DD.WellWorkover.Cloud/AsbCloudWebApi/SignalR/ReportsHub.cs

using AsbCloudApp.Data;
using AsbCloudInfrastructure.Background;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.SignalR;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace AsbCloudWebApi.SignalR
{
    // SignalR manual:
    // https://docs.microsoft.com/ru-ru/aspnet/core/signalr/introduction?view=aspnetcore-5.0

    [Authorize]
    public class ReportsHub : BaseHub<IReportHubClient>
    {
        private readonly BackgroundWorker backgroundWorker;

        public ReportsHub(BackgroundWorker backgroundWorker)
        {
            this.backgroundWorker = backgroundWorker;
        }

        public override async Task AddToGroup(string groupName)
        {
            await base.AddToGroup(groupName);

            var workId = groupName.Replace("Report_", "");
            var work = backgroundWorker.WorkStore.RunOnceQueue.FirstOrDefault(work => work.Id == workId);

            var progress = new ReportProgressDto()
            {
                Operation = "Ожидает начала в очереди.",
                Progress = 0f,
            };

            var state = work?.CurrentState;          
            if (state is not null)
            {
                progress.Operation = state.State;
                progress.Progress = (float)state.Progress;
            }

            await Clients.Group(groupName).SendAsync(
                nameof(IReportHubClient.GetReportProgress),
                progress,
                CancellationToken.None
            );

        }
    }
}