ANTOOZA-BACKEND/Infrastructure/Hubs/ChannelStatusBroadcaster.cs

using Application.Abstractions.Hub;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.Logging;

namespace Infrastructure.Hubs;

internal sealed class ChannelStatusBroadcaster(
    ILogger<ChannelStatusBroadcaster> logger,
    IHubContext<AppHub, IAppHubClient>? hub = null
) : IChannelStatusBroadcaster
{
    public async Task BroadcastAsync(string channelSID, bool isLive, int viewerCount, string? videoId, CancellationToken ct = default)
    {
        if (hub is null)
        {
            logger.LogWarning("[ChannelStatus] hub is null — broadcast skipped: SID={SID}, isLive={IsLive}", channelSID, isLive);
            return;
        }

        logger.LogInformation("[ChannelStatus] Broadcast → SID={SID}, isLive={IsLive}, viewers={Viewers}, videoId={VideoId}",
            channelSID, isLive, viewerCount, videoId);

        // 그룹 기반 fan-out — 사이드바/WatchView 가 AppHub.JoinChannel(channelSID) 로 가입한 클라이언트만 수신
        // 이전 Clients.All 은 30초 주기에서 모든 접속자에게 N(채널)×M(사용자) fan-out 발생
        await hub.Clients.Group($"channel:{channelSID}").ReceiveChannelStatus(new
        {
            channelSID,
            isLive,
            viewerCount,
            videoId
        });
    }
}