def callHttp = Http()

in common/src/main/scala/com/gu/multimedia/storagetier/plutocore/AssetFolderLookup.scala [30:100]
49 lines of code
9 McCabe index (conditional complexity)

  def callHttp = Http()

  private val multiSlashRemover = "^/{2,}".r

  /**
   * internal method that performs a call to pluto, handles response codes/retries and unmarshals returned JSON to a domain object.
   * If the server returns a 200 response then the content is parsed as JSON and unmarshalled into the given object
   * If the server returns a 404 response then None is returned
   * If the server returns a 403 or a 400 then a failed future is returned
   * If the server returns a 500, 502, 503 or 504 then the request is retried after (attempt*0.5) seconds up till 10 attempts
   *
   * @param req     constructed akka HttpRequest to perform
   * @param attempt attempt counter, you don't need to specify this when calling
   * @tparam T the type of domain object to unmarshal the response into. There must be an io.circe.Decoder in-scope for this kind of object.
   *           if the unmarshalling fails then a failed Future is returned
   * @return a Future containing an Option with either the unmarshalled domain object or None
   */
  protected def callToPluto[T: io.circe.Decoder](req: HttpRequest, attempt: Int = 1): Future[Option[T]] = if (attempt > 10) {
    Future.failed(new RuntimeException("Too many retries, see logs for details"))
  } else {
    logger.debug(s"PlutoCore request URL is ${req.uri.toString()}")
    val checksumBytes = MessageDigest.getInstance("SHA-384").digest("".getBytes)
    val checksumString = checksumBytes.map("%02x".format(_)).mkString
    val queryPart = req.uri.rawQueryString.map(query => "?" + query).getOrElse("")
    val messageTime = ZonedDateTime.now()

    val contentType = if (req.entity.isKnownEmpty()) {
      ""
    } else {
      req.entity.contentType.mediaType.toString()
    }

    val token = HMAC.calculateHmac(
      contentType,
      checksumString,
      method = req.method.value,
      multiSlashRemover.replaceAllIn(req.uri.path.toString(), "/") + queryPart,
      config.sharedSecret,
      messageTime
    )

    if (token.isEmpty) {
      Future.failed(new RuntimeException("could not build authorization"))
    } else {

      val auth: HttpHeader = RawHeader("Authorization", s"HMAC ${token.get}")
      val checksum = RawHeader("Digest", s"SHA-384=$checksumString")
      val date = RawHeader("Date", DateTimeFormatter.RFC_1123_DATE_TIME.format(messageTime))
      val updatedReq = req.withHeaders(scala.collection.immutable.Seq(auth, date, checksum)) //add in the authorization header

      val loggerContext = Option(MDC.getCopyOfContextMap)

      callHttp
        .singleRequest(updatedReq)
        .flatMap(response => {
          if(loggerContext.isDefined) MDC.setContextMap(loggerContext.get)
          AkkaHttpHelpers.handleResponse(response, "PlutoCore")
        })
        .flatMap({
          case Right(Some(stream))=>contentBodyToJson(consumeStream(stream.dataBytes))
          case Right(None)=>Future(None)
          case Left(RedirectRequired(newUri))=>
            logger.info(s"Redirecting to $newUri")
            callToPluto(req.withUri(newUri), attempt + 1)
          case Left(RetryRequired)=>
            Thread.sleep(500 * attempt)
            callToPluto(req, attempt + 1)
        })

    }
  }