cats.scala

package cats

import cats.Ask.WithS
import kyo.*
import kyo.TypeMap
import kyo.kernel.ContextEffect

sealed trait Ask[R[_[_]]] extends ContextEffect[TypeMap[R[Ask.AnyS]]]

object Ask:

  private trait AnyT[AnyF[_]]
  private def erasedTag[R[_[_]]] = Tag[Ask[AnyT]].asInstanceOf[Tag[Ask[R]]]

  type WithS[-S]    = [A] =>> A < S
  type Fix[R[_[_]]] = R[WithS[Ask[R]]]

  private[cats] type AnyS = WithS[Any]

  def use[R[_[_]]](using frame: Frame)[A, S](f: Fix[R] => A < S)(using tag: Tag[R[AnyS]]): A < (Ask[R] & S) =
    ContextEffect.suspendWith(erasedTag[R]): map =>
      f(map.asInstanceOf[TypeMap[R[AnyS]]].get(using tag).asInstanceOf[Fix[R]])

  def get[R[_[_]]](using frame: Frame, tag: Tag[R[AnyS]]): Fix[R] < Ask[R] = use[R](identity)

  def run[R[_[_]], S1](r: R[WithS[S1]])[A, S2](a: A < (Ask[R] & S2))(using tag: Tag[R[AnyS]], frame: Frame): A < (S1 & S2) =
    val env: TypeMap[R[AnyS]] = TypeMap(r.asInstanceOf)
    ContextEffect.handle(erasedTag[R], env, _.union(env))(a)

trait Console[F[_]]:
  def read: F[String]
  def printLine(line: String): F[Unit]

trait Logger[F[_]]:
  def log(level: String)(message: String): F[Unit]

val comp: String < (Ask[Console] & Ask[Logger] & Sync) =
  for
    console <- Ask.get[Console]
    logger  <- Ask.get[Logger]
    _       <- logger.log("Debug")("Start teletype example")

    _       <- kyo.Console.printLine("Hello from Kyo")

    _       <- console.printLine("Hello, World!")
    _       <- console.printLine("What is your name?")
    name    <- console.read
    _       <- console.printLine(s"Hello $name!")
  yield name

val soutConsole: Console[Ask.WithS[Sync]] = new Console[WithS[Sync]]:
  override def read: String < Sync                  = kyo.Console.readLine.orPanic
  override def printLine(line: String): Unit < Sync = kyo.Console.printLine(line)

val soutLogger: Logger[Ask.WithS[Sync]] = new Logger[WithS[Sync]]:
  override def log(level: String)(message: String): Unit < Sync = kyo.Console.printLine(s"[$level]: $message")

object App extends KyoApp:
  comp.handle(
    Ask.run(soutLogger),
    Ask.run(soutConsole),
    run
  )