using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;

namespace Big.Infrastructure;

/// <summary>
/// The hosted polling loop of the external-task job worker (ADR-0009): on an interval it resolves a
/// scoped <see cref="OpenZaakJobProcessor"/> and asks it to drain the parked <c>OpenZaakAanmaken</c>
/// jobs. A deliberately thin shell — all acquire/process/complete logic lives in the processor, which
/// is unit-tested; this class only owns the timer, the per-tick scope, and loop resilience.
/// </summary>
public sealed class OpenZaakJobPump(
    IServiceScopeFactory scopeFactory,
    FlowableOptions options,
    ILogger<OpenZaakJobPump> logger) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                using var scope = scopeFactory.CreateScope();
                var processor = scope.ServiceProvider.GetRequiredService<OpenZaakJobProcessor>();
                await processor.PumpOnceAsync(options.MaxJobsPerPoll, stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                break;
            }
            catch (Exception ex)
            {
                // A transient fault (e.g. Flowable briefly unreachable) must not kill the loop.
                logger.LogError(ex, "OpenZaakAanmaken job poll failed; retrying after the poll interval.");
            }

            try
            {
                await Task.Delay(options.PollInterval, stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
            {
                break;
            }
        }
    }
}