public void SetGameStateSnapshot(GameState oldGameState, GameState newGameState, StateInfo stateInfo, int piecePosition, int newPiecePosition)
{
var fenPosition = getFENPosition(newGameState.Squares);
var castlingAvailability = getCastlingAvailability(newGameState, newGameState.CastlingAvailability, piecePosition, newPiecePosition);
var enPassantCoord = getEnPassantCoord(newGameState.Squares, newGameState.ActiveColor, piecePosition, newPiecePosition);
var newHalfmoveClock = getHalfmoveClock(oldGameState.Squares, oldGameState.HalfmoveClock, piecePosition, newPiecePosition);
var activeColor = newGameState.ActiveColor.Reverse();
newGameState.PiecePlacement = fenPosition;
newGameState.ActiveColor = activeColor;
newGameState.CastlingAvailability = castlingAvailability;
newGameState.EnPassantTargetSquare = enPassantCoord;
if (enPassantCoord != "-")
{
newGameState.EnPassantTargetPosition = NotationEngine.CoordinateToPosition(enPassantCoord);
}
newGameState.HalfmoveClock = newHalfmoveClock;
//better to calculate this value after setting the ActiveColor
var fullmoveNumber = getFullmoveNumber(newGameState.FullmoveNumber, newGameState.ActiveColor);
newGameState.FullmoveNumber = fullmoveNumber;
var pgnMove = stateInfo.IsPawnPromotion
? _pgnService.SquarePairToPGNMove(oldGameState, oldGameState.ActiveColor, piecePosition, newPiecePosition, stateInfo.PawnPromotedTo)
: _pgnService.SquarePairToPGNMove(oldGameState, oldGameState.ActiveColor, piecePosition, newPiecePosition);
newGameState.PGNMoves.Add(pgnMove);
newGameState.PGN = getUpdatedPGN(newGameState, oldGameState.ActiveColor, fullmoveNumber, pgnMove);
}
private string squarePairToPGNMove(GameState gameState, Color playerColor, string startSquare, string endSquare)
{
var startPos = NotationEngine.CoordinateToPosition(startSquare);
var endPos = NotationEngine.CoordinateToPosition(endSquare);
return(squarePairToPGNMove(gameState, playerColor, startPos, endPos));
}
private OperationResult verifyMove(GameState gameState, int piecePosition, int newPiecePosition)
{
var oldSquare = gameState.Squares.GetSquare(piecePosition);
var attacks = gameState.Attacks.GetPositionAttacksOnPosition(piecePosition, newPiecePosition);
if (!attacks.Any())
{
return(OperationResult.Fail($"Can't find an attack by this piece ({ oldSquare.Index } : { oldSquare.Piece.PieceType }) on this position ({ newPiecePosition })."));
}
var badPawnAttacks = attacks.Where(a =>
a.AttackingSquare.Index == piecePosition &&
a.Index == newPiecePosition &&
a.Piece == null &&
a.MayOnlyMoveHereIfOccupiedByEnemy
);
if (badPawnAttacks.Any())
{
if (
badPawnAttacks.Count() > 1 ||
gameState.EnPassantTargetSquare == "-" ||
newPiecePosition != NotationEngine.CoordinateToPosition(gameState.EnPassantTargetSquare)
)
{
return(OperationResult.Fail($"This piece can only move here if the new square is occupied. ({ oldSquare.Index } : { oldSquare.Piece.PieceType }) on this position ({ newPiecePosition })."));
}
}
return(OperationResult.Ok());
}
public OperationResult <GameState> MakeMove(GameState gameState, string beginning, string destination, PieceType?piecePromotionType = null)
{
var pos1 = NotationEngine.CoordinateToPosition(beginning);
var pos2 = NotationEngine.CoordinateToPosition(destination);
return(this.MakeMove(gameState, pos1, pos2, piecePromotionType));
}
private Square pgnLength4(GameState gameState, IEnumerable <AttackedSquare> potentialPositions, string newPgnMove)
{
var ambiguityResolver = newPgnMove[1];
var isRank = IsRank(ambiguityResolver); // this could be either a rank or a file
List <int> ambiguityResolutionSet;
if (isRank)
{
int rank = 0;
Int32.TryParse(ambiguityResolver.ToString(), out rank);
ambiguityResolutionSet = this._orthogonalService.GetEntireRank(rank - 1);// needs to be using zero-based rank offset
}
else
{
var iFile = NotationEngine.FileToInt(ambiguityResolver);
ambiguityResolutionSet = this._orthogonalService.GetEntireFile(iFile);
}
var intersection = potentialPositions.Select(a => a.AttackingSquare.Index).Intersect(ambiguityResolutionSet);
if (intersection.Count() > 1)
{
throw new Exception("There should not be more than one item found here.");
}
return(gameState.Squares.GetSquare(intersection.First()));
}
private string squarePairToPGNMove(GameState gameState, Color playerColor, int startPos, int endPos)
{
var destinationSquare = gameState.Squares.GetSquare(endPos);
var isCapture = destinationSquare.Occupied && destinationSquare.Piece.Color != playerColor;
var attacks = gameState.Attacks.Where(a => a.AttackingSquare.Index == startPos);
if (attacks == null || !attacks.Any() || !attacks.Any(a => a.Index == endPos))
{
throw new Exception("No attacks can be made on this ending square.");
}
var square = gameState.Squares.GetSquare(startPos);
if (!square.Occupied)
{
throw new Exception("Bad coordinates were given.");
}
var piece = square.Piece;
if (piece.Color != playerColor)
{
throw new Exception("Color doesn't match given positions.");
}
var notationPiece = char.ToUpper(piece.Identity);
var coord = NotationEngine.PositionToCoordinate(endPos);
var pgnMove = getPgnMove(notationPiece, piece, coord, startPos, endPos, isCapture, gameState);
return(pgnMove);
}
private bool isValidKnightMove(int position, int tempPosition, int file, int rank)
{
var isValidCoordinate = GeneralEngine.IsValidCoordinate(tempPosition);
if (!isValidCoordinate)
{
return(false);
}
var tempCoord = NotationEngine.PositionToCoordinate(tempPosition);
var tempFile = NotationEngine.FileToInt(tempCoord[0]);
var tempRank = (int)tempCoord[1];
var fileDiff = Math.Abs(tempFile - file);
var rankDiff = Math.Abs(tempRank - rank);
if (fileDiff > 2 || fileDiff < 1)
{
return(false);
}
if (rankDiff > 2 || rankDiff < 1)
{
return(false);
}
return(true);
}
private (int position, char promotedPiece, bool isCastle) getPositionFromPGNMove(string pgnMove, Color playerColor, string enPassantTargetSquare)
{
var promotedPiece = '-';
var isCastle = castlePattern.IsMatch(pgnMove);
if (isCastle)
{
var castleResult = getCastlePositionFromPGNMove(pgnMove, playerColor, promotedPiece);
return(castleResult.position, castleResult.promotedPiece, true);
}
var isEnPassant = false;
if (enPassantTargetSquare != "-")
{
var isCapture = pgnMove[1] == 'x';
if (isCapture)
{
var len = pgnMove.Length;
if (len >= 6)
{
var rightSide = pgnMove.Substring(4, len - 4);
isEnPassant = rightSide.Contains("ep") || rightSide.Contains("e.p.");
if (isEnPassant)
{
return(NotationEngine.CoordinateToPosition(enPassantTargetSquare), promotedPiece, false);
}
}
}
}
// could be a pawn promotion
var pawnCapturePromotion = pawnCapturePromotionPattern.IsMatch(pgnMove);
var pawnPromotion = pawnPromotionPattern.IsMatch(pgnMove);
if (pawnCapturePromotion || pawnPromotion)
{
// yeah, it is a pawn promotion
promotedPiece = pgnMove.Last();
if (promotedPiece == '+' || promotedPiece == '#')
{
promotedPiece = pgnMove.Substring(pgnMove.Length - 2, 1)[0];
}
var dest = pawnCapturePromotion ? pgnMove.Substring(2, 2) : pgnMove.Substring(0, 2);
return(NotationEngine.CoordinateToPosition(dest), promotedPiece, false);
}
// probably just a regular move
pgnMove = pgnMove.Replace("x", "").Replace("+", "").Replace("#", "");
// not sure why I needed this
var x = 2;
if (pgnMove.Contains("="))
{
x = 4;
throw new Exception("I didn't think this could happen, so I tested it with an exception.");
}
return(NotationEngine.CoordinateToPosition(pgnMove.Substring(pgnMove.Length - x, 2)), promotedPiece, false);
}
private Square pgnLength5(GameState gameState, string newPgnMove)
{
var _file = NotationEngine.FileToInt(newPgnMove[1]);
var _rank = 0;
Int32.TryParse(newPgnMove[2].ToString(), out _rank);
var pos = NotationEngine.CoordinatePairToPosition(_file, _rank);
return(gameState.Squares.GetSquare(pos));
}
private Square getOriginationPositionForCastling(GameState gameState, Color color)
{
var rank = color == Color.White ? 1 : 8;
var file = 4;
var fileChar = NotationEngine.IntToFile(file);
var coord = string.Concat(fileChar, rank);
var origination = NotationEngine.CoordinateToPosition(coord);
return(gameState.Squares.GetSquare(origination));
}
private Square pgnLength3(IEnumerable <AttackedSquare> potentialPositions, string newPgnMove)
{
var ambiguityResolver = newPgnMove[0];
var files = this._orthogonalService.GetEntireFile(NotationEngine.FileToInt(ambiguityResolver)); // this will always be a file if this is a pawn
var potentialSquares = potentialPositions.Where(a => files.Contains(a.AttackingSquare.Index)).ToList();
if (potentialSquares.Count() > 1)
{
throw new Exception("There should not be more than one item found here.");
}
return(potentialSquares.First().AttackingSquare);
}
public OperationResult <GameState> MakeMove(GameState gameState, string pgnMove)
{
var pair = _pgnService.PGNMoveToSquarePair(gameState, pgnMove);
//todo: what about piece promotion?
if (pair.promotedPiece == '-')
{
return(this.MakeMove(gameState, pair.piecePosition, pair.newPiecePosition));
}
var promotedPieceType = NotationEngine.GetPieceTypeFromCharacter(pair.promotedPiece);
return(this.MakeMove(gameState, pair.piecePosition, pair.newPiecePosition, promotedPieceType));
}
private void getPawnDiagonalAttack(List <Square> squares, Square square, Color pieceColor, int fileIndicator, int nextRank, List <AttackedSquare> attacks)
{
var pos = NotationEngine.CoordinatePairToPosition(fileIndicator, nextRank);
var attackedSquare = squares.GetSquare(pos);
if (attackedSquare.Occupied && attackedSquare.Piece.Color != pieceColor)
{
attacks.Add(new AttackedSquare(square, attackedSquare, false, true));
}
else
{
attacks.Add(new AttackedSquare(square, attackedSquare, false, true, true));
}
}
public OperationResult <StateInfo> GetStateInfo(GameState gameState, int piecePosition, int newPiecePosition)
{
var newActiveColor = gameState.ActiveColor.Reverse();
var stateInfo = new StateInfo();
var oldSquare = gameState.Squares.GetSquare(piecePosition);
var isValidCastleAttempt = this.IsValidCastleAttempt(gameState, oldSquare, newPiecePosition, gameState.Attacks);
if (isValidCastleAttempt.Success)
{
stateInfo.IsCastle = isValidCastleAttempt.Result;
}
else
{
return(OperationResult <StateInfo> .Fail(isValidCastleAttempt.Message));
}
stateInfo.IsPawnPromotion = this.isPawnPromotion(oldSquare, newPiecePosition);
if (gameState.EnPassantTargetSquare != "-" && oldSquare.Piece.PieceType == PieceType.Pawn)
{
var pawnEnPassantPosition = NotationEngine.CoordinateToPosition(gameState.EnPassantTargetSquare);
if (newPiecePosition == pawnEnPassantPosition)
{
stateInfo.IsEnPassant = true;
}
}
var isResign = false;
var isDraw = false;
// todo: i don't think we can get here
// also, this is incomplete
if (isDraw || isResign)
{
if (isDraw)
{
var score = string.Concat(" ", "1/2-1/2");
gameState.PGN += score;
}
if (isResign)
{
var score = string.Concat(" ", newActiveColor == Color.White ? "1-0" : "0-1");
gameState.PGN += score;
}
}
return(OperationResult <StateInfo> .Ok(stateInfo));
}
private string getEnPassantCoord(List <Square> squares, Color activeColor, int piecePosition, int newPiecePosition)
{
var piece = squares.GetPiece(newPiecePosition);
if (piece.PieceType != PieceType.Pawn)
{
return("-");
}
var diff = Math.Abs(piecePosition - newPiecePosition);
if (diff != 16)
{//16 is two rows
return("-");
}
var moveMarker = activeColor == Color.White ? 8 : -8;
var enPassantSquare = piecePosition + moveMarker;
return(NotationEngine.PositionToCoordinate(enPassantSquare));
}
private string getPGNMoveBeginState(char notationPiece, string coord, int startPos, int endPos, bool isCapture)
{
string pgnMove = string.Empty;
switch (notationPiece)
{
case 'P':
if (isCapture)
{
var file = NotationEngine.PositionToFileChar(startPos);
pgnMove = string.Concat(file, coord);
}
else
{
pgnMove = coord;
}
break;
case 'K':
var moveDiff = startPos - endPos;
switch (moveDiff)
{
case -2:
pgnMove = "O-O";
break;
case 2:
pgnMove = "O-O-O";
break;
default:
pgnMove = string.Concat(notationPiece, coord);
break;
}
break;
default:
pgnMove = string.Concat(notationPiece, coord);
break;
}
return(pgnMove);
}
private void getPawnAttacks(GameState gameState, Square square, List <AttackedSquare> accumulator)
{
var squares = gameState.Squares;
var position = square.Index;
var pieceColor = square.Piece.Color;
var coord = NotationEngine.PositionToCoordinate(position);
int file = NotationEngine.FileToInt(coord[0]);
int rank = NotationEngine.PositionToRankInt(position);
var directionIndicator = pieceColor == Color.White ? 1 : -1;
var homeRankIndicator = pieceColor == Color.White ? 2 : 7;
var nextRank = (rank + directionIndicator);
var aheadOneRankPosition = NotationEngine.CoordinatePairToPosition(file, nextRank);
var aheadOneRankSquare = squares.GetSquare(aheadOneRankPosition);
var attacks = new List <AttackedSquare>();
if (!aheadOneRankSquare.Occupied)
{
//can't attack going forward
attacks.Add(new AttackedSquare(square, aheadOneRankSquare, true));
}
managePawnAttacks(squares, square, pieceColor, file, rank, directionIndicator, homeRankIndicator, nextRank, attacks, aheadOneRankSquare.Occupied);
//add en passant position: -1 indicates null here
if (gameState.EnPassantTargetSquare != "-")
{
var enPassantTargetPosition = NotationEngine.CoordinateToPosition(gameState.EnPassantTargetSquare);
var leftPos = NotationEngine.CoordinatePairToPosition(file - 1, nextRank);
var rightPos = NotationEngine.CoordinatePairToPosition(file + 1, nextRank);
if (enPassantTargetPosition == leftPos || enPassantTargetPosition == rightPos)
{
var enPassantSquare = squares.GetSquare(enPassantTargetPosition);
attacks.Add(new AttackedSquare(square, enPassantSquare));
}
}
if (attacks.Any())
{
accumulator.AddRange(attacks);
}
}
public List <Square> GetSquares(Snapshot fen)
{
var squares = new List <Square>();
var rows = fen.PiecePlacement.Split('/');
for (int i = 0; i < 8; i++)
{
int rowIndex = 7 - i;
//leftSideIndex is the left side of the board, in numbers: 0 8 16 24 32 40 48 56
int leftSideIndex = 8 * (rowIndex);
int charIndex = 0;
var row = rows[i];
foreach (char c in row)
{
if (char.IsNumber(c))
{
int advanceSquare = 0;
Int32.TryParse(c.ToString(), out advanceSquare);
//gotta make empty squares
for (int j = 0; j < advanceSquare; j++)
{
var index = leftSideIndex + charIndex + j;
squares.Add(
new Square(index, NotationEngine.PositionToCoordinate(index), null)
);
}
//in FEN we move ahead the number of squares that the number says
charIndex = charIndex + advanceSquare;
}
else
{
var index = leftSideIndex + charIndex;
squares.Add(
new Square(index, NotationEngine.PositionToCoordinate(index), NotationEngine.GetPieceFromCharacter(c))
);
charIndex++;
}
}
}
return(squares.OrderBy(a => a.Index).ToList());
}
private void getKnightAttacks(GameState gameState, Square square, List <AttackedSquare> accumulator)
{
var squares = gameState.Squares;
var currentPosition = square.Index;
var pieceColor = square.Piece.Color;
var attacks = new List <AttackedSquare>();
var coord = NotationEngine.PositionToCoordinate(currentPosition);
var file = NotationEngine.FileToInt(coord[0]);
var rank = (int)coord[1];
var potentialPositions = new List <int> {
6, 10, 15, 17, -6, -10, -15, -17
};
foreach (var potentialPosition in potentialPositions)
{
var position = currentPosition + potentialPosition;
var _isValidKnightMove = isValidKnightMove(currentPosition, position, file, rank);
var _isValidMove = isValidMove(accumulator, gameState, square, position, pieceColor);
var _isValidCoordinate = GeneralEngine.IsValidCoordinate(position);
if (!_isValidKnightMove || !_isValidMove.IsValid || !_isValidCoordinate)
{
continue;
}
var attackedSquare = squares.GetSquare(position);
if (!attackedSquare.Occupied)
{
attacks.Add(new AttackedSquare(square, attackedSquare));
}
else
{
attacks.Add(new AttackedSquare(square, attackedSquare, isProtecting: attackedSquare.Piece.Color == pieceColor));
}
}
if (attacks.Any())
{
accumulator.AddRange(attacks);
}
}
public static Snapshot Create(string fen)
{
// 5 could be a bad number
if (fen.Length < 5 || !fen.Contains(' '))
{
return(null);
}
var fenRecord = new Snapshot();
var gameData = fen.Split(' ');
fenRecord.PiecePlacement = gameData[0];
fenRecord.ActiveColor = gameData[1][0] == 'w' ? Color.White : Color.Black;
fenRecord.CastlingAvailability = gameData[2];
fenRecord.EnPassantTargetSquare = gameData[3];
if (fenRecord.EnPassantTargetSquare != "-")
{
fenRecord.EnPassantTargetPosition = NotationEngine.CoordinateToPosition(fenRecord.EnPassantTargetSquare);
}
var enPassantTargetPosition = -1;
Int32.TryParse(gameData[3], out enPassantTargetPosition);
fenRecord.EnPassantTargetPosition = enPassantTargetPosition;
int halfmoveClock = 0;
Int32.TryParse(gameData[4], out halfmoveClock);
fenRecord.HalfmoveClock = halfmoveClock;
int fullmoveNumber = 0;
Int32.TryParse(gameData[5], out fullmoveNumber);
fenRecord.FullmoveNumber = fullmoveNumber;
return(fenRecord);
}
private void managePawnAttacks(List <Square> squares, Square square, Color pieceColor, int file, int rank, int directionIndicator, int homeRankIndicator, int nextRank, List <AttackedSquare> attacks, bool aheadOneRankSquareOccupied)
{
var notOnFarLeftFile = file - 1 >= 0;
var notOnFarRightFile = file + 1 <= 7;
if (notOnFarLeftFile)
{
//get attack square on left
var fileIndicator = file - 1;
getPawnDiagonalAttack(squares, square, pieceColor, fileIndicator, nextRank, attacks);
}
if (notOnFarRightFile)
{
//get attack square on right
var fileIndicator = file + 1;
getPawnDiagonalAttack(squares, square, pieceColor, fileIndicator, nextRank, attacks);
}
//can't move ahead two if the one in front of you is blocked.
if (aheadOneRankSquareOccupied)
{
return;
}
//have to plus one here because rank is zero based and coordinate is base 1
//if this pawn is on it's home rank, then add a second attack square.
var isOnHomeRank = rank + 1 == homeRankIndicator;
if (isOnHomeRank)
{
var forwardOne = nextRank + directionIndicator;
var rankForwardPosition = NotationEngine.CoordinatePairToPosition(file, forwardOne);
var rankForwardSquare = squares.GetSquare(rankForwardPosition);
//pawns don't attack forward, so we don't have attacks when people occupy ahead of us
if (!rankForwardSquare.Occupied)
{
attacks.Add(new AttackedSquare(square, rankForwardSquare, true));
}
}
}
private int getOrthogonalLineTerminator(Direction direction, int position)
{
var file = NotationEngine.PositionToFileInt(position);
var rank = NotationEngine.PositionToRankInt(position);
var iterator = getIteratorByDirectionEnum(direction);
switch (direction)
{
case Direction.Forward:
return(this.GetEntireFile(file).Max() + iterator);
case Direction.Backward:
return(this.GetEntireFile(file).Min() + iterator);
case Direction.Right:
return(this.GetEntireRank(rank).Max() + iterator);
case Direction.Left:
return(this.GetEntireRank(rank).Min() + iterator);
}
return(0);
}
//private List<int> getEntireDiagonalLine(int pos1, int pos2)
//{
// //diagonal moves: rise LtoR / or RtoL \
// var diff = Math.Abs(pos1 - pos2);
// var ltr = diff % 9 == 0;
// var rtl = diff % 7 == 0;
// if (!ltr && !rtl)
// {
// throw new Exception("What? This is supposed to be diagonal.");
// }
// var dxs = new List<int> { pos1, pos2 };
// //smallest # will be closest to the left or right in the line
// //the left terminating position is evenly divisible by 8
// //the right terminating position is evently divisible by 7
// //find terminators
// //left
// var increment = ltr ? 9 : 7;
// var smallest = dxs.Min();
// var largest = dxs.Max();
// var nextSmallest = smallest;
// while (nextSmallest % 8 > 0 && nextSmallest >= 0)
// {
// nextSmallest = nextSmallest - increment;
// if (nextSmallest >= 0 && !dxs.Contains(nextSmallest))
// {
// dxs.Add(nextSmallest);
// }
// };
// //right
// var nextLargest = largest;
// while (nextLargest % 7 > 0 && nextLargest <= 63)
// {
// nextLargest = nextLargest + increment;
// if (nextLargest <= 63 && !dxs.Contains(nextLargest))
// {
// dxs.Add(nextLargest);
// }
// };
// //fill in the middle
// var mid = smallest;
// var nextMid = mid;
// if (diff > increment)
// {
// while (nextMid < largest)
// {
// nextMid = nextMid + increment;
// if (!dxs.Contains(nextMid))
// {
// dxs.Add(nextMid);
// }
// }
// }
// return dxs;
//}
private List <int> getEntireOrthogonalLine(bool isRankMove, AttackedSquare x, bool trim = false)
{
List <int> result;
if (isRankMove)
{
var file = NotationEngine.PositionToFile(x.Index);
result = this._orthogonalService.GetEntireFile(file);
}
else
{
var rank = NotationEngine.PositionToRank(x.Index);
result = this._orthogonalService.GetEntireRank(rank);
}
if (!trim)
{
return(result);
}
var low = x.Index > x.AttackingSquare.Index ? x.AttackingSquare.Index : x.Index;
var high = x.Index < x.AttackingSquare.Index ? x.AttackingSquare.Index : x.Index;
return(result.Where(a => a > low && a < high).ToList());
}
// duplicated code?
//public bool IsDiagonalMove(int startPosition, int endPosition)
//{
// var startMod = startPosition % 8;
// var endMod = endPosition % 8;
// var modDiff = Math.Abs(startMod - endMod);
// var startRow = NotationUtility.PositionToRankInt(startPosition);
// var endRow = NotationUtility.PositionToRankInt(endPosition);
// var rowDiff = Math.Abs(startRow - endRow);
// if (modDiff == rowDiff)
// {
// return true;
// }
// return false;
//}
// var remainingKingAttacks = enemyKingAttacks.Except(opponentAttacks);
// if (remainingKingAttacks.Any()) {
// kingHasEscape = true;
// }
// if (kingHasEscape) {
// return false;
// }
// //make sure that interposition is not possible
// var attackers = opponentAttacks.Where(a => a.Index == enemyKingPosition.Index);
// //if there are no attackers there cannot be a single interposition that saves the king
// if (attackers == null || !attackers.Any() || attackers.Count() > 1) {
// return true;
// }
// var attacker = attackers.FirstOrDefault();
// var theAttack = this.AttackService.GetKingAttack(attacker, gameState, enemyKingPosition);
// var interposers = friendlyAttacks.ToList().Intersect(theAttack);
// if (interposers.Any()) {
// return false;
// }
// //there were no friendlies to save the king, checkmate is true
// return true;
//}
public bool IsEnPassant(Square square, int newPiecePosition, string enPassantTargetSquare)
{
if (enPassantTargetSquare == "-")
{
return(false);
}
var piece = square.Piece;
if (piece.PieceType != PieceType.Pawn)
{
return(false);
} //only pawns can perform en passant
var enPassantPosition = NotationEngine.CoordinateToPosition(enPassantTargetSquare);
if (enPassantPosition != newPiecePosition)
{
return(false);
} //if we're not moving to the en passant position, this is not en passant
var moveDistance = Math.Abs(square.Index - newPiecePosition);
if (!new List <int> {
7, 9
}.Contains(moveDistance))
{
return(false);
} //is this a diagonal move?
if (piece.Color == Color.Black && square.Index < newPiecePosition)
{
return(false);
} //black can't move up
if (piece.Color == Color.White && square.Index > newPiecePosition)
{
return(false);
} //white can't move down
return(true);
}
private string getPgnMove(char notationPiece, Piece piece, string coord, int startPos, int endPos, bool isCapture, GameState gameState)
{
var captureMarker = isCapture ? "x" : string.Empty;
var pgnMove = getPGNMoveBeginState(notationPiece, coord, startPos, endPos, isCapture);
var result = string.Empty;
// figure out if additional information needs to be placed on the pgn move
// this should only need to happen if the pieces are of the same type
var movingSquare = gameState.Squares.Where(a => a.Index == startPos).First();
var otherSquaresOfThisTypeWithThisAttack = from s in gameState.Attacks
where s.Index == endPos &&
s.AttackingSquare.Index != movingSquare.Index &&
s.AttackingSquare.Piece.PieceType == movingSquare.Piece.PieceType &&
s.AttackingSquare.Piece.Color == gameState.ActiveColor
select s;
if (otherSquaresOfThisTypeWithThisAttack.Count() <= 0)
{
return(string.Concat(pgnMove.Substring(0, 1), captureMarker, pgnMove.Substring(1, pgnMove.Length - 1)));
}
var secondPiece = otherSquaresOfThisTypeWithThisAttack.First();
if (secondPiece.AttackingSquare.Piece.PieceType == PieceType.Pawn && !isCapture)
{
result = string.Concat(pgnMove.Substring(0, 1), captureMarker, pgnMove.Substring(1, pgnMove.Length - 1));
return(result);
}
// if other piece is on same the file of departure (if they differ); or
var movingPieceFile = NotationEngine.PositionToFileChar(startPos);
var otherPieceFile = NotationEngine.PositionToFileChar(secondPiece.Index);
if (movingPieceFile != otherPieceFile)
{
if (notationPiece == 'P')
{
result = string.Concat(movingPieceFile, captureMarker, pgnMove);
}
else
{
result = string.Concat(pgnMove.Substring(0, 1), movingPieceFile, captureMarker, pgnMove.Substring(1, pgnMove.Length - 1));
}
return(result);
}
else
{
// the rank of departure (if the files are the same but the ranks differ)
// these are index = 0 rank/file, so add one for PGN output
var movingPieceRank = NotationEngine.PositionToRankInt(startPos) + 1;
var otherPieceRank = NotationEngine.PositionToRankInt(secondPiece.Index) + 1;
if (movingPieceRank != otherPieceRank)
{
result = string.Concat(pgnMove.Substring(0, 1), movingPieceRank, captureMarker, pgnMove.Substring(1, pgnMove.Length - 1));
return(result);
}
else
{
// both the rank and file
// (if neither alone is sufficient to identify the piece—which occurs only in rare cases where one or more pawns have promoted,
// resulting in a player having three or more identical pieces able to reach the same square).
result = string.Concat(pgnMove.Substring(0, 1), movingPieceFile, movingPieceRank, captureMarker, pgnMove.Substring(1, 2));
return(result);
}
}
}
public Square GetCurrentPositionFromPGNMove(GameState gameState, Piece piece, int newPiecePosition, string pgnMove, bool isCastle)
{
if (isCastle)
{
return(getOriginationPositionForCastling(gameState, piece.Color));
}
// adding !a.MayOnlyMoveHereIfOccupiedByEnemy fixed the test I was working on, but there may be a deeper issue here.
var potentialSquares = gameState.Attacks.Where(a =>
a.Index == newPiecePosition &&
(
a.Occupied || (!a.Occupied && !a.MayOnlyMoveHereIfOccupiedByEnemy)
) &&
a.AttackingSquare.Piece.PieceType == piece.PieceType &&
a.AttackingSquare.Piece.Color == piece.Color
);
if (!potentialSquares.Any())
{
// this could be a pawn en passant
if (
piece.PieceType == PieceType.Pawn &&
gameState.EnPassantTargetSquare != "-" &&
NotationEngine.CoordinateToPosition(gameState.EnPassantTargetSquare) == newPiecePosition
)
{
var enPassant = gameState.Attacks.Where(a =>
a.Index == newPiecePosition &&
a.AttackingSquare.Piece.PieceType == piece.PieceType &&
a.AttackingSquare.Piece.Color == piece.Color
).First().AttackingSquare;
return(enPassant);
}
var msg = $"No squares found. PGN Move: { pgnMove }";
throw new Exception(msg);
}
if (potentialSquares.Count() == 1)
{
return(potentialSquares.First().AttackingSquare);
}
// differentiate
var potentialPositions = from s in gameState.Squares
join p in potentialSquares on s.Index equals p.AttackingSquare.Index
where s.Piece.Identity == piece.Identity
select p;
if (!potentialPositions.Any())
{
var msg = $"Attempting to differentiate. No squares found. PGN Move: { pgnMove }";
throw new Exception(msg);
}
// x means capture and shouldn't be used in the equation below
var capture = isCapture(pgnMove);
var check = isCheck(pgnMove);
// todo: refactor to eliminate redundancy
// look at the beginning of the pgnMove string to determine which of the pieces are the one that should be moved.
// this should only happen if there are two pieces of the same type that can attack here.
var newPgnMove = pgnMove.Replace("x", "").Replace("+", "");
var moveLength = newPgnMove.Length;
switch (moveLength)
{
case 2:
return(pgnLength2(piece, potentialPositions, capture));
case 3:
// this should be a pawn attack that can be made by two pawns
// this can also be a pawn promotion
return(pgnLength3(potentialPositions, newPgnMove));
case 4: // this would be any other piece
return(pgnLength4(gameState, potentialPositions, newPgnMove));
case 5: // we have rank and file, so just find the piece. this should be very rare
return(pgnLength5(gameState, newPgnMove));
default:
throw new Exception("Failed to find square.");
}
}