Monadic-ScalaFX-Demo/src/main/scala/nova/monadic_sfx/ui/FX.scala

package nova.monadic_sfx.ui

import scala.concurrent.duration._

import cats.effect.Resource
import io.odin.Logger
import monix.bio.Task
import monix.execution.CancelablePromise
import nova.monadic_sfx.concurrent.Schedulers
import nova.monadic_sfx.ui.DefaultScene
import scalafx.application.JFXApp3
import scalafx.application.JFXApp3.PrimaryStage
import monix.bio.UIO
import monix.eval.Coeval
import scalafx.scene.Scene
import scalafx.scene.Parent
import scalafx.Includes._
import monix.bio.IO
import scalafx.scene.Node

final class FX private (
    schedulers: Schedulers,
    delegate: JFXApp3,
    val await: Task[Unit],
    val awaitStop: Task[Unit]
)(implicit logger: Logger[Task]) {
  logger.debug("whoopie")

  def runOnFx[E, A](io: IO[E, A]) = io.executeOn(schedulers.fx.value)

  def addToScene(node: UIO[Node]) =
    runOnFx {
      for {
        p <- node
        _ <- UIO(delegate.stage.scene().getChildren += p)
      } yield ()
    }
}

object FX {
  def resource(
      schedulers: Schedulers,
      stage: Coeval[PrimaryStage],
      initialScene: Coeval[Scene] = DefaultScene(),
      transitionDelay: FiniteDuration = 500.millis
  )(implicit
      logger: Logger[Task]
  ): Resource[Task, FX] =
    Resource
      .make(for {
        _ <- logger.info("Starting FX App")
        makePromise = UIO(CancelablePromise[Unit]())
        startSignal <- makePromise
        stopSignal <- makePromise
        delegate <- Task(new JFXApp3 {
          def start(): Unit = {
            stage = new PrimaryStage {
              scene = initialScene.value()
            }
            startSignal.success(())
          }

          override def stopApp(): Unit = {
            stopSignal.success(())
          }
        })
        fib <-
          Task(delegate.main(Array.empty)).start.executeOn(schedulers.io.value)
        fxApp <- Task(
          new FX(
            schedulers,
            delegate,
            fib.join,
            Task.fromCancelablePromise(stopSignal)
          )
        )
        _ <- Task.fromCancelablePromise(startSignal)
        _ <- Task.sleep(transitionDelay)
        _ <- Task(delegate.stage = stage.value())
          .executeOn(schedulers.fx.value)
          .delayExecution(transitionDelay)
      } yield fxApp -> fib) { case _ -> fib => fib.cancel }
      .map { case a -> _ => a }
}