using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Logging;

namespace StellaOps.Provcache;

public sealed partial class WriteBehindQueue
{
    private async Task DrainAsync(CancellationToken cancellationToken)
    {
        var batch = new List<WriteBehindItem>();

        while (_channel.Reader.TryRead(out var item))
        {
            batch.Add(item);
            Interlocked.Decrement(ref _currentQueueDepth);

            if (batch.Count >= _options.WriteBehindBatchSize)
            {
                await ProcessBatchAsync(batch, cancellationToken).ConfigureAwait(false);
                batch.Clear();
            }
        }

        if (batch.Count > 0)
        {
            await ProcessBatchAsync(batch, cancellationToken).ConfigureAwait(false);
        }

        _logger.LogInformation("Write-behind queue drained");
    }
}