Monadic-ScalaFX-Demo/src/main/scala/nova/monadic_sfx/implicits/JavaFxMonixObservables.scala

package nova.monadic_sfx.implicits

import javafx.beans.property.ObjectProperty
import javafx.collections.ObservableList
import javafx.scene.{input => jfxsi}
import javafx.{event => jfxe}
import monix.bio.Task
import monix.execution.Ack
import monix.execution.Cancelable
import monix.execution.Scheduler
import monix.reactive.Observable
import monix.reactive.Observer
import monix.reactive.OverflowStrategy
import monix.tail.Iterant
import monix.{eval => me}
import scalafx.Includes._
import scalafx.beans.property.Property
import scalafx.beans.value.ObservableValue
import scalafx.collections.ObservableBuffer
import scalafx.scene.Scene
import scalafx.scene.control.ButtonBase

object JavaFXMonixObservables {

  implicit final class SceneObservables(private val scene: Scene)
      extends AnyVal {

    def observableMousePressed(): Observable[jfxsi.MouseEvent] = {
      import monix.execution.cancelables.SingleAssignCancelable
      Observable.create(OverflowStrategy.Unbounded) { sub =>
        val c = SingleAssignCancelable()
        val l = new jfxe.EventHandler[jfxsi.MouseEvent] {
          override def handle(event: jfxsi.MouseEvent): Unit = {
            if (sub.onNext(event) == Ack.Stop) c.cancel()
          }
        }

        scene.onMousePressed = l
        c := Cancelable(() =>
          scene.removeEventHandler(
            jfxsi.MouseEvent.MOUSE_PRESSED,
            l
          )
        )
        c
      }
    }

    def observableMouseDragged(): Observable[jfxsi.MouseEvent] = {
      import monix.execution.cancelables.SingleAssignCancelable
      Observable.create(OverflowStrategy.Unbounded) { sub =>
        val c = SingleAssignCancelable()
        val l = new jfxe.EventHandler[jfxsi.MouseEvent] {
          override def handle(event: jfxsi.MouseEvent): Unit = {
            if (sub.onNext(event) == Ack.Stop) c.cancel()
          }
        }

        scene.onMouseDragged = l
        c := Cancelable(() =>
          scene.removeEventHandler(
            jfxsi.MouseEvent.MOUSE_DRAGGED,
            l
          )
        )
        c
      }
    }
  }

  // implicit final class BindObs[T, J](private val prop: Property[T, J])
  //     extends AnyVal {
  //   def -->(op: Observer[T]) = {
  //     op.onNext(prop.value)
  //   }

  //   def <--(obs: Observable[T])(implicit s: Scheduler) = {
  //     obs.doOnNext(v => me.Task(prop.value = v)).subscribe()
  //   }

  //   def observableChange[J1 >: J]()
  //       : Observable[(ObservableValue[T, J], J1, J1)] = {
  //     import monix.execution.cancelables.SingleAssignCancelable
  //     Observable.create(OverflowStrategy.Unbounded) { sub =>
  //       val c = SingleAssignCancelable()

  //       val canc = prop.onChange((a, b, c) => sub.onNext((a, b, c)))

  //       c := Cancelable(() => canc.cancel())
  //       c
  //     }
  //   }
  // }

  implicit final class BindObs2[A](private val prop: ObjectProperty[A])
      extends AnyVal {

    // def -->(sub: Var[A]) =
    //   prop.onChange((a, b, c) => sub := c)

    def -->(sub: Observer[A]) =
      prop.onChange((a, b, c) => if (c != null) sub.onNext(c))

    // def -->[J1 >: A, T](
    //     op: Observable[J1] => me.Task[T]
    // )(implicit s: Scheduler) = {
    //   op(prop.observableChange().map(_._3)).runToFuture
    // }

    def <--(obs: Observable[A])(implicit s: Scheduler) = {
      obs.doOnNext(v => me.Task(prop() = v)).subscribe()
    }

    def observableChange[J1 >: A]()
        : Observable[(ObservableValue[A, A], J1, J1)] = {
      import monix.execution.cancelables.SingleAssignCancelable
      Observable.create(OverflowStrategy.Unbounded) { sub =>
        val c = SingleAssignCancelable()

        val canc = prop.onChange((a, b, c) => sub.onNext((a, b, c)))

        c := Cancelable(() => canc.cancel())
        c
      }
    }
  }

  implicit final class ObjectPropertyObservableListExt[A](
      private val prop: ObjectProperty[ObservableList[A]]
  ) extends AnyVal {
    def <--(obs: Observable[Seq[A]])(implicit s: Scheduler) = {
      obs.doOnNext(v => me.Task(prop() = ObservableBuffer.from(v))).subscribe()
    }

    def -->(sub: Observer[A])(implicit s: Scheduler) =
      prop.onChange((a, b, c) =>
        if (c != null)
          Iterant[Task]
            .fromIterable(c.toIterable)
            .consume
            .use(consume(sub, _))
            .runToFuture
      )

    private def loop(sub: Observer[A], it: Iterator[A]): Task[Unit] =
      if (it.hasNext) {
        val next = it.next()
        Task.deferFuture(sub.onNext(next)).flatMap {
          case Ack.Continue => loop(sub, it)
          case Ack.Stop     => Task.unit
        }
      } else Task.unit

    private def consume(
        sub: Observer[A],
        consumer: Iterant.Consumer[Task, A]
    ): Task[Unit] =
      consumer.pull.flatMap {
        case Left(value) => Task.unit
        case Right(value) =>
          Task.deferFuture(sub.onNext(value)).flatMap {
            case Ack.Continue => consume(sub, consumer)
            case Ack.Stop     => Task.unit
          }
      }

  }

  implicit final class OnActionObservable(
      private val button: ButtonBase
  ) extends AnyVal {
    // def -->[T](
    //     op: Observable[jfxe.ActionEvent] => me.Task[T]
    // )(implicit s: Scheduler) = {
    //   op(button.observableAction()).runToFuture
    // }

    // def -->(
    //     sub: ConcurrentSubject[jfxe.ActionEvent, jfxe.ActionEvent]
    // ) = {
    //   button.onAction = value => sub.onNext(value)
    // }

    def observableAction(): Observable[jfxe.ActionEvent] = {
      import monix.execution.cancelables.SingleAssignCancelable
      Observable.create(OverflowStrategy.Unbounded) { sub =>
        val c = SingleAssignCancelable()
        val l = new jfxe.EventHandler[jfxe.ActionEvent] {
          override def handle(event: jfxe.ActionEvent): Unit = {
            if (sub.onNext(event) == Ack.Stop) c.cancel()
          }
        }

        button.onAction = l
        c := Cancelable(() =>
          button.removeEventHandler(
            jfxe.ActionEvent.ACTION,
            l
          )
        )
        c
      }
    }
  }
}