PartialState.scala

package chesednow.requests.sjs

import japgolly.scalajs.react.Callback
import japgolly.scalajs.react.vdom.VdomNode

import cats.implicits._
import monocle.{Iso, Prism}

trait PartialStateBase[V] {
  type State
  def initial: State
  def prism: Prism[State, V]

  type Settable = (State, V => Callback)
  type Renderer = Settable => VdomNode
}
abstract class PartialState[V, S](override val initial: S) extends PartialStateBase[V] {
  override type State = S
}
object PartialState {
  def apply[V, S](empty: S)(getOption: S => Option[V])(reverseGet: V => S): PartialState[V, S] = {
    new PartialState[V, S](empty) {
      override val prism = Prism(getOption)(reverseGet)
    }
  }

  def singleton[V](v: V): PartialState[V, Unit] =
    apply(())(_ => Some(v))(_ => ())

  def fromIso[V, S](iso: Iso[V, S]): PartialState[V, Option[S]] =
    apply(Option.empty[S])(_.map(iso.reverseGet))(v => Some(iso.get(v)))

  def option[V]: PartialState[V, Option[V]] =
    apply(Option.empty[V])(identity)(Some(_))

  def simple[V](empty: V): PartialState[V, V] =
    apply(empty)(Some(_))(identity)

  def tuple2[V, V1, V2, S1, S2](iso: Iso[V, (V1, V2)])
                               (c1: PartialState[V1, S1],
                                c2: PartialState[V2, S2]): PartialState[V, (S1, S2)] =
    apply((c1.initial, c2.initial)) { case (s1, s2) =>
      (c1.prism.getOption(s1), c2.prism.getOption(s2)).tupled.map(iso.reverseGet)
    } { v =>
      val (v1, v2) = iso.get(v)
      (c1.prism.reverseGet(v1), c2.prism.reverseGet(v2))
    }

  def tuple3[V, V1, V2, V3, S1, S2, S3](iso: Iso[V, (V1, V2, V3)])
                                       (c1: PartialState[V1, S1],
                                        c2: PartialState[V2, S2],
                                        c3: PartialState[V3, S3]): PartialState[V, (S1, S2, S3)] =
    apply((c1.initial, c2.initial, c3.initial)) { case (s1, s2, s3) =>
      (c1.prism.getOption(s1), c2.prism.getOption(s2), c3.prism.getOption(s3)).tupled.map(iso.reverseGet)
    } { v =>
      val (v1, v2, v3) = iso.get(v)
      (c1.prism.reverseGet(v1), c2.prism.reverseGet(v2), c3.prism.reverseGet(v3))
    }
}