Monadic-ScalaFX-Demo/src/main/scala/nova/monadic_sfx/util/reactive/store/Store.scala

package nova.monadic_sfx.util.reactive.store

import monix.bio.Task
import monix.eval.Coeval
import monix.reactive.Observer
import monix.reactive.OverflowStrategy
import monix.reactive.subjects.ConcurrentSubject
import cats.effect.Resource
import monix.{eval => me}
import monix.catnap.ConcurrentQueue
import nova.monadic_sfx.util.IOUtils
import monix.reactive.Observable
import io.odin.Logger
import nova.monadic_sfx.implicits._

object Store {
  def createL[A, M](
      initialAction: A,
      initialState: M,
      reducer: Reducer[A, M],
      middlewares: Seq[Middleware[A, M]] = Seq.empty,
      overflowStrategy: OverflowStrategy.Synchronous[A] =
        OverflowStrategy.DropOld(50)
  ): Task[Store[A, M]] =
    Task.deferAction { implicit s =>
      Task {
        val subject = ConcurrentSubject.publish[A](overflowStrategy)

        val fold: ((A, M), A) => Coeval[(A, M)] = {
          case ((_, state), action) =>
            Coeval {
              val (newState, effects) = reducer(state, action)

              effects.subscribe(subject.onNext _)

              action -> newState
            }
        }

        val obs = subject
          .scanEval0F[Coeval, (A, M)](
            Coeval.pure(initialAction -> initialState)
          )(fold)

        val res = middlewares
          .foldLeft(obs) {
            case (obs, middleware) => middleware(obs)
          }
          .doOnNextF(i => Coeval(println(s"Emitted item 1: $i")))
          .behavior(initialAction -> initialState)
          .refCount

        res.subscribe(Observer.empty)

        // .doOnNextF(i => Coeval(println(s"Emitted item 2: $i")))

        MonixProSubject.from(
          subject,
          res
        )
      }
    }

  // : Resource[Task, Store[A, M]]
  def backpressured[A, M](
      initialAction: A,
      initialState: M,
      reducer: Reducer[A, M],
      logger: Logger[Task],
      middlewares: Seq[Middleware[A, M]] = Seq.empty
  ) = {

    for {
      queue <- ConcurrentQueue[Task].bounded[A](10)
      source <- Task.deferAction(implicit s =>
        Task {
          val fold: ((A, M), A) => Task[(A, M)] = {
            case ((_, state), action) =>
              for {
                _ <- Task.unit
                (newState, effects) = reducer(state, action)
                _ <-
                  effects
                    .doOnNextF(queue.offer)
                    .completedL
                    .toIO
                // .start

              } yield action -> newState
          }

          val obs = Observable
            .repeatEvalF(queue.poll)
            .scanEval0F[Task, (A, M)](
              Task.pure(initialAction -> initialState)
            )(fold)

          val res =
            // middlewares
            //   .foldLeft(obs) {
            //     case (obs, middleware) => middleware(obs)
            //   }
            obs
              .doOnNextF(i => logger.debug(s"Emitted item 1: $i"))
              .behavior(initialAction -> initialState)
              .refCount

          // res.subscribe(Observer.empty)

          // .doOnNextF(i => Coeval(println(s"Emitted item 2: $i")))

          res
        }
      )
    } yield new MyStore(Sink2.concurrentQueue(queue), source)

  }

}

final class MyStore[A, M](
    val sink: Sink2[A],
    val source: Observable[(A, M)]
)