package snake
package pong

import PongModel.initialPong

/** m11 pong app: the same wiring as App.scala (streams in, drawings out), reusing the course's modules. */
object PongApp:

  val FRAME_MS_PONG: Long = 30

  private def paddleKey(key: String): Option[Paddle] = key match
    case "ArrowUp" | "w" | "W"   => Some(Paddle.Up)
    case "ArrowDown" | "s" | "S" => Some(Paddle.Down)
    case _                       => None

  def pongKey(isDown: Boolean, key: String): Option[PongAction] =
    paddleKey(key) match
      case Some(p) => Some(if isDown then PongAction.Press(p) else PongAction.Release(p))
      case None    => if isDown && (key == "r" || key == "R") then Some(PongAction.Restart) else None

  lazy val pongActions: Stream[PongAction] =
    Stream
      .interval(FRAME_MS_PONG)
      .map(_ => PongAction.Frame)
      .merge(Stream.keyDowns.filterMap(pongKey(true, _)))
      .merge(Stream.keyUps.filterMap(pongKey(false, _)))

  def pongStates(seed: Long, actions: Stream[PongAction]): Stream[PongState] =
    actions.scan(initialPong(seed))(PongRules.pongUpdate).startWith(initialPong(seed))

  lazy val pongMain: IO[Stream[IO[Unit]]] =
    IO.randomSeed.map(seed => pongStates(seed, pongActions).map(state => IO.drawScene(PongView.pongView(state))))