private static Move DetermineMove(Board board, UCIChessMove uciMove)
{
string from = uciMove.From;
string to = uciMove.To;
var fromPos = Position.Parse(from);
var toPos = Position.Parse(to);
var fromPiece = board[fromPos];
int fileDiff = Math.Abs((int)fromPiece.Position.File - (int)toPos.File);
if (fromPiece.Type == PieceType.King && (fileDiff == 3 || fileDiff == 4))
{
King king = (King)fromPiece;
Rook rook;
if (fileDiff == 4)
{
rook = (Rook)board[File.A, fromPiece.Position.Rank];
}
else
{
rook = (Rook)board[File.H, fromPiece.Position.Rank];
}
return(MoveBuilder.CreateCastleMove(king, rook));
}
if (uciMove.PromotionChar != null)
{
string promotionChar = uciMove.PromotionChar.ToUpper();
var promotionType = (from p in (PieceType[])Enum.GetValues(typeof(PieceType))
where p.ToNotationLetter().ToUpper() == promotionChar.ToUpper()
select p).First();
var promotionMoves = MoveBuilder.CreatePromotionMoves((Pawn)fromPiece, toPos, board[toPos] != null);
return((from m in promotionMoves
where m.Promotion.NewPieceType.Type == promotionType
select m).First());
}
// Check for en passant
var existingPieceRank = fromPiece.Position.Rank;
var isCorrectRank = fromPiece.Color == PieceColor.Black ? existingPieceRank == Rank._4 : existingPieceRank == Rank._5;
try
{
int vertDir = fromPiece.Color == PieceColor.White ? -1 : 1;
var existingPieceTo = board[toPos];
var capturedPiecePos = toPos.MoveVert(vertDir);
var capturedPiece = board[capturedPiecePos];
if (capturedPiece.Color == fromPiece.Color.Opposite() &&
capturedPiece.MoveHistory.Count == 1)
{
// This is an en passant
return(MoveBuilder.CreateEnPassantMove((Pawn)fromPiece, toPos, capturedPiecePos));
}
}
catch { }
// Only other option is that this is a normal move.
return(MoveBuilder.CreateNormalMove(fromPiece, toPos, board[toPos] != null));
}
private Move CheckCastleWithRookLocation(Board board, Position rookPos)
{
var pieceInPos = board[rookPos];
if (pieceInPos == null)
{
return(null);
}
if (pieceInPos.Type != PieceType.Rook)
{
return(null);
}
if (pieceInPos.Color != this.Color)
{
return(null);
}
if (pieceInPos.MoveHistory != null && pieceInPos.MoveHistory.Count > 0)
{
return(null);
}
int startFile = (int)rookPos.File;
int myFile = (int)Position.File;
int increment = (myFile > startFile) ? 1 : -1;
// Rook is eligible. Check pieces in between.
for (int f = startFile + increment; f != myFile; f += increment)
{
var pieceInFile = board[(File)f, Position.Rank];
if (pieceInFile != null)
{
return(null);
}
bool kingWillPassThroughThisSquare = Math.Abs(myFile - f) <= 2;
if (kingWillPassThroughThisSquare)
{
var fakeMove = MoveBuilder.CreateNormalMove(this,
new Position((File)f, Position.Rank), false);
if (board.DoesMovePutKingInCheck(this.Color, fakeMove))
{
return(null);
}
}
}
return(MoveBuilder.CreateCastleMove(this, (Rook)pieceInPos));
}