/// <summary>
/// Can any friendly piece block the attacker?
/// </summary>
/// <param name="threateningPiece"></param>
/// <returns></returns>
private bool CanFriendlyPieceMoveBetweenKingAndAttacker(IPiece threateningPiece, IBoardState boardState)
{
switch (threateningPiece)
{
// all cases fall through
case IKnight _: // knights jump pieces, cannot move between
case IPawn _: // pawns attack in an adjacent square, cannot move between
case IKing _: // king will never be checking another king.
return(false);
}
foreach (IPiece piece in ActivePlayerPieces.Where(p => !(p is IKing) && p.Location != ChessPosition.None))
{
piece.GenerateMoves(boardState);
// use a copy of the MoveSet to prevent the collection from being modified in the following loop
IBoardState copyOfMoveSet = ModelLocator.BoardState;
copyOfMoveSet.Add(piece.MoveSet);
foreach (ChessPosition location in copyOfMoveSet)
{
var move = ModelLocator.CreateMove(piece.Location, location);
var isMoveLegal = IsMoveLegal(piece, move, boardState);
var isKingInCheckAfterMove = DoesPotentialMoveLeaveKingInCheck(move);
if (isMoveLegal && !isKingInCheckAfterMove)
{
return(true);
}
}
}
return(false);
}
/// <summary>
/// Determine if the king can move out of check by capturing a piece or simply moving.
/// </summary>
private bool CanKingMoveOrCaptureOutOfCheck(IKing king, IBoardState gameBoardState)
{
var canKingMoveOutOfCheck = false;
var canKingCaptureOutOfCheck = false;
// 1.) Can the king move or capture out of check?
foreach (ChessPosition position in king.ThreatenSet)
{
IMove move = ModelLocator.CreateMove(king.Location, position);
ICapture capture = ModelLocator.CreateCapture(king.Location, position);
canKingMoveOutOfCheck |= IsMoveLegal(king, move, gameBoardState);
canKingCaptureOutOfCheck |= IsCaptureLegal(king, capture, gameBoardState);
}
return(canKingMoveOutOfCheck || canKingCaptureOutOfCheck);
}