration has completed. The API clients are long-lived singletons and scans for
// different libraries run concurrently, so the counter must never be a field on a client or any
// ambient/static state — that would leak one library's failures into another library's sweep decision.
// Increments are interlocked anyway so a paginator that ever fans out stays correct.
public sealed class MediaServerProjectionFailureCounter
{
    private int _count;

    /// <summary>
    /// Number of items the server returned whose projection threw and was swallowed.
    /// </summary>
    public int Count => Volatile.Read(ref _count);

    public void RecordFailure() => Interlocked.Increment(ref _count);
}