using InboxIntel.Infrastructure.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace InboxIntel.Infrastructure.Retention;

/// <summary>
/// Daily driver for <see cref="RetentionService"/> (AUDIT H-3). Exits immediately when both
/// retention knobs are 0 (the default) so existing deployments see no behaviour change.
/// </summary>
public class RetentionWorker : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly DataRetentionOptions _options;
    private readonly ILogger<RetentionWorker> _logger;

    public RetentionWorker(IServiceScopeFactory scopeFactory, IOptions<DataRetentionOptions> options, ILogger<RetentionWorker> logger)
    {
        _scopeFactory = scopeFactory;
        _options = options.Value;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        if (_options.PurgeTrashedAfterDays <= 0 && _options.PurgeAllAfterDays <= 0)
        {
            _logger.LogDebug("RetentionWorker idle: retention is disabled (all knobs 0).");
            return;
        }

        _logger.LogInformation("RetentionWorker started; trashed>{Trashed}d, all>{All}d",
            _options.PurgeTrashedAfterDays, _options.PurgeAllAfterDays);

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                using var scope = _scopeFactory.CreateScope();
                var service = scope.ServiceProvider.GetRequiredService<RetentionService>();
                await service.PurgeAsync(stoppingToken);
            }
            catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested) { break; }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Retention purge failed; will retry next cycle.");
            }
            await Task.Delay(TimeSpan.FromHours(24), stoppingToken);
        }
    }
}