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

package nova.monadic_sfx.util.reactive

import cats.effect.Sync
import monix.bio.Task
import monix.execution.Scheduler
import monix.reactive.Observable
import monix.reactive.OverflowStrategy
import monix.reactive.subjects.ConcurrentSubject

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.deferAction { implicit s =>
      Task {
        val subject = ConcurrentSubject.publish[A](overflowStrategy)

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

            effects.subscribe(subject.onNext _)

            action -> newState
          }
        }

        val obs = subject
          .scan[(A, M)](initialAction -> initialState)(fold)
          .behavior(initialAction -> initialState)
          .refCount

        val res = middlewares.view.reverse.foldLeft(obs) {
          case (obs, middleware) => middleware(obs)
        }

        MonixProSubject.from(
          subject,
          res
        )
      }
    }

  def create[F[_], A, M](
      initialAction: A,
      initialState: M,
      reducer: Reducer[A, M]
  )(implicit s: Scheduler, F: Sync[F]): F[Observable[(A, M)]] =
    F.delay {
      val subject = ConcurrentSubject.publish[A]

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

          effects.subscribe(subject.onNext _)

          action -> newState
        }
      }

      subject
        .scan[(A, M)](initialAction -> initialState)(fold)
        .behavior(initialAction -> initialState)
        .refCount
    }

}