PairingHostedService.cs

using Discord.WebSocket;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using RustPlusBot.Features.Pairing.Supervisor;

namespace RustPlusBot.Features.Pairing.Hosting;

/// <summary>Drives the supervisor from the host lifecycle: start listeners on Ready, stop them on shutdown.</summary>
/// <param name="client">The socket client (for the Ready event).</param>
/// <param name="supervisor">The pairing supervisor.</param>
/// <param name="logger">The logger.</param>
internal sealed partial class PairingHostedService(
    DiscordSocketClient client,
    IPairingSupervisor supervisor,
    ILogger<PairingHostedService> logger) : IHostedService
{
    private bool _started;

    /// <inheritdoc />
    public Task StartAsync(CancellationToken cancellationToken)
    {
        client.Ready += OnReadyAsync;
        return Task.CompletedTask;
    }

    /// <inheritdoc />
    public async Task StopAsync(CancellationToken cancellationToken)
    {
        client.Ready -= OnReadyAsync;
        await supervisor.StopAllAsync().ConfigureAwait(false);
    }

    private async Task OnReadyAsync()
    {
        // Ready fires on every (re)connect; only start listeners once per process.
        if (_started)
        {
            return;
        }

        _started = true;
        try
        {
            await supervisor.StartAllActiveAsync().ConfigureAwait(false);
        }
#pragma warning disable CA1031 // Broad catch is intentional: a failed startup must not crash the host.
        catch (Exception ex)
        {
            LogStartupFailed(ex);
        }
#pragma warning restore CA1031
    }

    [LoggerMessage(Level = LogLevel.Error, Message = "Failed to start FCM pairing listeners.")]
    private partial void LogStartupFailed(Exception exception);
}