Blacker.MangaScraper.ViewModel.DownloadViewModel.DownloadViewModel C# (CSharp) Метод

        public DownloadViewModel(DownloadedChapterInfo downloadInfo, ISemaphore downloadSemaphore)
        {
            if (downloadInfo == null)
                throw new ArgumentNullException("downloadInfo");

            if (downloadSemaphore == null)
                throw new ArgumentNullException("downloadSemaphore");

            if (downloadInfo.ChapterRecord == null)
                throw new ArgumentException("Chapter record is invalid.", "downloadInfo");

            if (String.IsNullOrEmpty(downloadInfo.ChapterRecord.ChapterId))
                throw new ArgumentException("Chapter record id is invalid.", "downloadInfo");

            if (downloadInfo.ChapterRecord.MangaRecord == null)
                throw new ArgumentException("Manga record is invalid.", "downloadInfo");

            if (String.IsNullOrEmpty(downloadInfo.ChapterRecord.MangaRecord.MangaId))
                throw new ArgumentException("Manga record id is invalid.", "downloadInfo");

            _downloadInfo = downloadInfo;
            _downloadSemaphore = downloadSemaphore;

            _scraper = ScraperLoader.Instance.AllScrapers.FirstOrDefault(s => s.ScraperGuid == downloadInfo.ChapterRecord.Scraper);

            if (_scraper != null)
            {
                _downloader = _scraper.GetDownloader();

                // register downloader events
                _downloader.DownloadProgress += _downloader_DownloadProgress;
                _downloader.DownloadCompleted += _downloader_DownloadCompleted;
            }

            if (!String.IsNullOrEmpty(_downloadInfo.Path))
            {
                // file was already downloaded
                State = DownloadState.Unknown;
                Completed = true;
            }
            else
            {
                // we will be downloading the file now
                State = DownloadState.Ok;
                Completed = false;
            }

            CurrentActionText = String.Empty;

            _cancelDownloadCommand = new RelayCommand(Cancel, x => !Completed);
            _removeDownloadCommand = new RelayCommand(Remove);
            _openDownloadCommand = new RelayCommand(Open, x => DownloadExists);
            _retryDownloadCommand = new RelayCommand(RetryDownload, x => _downloader != null
                                                                         && Completed
                                                                         && !DownloadExists
                                                                         && !String.IsNullOrEmpty(_downloadInfo.DownloadFolder));

            CancelText = ButtonCancelText;
        }