lila/modules/importer/src/main/Chess960.scala

package lila.importer

import chess._

private object Chess960 {

  def isStartPosition(board: Board) = board valid true && {

    def rankMatches(f: Option[Piece] => Boolean)(rank: Int) =
      (1 to 8) forall { file =>
        f(board(file, rank))
      }

    rankMatches {
      case Some(Piece(White, King | Queen | Rook | Knight | Bishop)) => true
      case _                                                         => false
    }(1) &&
    rankMatches {
      case Some(Piece(White, Pawn)) => true
      case _                        => false
    }(2) &&
    List(3, 4, 5, 6).forall(rankMatches(_.isEmpty)) &&
    rankMatches {
      case Some(Piece(Black, Pawn)) => true
      case _                        => false
    }(7) &&
    rankMatches {
      case Some(Piece(Black, King | Queen | Rook | Knight | Bishop)) => true
      case _                                                         => false
    }(8)
  }

  def fixVariantName(v: String) = v.toLowerCase match {
    case "chess 960"   => "chess960"
    case "fisherandom" => "chess960" // I swear, sometimes...
    case _             => v
  }
}