package snake
package life

import LifeModel.*

/** m13 life app: the same wiring as Snake and Pong, with a third kind of input, the mouse. */
object LifeApp:

  val GEN_MS: Long = 150

  def lifeKey(key: String): Option[LifeAction] = key match
    case " "       => Some(LifeAction.TogglePause)
    case "n" | "N" => Some(LifeAction.Step)
    case "c" | "C" => Some(LifeAction.Clear)
    case "r" | "R" => Some(LifeAction.Randomize)
    case _         => None

  // The pixel is checked before dividing: integer division rounds towards zero, so -1 / 16 would be cell 0.
  def lifeClick(x: Int, y: Int): Option[LifeAction] =
    if x >= 0 && y >= 0 && x / LCELL < LW && y / LCELL < LH then Some(LifeAction.Toggle(Point(x / LCELL, y / LCELL)))
    else None

  lazy val lifeActions: Stream[LifeAction] =
    Stream
      .interval(GEN_MS)
      .map(_ => LifeAction.Frame)
      .merge(Stream.keyDowns.filterMap(lifeKey))
      .merge(Stream.clicks.filterMap(lifeClick(_, _)))

  def lifeStates(seed: Long, actions: Stream[LifeAction]): Stream[LifeState] =
    actions.scan(initialLife(seed))(LifeRules.lifeUpdate).startWith(initialLife(seed))

  lazy val lifeMain: IO[Stream[IO[Unit]]] =
    IO.randomSeed.map(seed =>
      lifeStates(seed, lifeActions).map(state => IO.drawScene(LifeView.lifeView(state))).clampTime(App.MAX_GAP_MS)
    )