HttpTsec_11.scala

implicit val loginUserDecoder: Decoder[UsernamePasswordCredentials] = deriveDecoder
implicit val entityLoginUserDecoder: EntityDecoder[IO, UsernamePasswordCredentials] =
  jsonOf[IO, UsernamePasswordCredentials]
def loginRoute(
                auth: BearerTokenAuthenticator[IO, UserId, User],
                checkPassword: UsernamePasswordCredentials => IO[Option[User]]): HttpRoutes[IO] =
  HttpRoutes.of[IO] {
    case req @ POST -> Root / "login" =>
      (for {
        user <- req.as[UsernamePasswordCredentials]
        userOpt <- checkPassword(user)
      } yield userOpt).flatMap {
        case Some(user) => auth.create(user.id).map(auth.embed(Response(Status.Ok), _))
        case None => IO.pure(Response[IO](Status.Unauthorized))
      }
  }