extract file from multipart-form-data

upload.scala

def storeUploadedFile(data: Source[ByteString, Any]): \/[Seq[Throwable], Future[DefaultPath]] = {
    val tmpUpload = Path.createTempFile(prefix = "uploaded", dir = settings.TempDir, deleteOnExit = true)

    try {
      val os = new FileOutputStream(tmpUpload.jfile)
      val sink = OutputStreamSink(() => os)
      val f = data.runWith(sink).map(_ => tmpUpload)
      f.onComplete { _ =>
        info(s"Stored temporary uploaded PDF ${tmpUpload.path}")
        os.close
      }
      f.right
    } catch {
      case e: IOException =>
        Seq(e).left
    }
    //TODO(AR) delete the temp file after we process it and have a new file
}


entity(as[Multipart.FormData]).flatMap { (formdata: Multipart.FormData) =>
  val extractedParts = formdata.parts.mapAsync(Runtime.getRuntime.availableProcessors) { part =>
      val reqParamValue = part.filename match {
        case Some(filename) =>
          storeUploadedFile(part.entity.dataBytes) match {
            case \/-(tmpPath) =>
              tmpPath.map(ReqParamFileValue(filename, part.entity.contentType, _))
            case -\/(throwables) =>
              //TODO(AR) log all errors
              throw throwables.head
          }
        case None =>
          part.entity.dataBytes
            .runFold("")((a,b) => a + b.decodeString(StandardCharsets.UTF_8.name))
            .map(ReqParamStringValue(_))
      }
      reqParamValue.map(ReqParam(part.name, _))
  }.runFold(Map.empty[String, ReqParam])((m, b) => m + (b.name -> b))

  val futureMaybeStampPdfRequest: Future[\/[Rejection, StampPdfRequest]] = extractedParts.map(parts =>
    for {
      pdfStamp <- extractPdfStamp(parts)
      pdf <- extractFile(parts, "pdf")
      coverPage <- extractCoverPageOpt(parts)
    } yield StampPdfRequest(pdfStamp, coverPage, pdf)
  )

  Await.result(
    futureMaybeStampPdfRequest.map {
      case -\/(rejection) =>
        reject(rejection)
      case \/-(stampPdfRequest) =>
        provide(stampPdfRequest)
    },
    5 minutes //TODO(AR) make configurable
  )
}