func resume()

in FirebaseMLModelDownloader/Sources/ModelDownloadTask.swift [88:182]
93 lines of code
5 McCabe index (conditional complexity)

  func resume() {
    // Prevent multiple concurrent downloads.
    guard downloadStatus != .downloading else {
      DeviceLogger.logEvent(level: .debug,
                            message: ModelDownloadTask.ErrorDescription.anotherDownloadInProgress,
                            messageCode: .anotherDownloadInProgressError)
      telemetryLogger?.logModelDownloadEvent(eventName: .modelDownload,
                                             status: .failed,
                                             model: CustomModel(name: remoteModelInfo.name,
                                                                size: remoteModelInfo.size,
                                                                path: "",
                                                                hash: remoteModelInfo.modelHash),
                                             downloadErrorCode: .downloadFailed)
      return
    }
    downloadStatus = .downloading
    telemetryLogger?.logModelDownloadEvent(eventName: .modelDownload,
                                           status: .downloading,
                                           model: CustomModel(name: remoteModelInfo.name,
                                                              size: remoteModelInfo.size,
                                                              path: "",
                                                              hash: remoteModelInfo.modelHash),
                                           downloadErrorCode: .noError)
    downloader.downloadFile(with: remoteModelInfo.downloadURL,
                            progressHandler: { downloadedBytes, totalBytes in
                              /// Fraction of model file downloaded.
                              let calculatedProgress = Float(downloadedBytes) / Float(totalBytes)
                              self.progressHandler?(calculatedProgress)
                            }) { result in
      self.downloadStatus = .complete
      switch result {
      case let .success(response):
        DeviceLogger.logEvent(level: .debug,
                              message: ModelDownloadTask.DebugDescription
                                .receivedServerResponse,
                              messageCode: .validHTTPResponse)
        self.handleResponse(
          response: response.urlResponse,
          tempURL: response.fileURL,
          completion: self.completion
        )
      case let .failure(error):
        var downloadError: DownloadError
        switch error {
        case let FileDownloaderError.networkError(error):
          let description = ModelDownloadTask.ErrorDescription
            .invalidHostName(error.localizedDescription)
          downloadError = .failedPrecondition
          DeviceLogger.logEvent(level: .debug,
                                message: description,
                                messageCode: .hostnameError)
          self.telemetryLogger?.logModelDownloadEvent(
            eventName: .modelDownload,
            status: .failed,
            model: CustomModel(name: self.remoteModelInfo.name,
                               size: self.remoteModelInfo.size,
                               path: "",
                               hash: self.remoteModelInfo.modelHash),
            downloadErrorCode: .noConnection
          )
        case FileDownloaderError.unexpectedResponseType:
          let description = ModelDownloadTask.ErrorDescription.invalidHTTPResponse
          downloadError = .internalError(description: description)
          DeviceLogger.logEvent(level: .debug,
                                message: description,
                                messageCode: .invalidHTTPResponse)
          self.telemetryLogger?.logModelDownloadEvent(
            eventName: .modelDownload,
            status: .failed,
            model: CustomModel(name: self.remoteModelInfo.name,
                               size: self.remoteModelInfo.size,
                               path: "",
                               hash: self.remoteModelInfo.modelHash),
            downloadErrorCode: .downloadFailed
          )
        default:
          let description = ModelDownloadTask.ErrorDescription.unknownDownloadError
          downloadError = .internalError(description: description)
          DeviceLogger.logEvent(level: .debug,
                                message: description,
                                messageCode: .modelDownloadError)
          self.telemetryLogger?.logModelDownloadEvent(
            eventName: .modelDownload,
            status: .failed,
            model: CustomModel(name: self.remoteModelInfo.name,
                               size: self.remoteModelInfo.size,
                               path: "",
                               hash: self.remoteModelInfo.modelHash),
            downloadErrorCode: .downloadFailed
          )
        }
        self.completion(.failure(downloadError))
      }
    }
  }