using MailSharp.MailClient.Models;
using Microsoft.Extensions.Options;

namespace MailSharp.MailClient.Services.Logging;

// Keeps App_Data/logs.db from growing unbounded - prunes on startup and then periodically, rather
// than capping the collection size, so retention is time-based (predictable for someone reading
// the Maintenance log viewer) instead of silently dropping whichever entries happen to be oldest
// once some row-count limit is hit.
public class LogPruningService(ILogStore logStore, IOptions<MailSettings> mailSettings, ILogger<LogPruningService> logger) : BackgroundService
{
	private static readonly TimeSpan PruneInterval = TimeSpan.FromHours(6);

	protected override async Task ExecuteAsync(CancellationToken stoppingToken)
	{
		Prune();

		using var timer = new PeriodicTimer(PruneInterval);
		while (await timer.WaitForNextTickAsync(stoppingToken))
		{
			Prune();
		}
	}

	private void Prune()
	{
		try
		{
			var retentionDays = Math.Max(1, mailSettings.Value.LogRetentionDays);
			logStore.PruneOlderThan(DateTime.UtcNow.AddDays(-retentionDays));
		}
		catch (Exception ex)
		{
			logger.LogWarning(ex, "Log pruning failed");
		}
	}
}