io.cequence.wsclient.service.ws.PlayWSMultipartWritable.scala Maven / Gradle / Ivy

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Generic WebServices library currently only with Play WS impl./backend

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package io.cequence.wsclient.service.ws

import akka.stream.scaladsl.{FileIO, Source}
import akka.util.ByteString
import play.api.libs.ws.{BodyWritable, SourceBody}

import java.nio.file.Paths

/**
 * Adapted from `play.api.http.writeableOf_MultipartFormData` but more efficient due to the
 * fact that, rather then fully materializing, form data and files are concatenated as
 * sources/streams before sending out.
 */
object PlayWSMultipartWritable {

  /**
   * `Writeable` for `MultipartFormData`.
   */
  def writeableOf_MultipartFormData(
    charset: String
  )(
    implicit filePartToContent: FilePart => String
  ): BodyWritable[MultipartFormData] = {

    val boundary: String =
      "--------" + scala.util.Random.alphanumeric.take(20).mkString("")

    def encode(str: String) = ByteString.apply(str, charset)

    def formatDataParts(data: Map[String, Seq[String]]) = {
      val dataParts = data.flatMap { case (name, values) =>
        values.map { value =>
          s"--$boundary\r\n${HttpHeaderNames.CONTENT_DISPOSITION}: form-data; name=$name\r\n\r\n$value\r\n"
        }
      }.mkString("")

      encode(dataParts)
    }

    def filePartHeader(file: FilePart) = {
      encode(
        s"--$boundary\r\n${HttpHeaderNames.CONTENT_DISPOSITION}: form-data; name=${file.name}; filename=${file.filenamePart}\r\n${filePartToContent(file)}\r\n"
      )
    }

    BodyWritable[MultipartFormData](
      transform = { (form: MultipartFormData) =>
        // combined data source
        val dataSource: Source[ByteString, _] =
          Source.single(formatDataParts(form.dataParts))

        // files as sources
        val fileSources: Seq[Source[ByteString, _]] = form.files.map { file =>
          val fileSource = FileIO.fromPath(Paths.get(file.path))
          Source
            .single(filePartHeader(file))
            .concat(fileSource)
            .concat(Source.single(encode("\r\n")))
        }

        // file sources combined
        val combinedFileSource =
          fileSources.foldLeft(Source.empty[ByteString])(_.concat(_))

        // all sources concatenated into one
        val finalSource =
          dataSource.concat(combinedFileSource).concat(Source.single(encode(s"--$boundary--")))

        SourceBody(finalSource)
      },
      contentType = s"multipart/form-data; boundary=$boundary"
    )
  }
}