using Microsoft.AspNetCore.SignalR;
using PlotLine.Hubs;

namespace PlotLine.Services;

public sealed class WordCompanionPresenceMonitor(
    IWordCompanionPresenceService presence,
    IHubContext<WordCompanionFollowHub> hub) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        using var timer = new PeriodicTimer(TimeSpan.FromSeconds(10));
        try
        {
            while (await timer.WaitForNextTickAsync(stoppingToken))
            {
                var offlineStatuses = await presence.MarkStaleOfflineAsync();
                foreach (var status in offlineStatuses)
                {
                    await hub.Clients
                        .Group(PresenceGroup(status.UserID))
                        .SendAsync("WordCompanionPresenceChanged", status, stoppingToken);
                }
            }
        }
        catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
        {
        }
    }

    private static string PresenceGroup(int userId) => $"word-companion-presence:{userId}";
}