import org.http4s.client.blaze.SimpleHttp1Client
import org.http4s.Status.ResponseClass.Successful
import io.circe.syntax._
import org.http4s._
import org.http4s.headers._
import org.http4s.circe._
import scalaz.concurrent.Task

final case class Login(username: String, password: String)
final case class Token(token: String)
object JsonHelpers {
   import io.circe.generic.auto._
//   implicit val tokenDecoder : Decoder[Token] = Decoder.forProduct1("token")(Token.apply)
//   implicit val tokenEncoder : Encoder[Token] = Encoder.forProduct1("token")(u => u.token)
//   implicit val loginDecoder : Decoder[Login] = Decoder.forProduct2("username", "password")(Login.apply)
//   implicit val loginEncoder : Encoder[Login] = Encoder.forProduct2("username", "password")(u => (u.username, u.password))
   implicit val loginEntityEncoder : EntityEncoder[Login] = jsonEncoderOf[Login]
   implicit val loginEntityDecoder : EntityDecoder[Login] = jsonOf[Login]
   implicit val tokenEntityEncoder: EntityEncoder[Token] = jsonEncoderOf[Token]
   implicit val tokenEntityDecoder : EntityDecoder[Token] = jsonOf[Token]
}

object Http4sTest2 extends App {
   import JsonHelpers._
   val url = "http://www.myserver.com/api/foo"
   val uri = Uri.fromString(url).valueOr(throw _)
   val list = List[Header](`Content-Type`(MediaType.`application/json`), `Accept`(MediaType.`application/json`))
   val request = Request(uri = uri, method = Method.POST)
      .withBody(Login("foo", "bar").asJson)
      .map{r => r.replaceAllHeaders(list :_*)}.run
   val client = SimpleHttp1Client()
   val result = client.fetch[Option[Token]](request){
      case Successful(response) => response.as[Option[Token]]
      case _ => Task(Option.empty[Token])
   }.run
   println(result)
}

object JsonHelpers {
   import io.circe.generic.auto._
   implicit val loginEntityEncoder : EntityEncoder[Login] = jsonEncoderOf[Login]
   implicit val loginEntityDecoder : EntityDecoder[Login] = jsonOf[Login]
   implicit val tokenEntityEncoder: EntityEncoder[Token] = jsonEncoderOf[Token]
   implicit val tokenEntityDecoder : EntityDecoder[Token] = jsonOf[Token]
}

Error:(23, 67) could not find implicit value for parameter decoder: io.circe.Decoder[Login]
   implicit val loginEntityDecoder : EntityDecoder[Login] = jsonOf[Login]