/// <summary>
/// Unique rule checking for king castling
/// </summary>
/// <param name="king"></param>
/// <returns>returns king positions when castling is possible</returns>
private List<Coords> GetKingCastlingCoords(King king)
{
List<Coords> castling = new List<Coords>();
if (king.HasMoved || king.Checks.Count > 0)
return castling;
List<Coords> availableAttacks = GetAllAvailableCoords(king.Side == PieceColor.White ? PieceColor.Black : PieceColor.White, true);
King enemyKing = king.Side == PieceColor.White ? Board.BlackKing : Board.WhiteKing;
if (!availableAttacks.Contains(king.Coords + 2)
&& !enemyKing.AvailableCoords(Board.Tiles).Contains(king.Coords + 2)
&& !availableAttacks.Contains(king.Coords + 1)
&& Board.Tiles[(int)king.Coords + 4].Piece?.EPiece == EPiece.Rook
&& !((Rook)Board.Tiles[(int)king.Coords + 4].Piece).HasMoved)
castling.Add(king.Coords + 2);
if (!availableAttacks.Contains(king.Coords - 2)
&& !enemyKing.AvailableCoords(Board.Tiles).Contains(king.Coords - 2)
&& !availableAttacks.Contains(king.Coords - 1)
&& Board.Tiles[(int)king.Coords - 3].Piece?.EPiece == EPiece.Rook
&& !((Rook)Board.Tiles[(int)king.Coords - 3].Piece).HasMoved)
castling.Add(king.Coords - 2);
return castling;
}
/// <summary>
/// Coordinates king can move to
/// </summary>
/// <param name="king"></param>
/// <returns></returns>
private List<Coords> GetKingAvailableCoords(King king)
{
return king
.AvailableCoords(Board.Tiles)
.Except(GetAllAvailableCoords(king.Side == PieceColor.White ? PieceColor.Black : PieceColor.White, true, true))
.Except(king.Side == PieceColor.White
? Board.BlackKing.AvailableCoords(Board.Tiles)
: Board.WhiteKing.AvailableCoords(Board.Tiles))
.Except(king.Checks.Where(x => !x.IsAttackBlockable).Select(x => x.Coordinate))
.Concat(GetKingCastlingCoords(king))
.ToList();
}