TemporaryLocalFile.scala

import java.io.FileInputStream
import java.nio.file.{ Files, Path }
import cats.Applicative
import cats.implicits._
import cats.effect.{ IO, Resource }
import com.amazonaws.services.s3.model.S3Object
import org.apache.commons.codec.digest.DigestUtils
import org.apache.commons.io.FileUtils

abstract sealed case class TemporaryLocalFile(path: Path) {
  def writeFrom[A](s3Object: S3Object): IO[Unit] =
    IO(FileUtils.copyInputStreamToFile(s3Object.getObjectContent, path.toFile))
}

object TemporaryLocalFile {
  def createResource(
    tempDirectory: String,
    prefix: Option[Prefix],
    suffix: Option[Suffix]
  ): Resource[IO, TemporaryLocalFile] =
    Resource.make(mk(tempDirectory, prefix, suffix))(_.delete.void)

  def mk(tempDirectory: String, prefix: Option[Prefix], suffix: Option[Suffix]): IO[TemporaryLocalFile] = {
    val getOrEmpty: Option[Either[Prefix, Suffix]] => String =
      s => s.map(_.bimap(_.value, _.value).merge).foldMap(identity)

    for {
      tempDir <- IO(Files.createTempDirectory(tempDirectory)) flatTap (path => IO(path.toFile.deleteOnExit()) as path)
      tempPath <- IO(
                   Files.createTempFile(tempDir, getOrEmpty(prefix.map(_.asLeft)), getOrEmpty(suffix.map(_.asRight)))
                 ) flatTap (
                   path => IO(path.toFile.deleteOnExit())
                 )
    } yield new TemporaryLocalFile(tempPath) {}
  }

  // Prefix or suffix that always makes sure its appended or prepended with dots
  abstract sealed case class Prefix(value: String)

  object Prefix {
    def mk(s: String): Prefix =
      if (s.endsWith(".")) {
        new Prefix(s) {}
      } else
        new Prefix(s"${s}.") {}
  }

  abstract sealed case class Suffix(value: String)

  object Suffix {
    def mk(s: String): Suffix =
      if (s.startsWith(".")) {
        new Suffix(s) {}
      } else new Suffix(s".${s}") {}
  }
}