AsyncCallbackInstances.scala

object AsyncCallbackInstances {
  implicit val asyncCallbackAsync: Async[AsyncCallback] = new Async[AsyncCallback] {
    override def async[A](k: (Either[Throwable, A] => Unit) => Unit): AsyncCallback[A] =
      AsyncCallback((cb: Try[A] => Callback) => Callback(k(r => cb(r.toTry).runNow())))

    override def asyncF[A](k: (Either[Throwable, A] => Unit) => AsyncCallback[Unit]): AsyncCallback[A] =
      AsyncCallback((cb: Try[A] => Callback) => k(r => cb(r.toTry).runNow()).toCallback)

    override def suspend[A](thunk: => AsyncCallback[A]): AsyncCallback[A] =
      AsyncCallback.byName(thunk)

    override def bracketCase[A, B](acquire: AsyncCallback[A])(use: A => AsyncCallback[B])(
        release: (A, ExitCase[Throwable]) => AsyncCallback[Unit]): AsyncCallback[B] =
      acquire.flatMap { a =>
        use(a).attempt.flatMap {
          case Right(b) => release(a, ExitCase.Completed).map(_ => b)
          case Left(t)  => release(a, ExitCase.Error(t)).flatMap(_ => AsyncCallback.throwException(t))
        }
      }

    override def raiseError[A](e: Throwable): AsyncCallback[A] =
      AsyncCallback.throwException(e)

    override def handleErrorWith[A](fa: AsyncCallback[A])(f: Throwable => AsyncCallback[A]): AsyncCallback[A] =
      fa.attempt.flatMap {
        case Right(a) => AsyncCallback.pure(a)
        case Left(t)  => f(t)
      }

    override def pure[A](a: A): AsyncCallback[A] =
      AsyncCallback.pure(a)

    override def flatMap[A, B](fa: AsyncCallback[A])(f: A => AsyncCallback[B]): AsyncCallback[B] =
      fa.flatMap(f)

    override def tailRecM[A, B](a: A)(f: A => AsyncCallback[Either[A, B]]): AsyncCallback[B] =
      AsyncCallback.tailrec(a)(f)
  }
}