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package monocle.internal

import monocle.Prism

import cats.syntax.order._
import cats.Order

private[monocle] trait Bounded[T] {
  def MinValue: T
  def MaxValue: T
}

private[monocle] object Bounded extends BoundedInstances {
  def apply[T](implicit ev: Bounded[T]): Bounded[T] = ev

  def orderingBoundedSafeCast[S: Order, A: Bounded](unsafeCast: S => A)(reverseCast: A => S): Prism[S, A] =
    Prism[S, A](from =>
      if (from > reverseCast(Bounded[A].MaxValue) || from < reverseCast(Bounded[A].MinValue))
        None
      else
        Some(unsafeCast(from))
    )(reverseCast)
}

private[monocle] trait BoundedInstances {
  implicit val booleanBounded: Bounded[Boolean] = new Bounded[Boolean] {
    val MaxValue: Boolean = true
    val MinValue: Boolean = false
  }

  implicit val byteBounded: Bounded[Byte] = new Bounded[Byte] {
    val MaxValue: Byte = Byte.MaxValue
    val MinValue: Byte = Byte.MinValue
  }

  implicit val charBounded: Bounded[Char] = new Bounded[Char] {
    val MaxValue: Char = Char.MaxValue
    val MinValue: Char = Char.MinValue
  }

  implicit val intBounded: Bounded[Int] = new Bounded[Int] {
    val MaxValue: Int = Int.MaxValue
    val MinValue: Int = Int.MinValue
  }
}