using System.Collections.Immutable;
using System.Runtime.CompilerServices;
using System.Text.Json.Nodes;

namespace StellaOps.Graph.Indexer.Incremental;

/// <summary>
/// No-op change/backfill source used when no external change feed is configured.
/// </summary>
public sealed class NoOpGraphChangeEventSource : IGraphChangeEventSource, IGraphBackfillSource
{
    public IAsyncEnumerable<GraphChangeEvent> ReadAsync(CancellationToken cancellationToken) =>
        ReadInternalAsync(cancellationToken);

    public IAsyncEnumerable<GraphChangeEvent> ReadBackfillAsync(CancellationToken cancellationToken) =>
        ReadInternalAsync(cancellationToken);

    private static async IAsyncEnumerable<GraphChangeEvent> ReadInternalAsync([EnumeratorCancellation] CancellationToken cancellationToken)
    {
        await Task.CompletedTask.ConfigureAwait(false);
        yield break;
    }
}