http4s-demo/src/main/scala/wow/doge/http4sdemo/HelloWorld.scala

package wow.doge.http4sdemo

import cats.Applicative
import cats.implicits._
import io.circe.Encoder
import io.circe.Json
import monix.bio.Task
import org.http4s.EntityEncoder
import org.http4s.circe._

trait HelloWorld[F[_]] {
  def hello(n: HelloWorld.Name): F[HelloWorld.Greeting]
}

object HelloWorld {
  implicit def apply[F[_]](implicit ev: HelloWorld[F]): HelloWorld[F] = ev

  final case class Name(name: String) extends AnyVal

  /** More generally you will want to decouple your edge representations from
    * your internal data structures, however this shows how you can
    * create encoders for your data.
    */
  final case class Greeting(greeting: String) extends AnyVal
  object Greeting {
    implicit val greetingEncoder: Encoder[Greeting] = new Encoder[Greeting] {
      final def apply(a: Greeting): Json = Json.obj(
        ("message", Json.fromString(a.greeting))
      )
    }
    implicit def greetingEntityEncoder[F[_]: Applicative]
        : EntityEncoder[F, Greeting] =
      jsonEncoderOf[F, Greeting]
  }

  def impl: HelloWorld[Task] = new HelloWorld[Task] {
    def hello(n: HelloWorld.Name): Task[HelloWorld.Greeting] =
      Greeting("Hello, " + n.name).pure[Task]
  }
}