package nova.monadic_sfx.util

final class BoundedStack private (
    val underlying: List[Int],
    val maxSize: Int,
    val sp: Int
) {
  def push(v: Int): Either[String, BoundedStack] =
    if (sp < maxSize) Right(new BoundedStack(v :: underlying, maxSize, sp + 1))
    else Left("overflow")

  def pushAll(v: List[Int]) =
    if (sp + v.length < maxSize)
      Right(new BoundedStack(v ::: underlying, maxSize, sp + v.length))
    else Left("overflow")

  def pop =
    if (sp == 0) Left("Underflow")
    else
      Right(
        underlying(sp) -> new BoundedStack(
          underlying.splitAt(sp)._1,
          maxSize,
          sp - 1
        )
      )
}

object BoundedStack {
  def apply(
      //   defaultValues: List[Int] = List.empty,
      maxSize: Int = 10
      //   sp: Int = 0
  ) =
    new BoundedStack(List.empty, maxSize, 0)

}