playframework/playframework

package common

import java.io.File

import javax.inject.Inject
import play.api.libs.ws.{WSClient, WSResponse}

import scala.concurrent.{ExecutionContext, Future}
import akka.stream.Materializer
import akka.stream.javadsl.Sink
import akka.util.ByteString

class FileDownloader @Inject() (ws: WSClient)(
    implicit mat: Materializer,
    ec: ExecutionContext
) {
  def download(url: String): Future[Unit] = Future {
    val file = File.createTempFile("stream-to-file-", ".txt")
    val futureResponse: Future[WSResponse] =
      ws.url(url).withMethod("GET").stream()

    val downloadedFile: Future[File] = futureResponse.flatMap { res =>
      val outputStream = java.nio.file.Files.newOutputStream(file.toPath)

      val sink = Sink.foreach[ByteString] { bytes =>
        outputStream.write(bytes.toArray)
      }

      res.bodyAsSource
        .runWith(sink)
        .andThen {
          case result =>
            outputStream.close()
            result.get
        }
        .map(_ => file)
    }
  }
}