jmonkey-test/src/main/scala/wow/doge/mygame/utils/MonixDirectoryWatcher.scala

package wow.doge.mygame.utils

import cats.kernel.Eq
import cats.syntax.show._
import com.typesafe.scalalogging.Logger
import monix.bio.Task
import monix.execution.Ack
import monix.execution.Cancelable
import monix.execution.cancelables.SingleAssignCancelable
import monix.reactive.Observable
import monix.reactive.OverflowStrategy

object MonixDirectoryWatcher {
  import better.files._
  import io.methvin.better.files._

  private val logger = Logger[MonixDirectoryWatcher.type]

  sealed trait WatchEvent extends Product with Serializable
  final case class CreateEvent(file: File, count: Int) extends WatchEvent
  final case class ModifyEvent(file: File, count: Int) extends WatchEvent
  final case class DeleteEvent(file: File, count: Int) extends WatchEvent
  object WatchEvent {
    implicit val eq = Eq.fromUniversalEquals[WatchEvent]

  }
  @SuppressWarnings(Array("org.wartremover.warts.Equals"))
  def apply(path: os.Path) =
    Task.deferAction(implicit s =>
      Task(
        Observable
          .create[WatchEvent](OverflowStrategy.DropNew(50)) { sub =>
            import sub.scheduler

            val c = SingleAssignCancelable()

            val watcher =
              new RecursiveFileMonitor(
                File(path.toString),
                logger = logger.underlying
              ) {
                override def onCreate(file: File, count: Int) =
                  if (sub.onNext(CreateEvent(file, count)) == Ack.Stop)
                    c.cancel()

                override def onModify(file: File, count: Int) =
                  if (sub.onNext(ModifyEvent(file, count)) == Ack.Stop)
                    c.cancel()

                override def onDelete(file: File, count: Int) =
                  if (sub.onNext(DeleteEvent(file, count)) == Ack.Stop)
                    c.cancel()
              }
            watcher.start()(scheduler)
            c := Cancelable(() => watcher.stop())
            c
          }
          .publish
          .refCount
      )
    )
}