public ChessMove(BoardSquare start, BoardSquare end, char pieceMoved, bool isCapture, Piece promotedPiece)
{
this.startSquare = start;
this.endSquare = end;
this.pieceMoved = pieceMoved;
this.checkIndicator = '\0';
this.isCapture = isCapture;
if (promotedPiece != null)
this.promotedPiece = promotedPiece.Notational;
// Determine if the move resulted in castling
if (this.pieceMoved == (char)Piece.PieceNotation.King && start.X - end.X == 2)
this.castleNotation = CASTLE_QUEEN;
else if (this.pieceMoved == (char)Piece.PieceNotation.King && start.X - end.X == -2)
this.castleNotation = CASTLE_KING;
else
this.castleNotation = String.Empty;
}
public bool IsBetweenPoints(BoardSquare endPointA, BoardSquare endPointB)
{
BoardSquare maxVals = BoardSquare.Empty, minVals = BoardSquare.Empty;
maxVals.X = Math.Max(endPointA.X, endPointB.X);
maxVals.Y = Math.Max(endPointA.Y, endPointB.Y);
minVals.X = Math.Min(endPointA.X, endPointB.X);
minVals.Y = Math.Min(endPointA.Y, endPointB.Y);
/*if (endPointA.X > endPointB.X)
{
maxVals.X = endPointA.X;
minVals.X = endPointB.X;
}
else
{
minVals.X = endPointA.X;
maxVals.X = endPointB.X;
}
if (endPointA.Y > endPointB.Y)
{
maxVals.Y = endPointA.Y;
minVals.Y = endPointB.Y;
}
else
{
minVals.Y = endPointA.Y;
maxVals.Y = endPointB.Y;
}*/
if (this.X < minVals.X || this.X > maxVals.X || this.Y < minVals.Y || this.Y > maxVals.Y)
return false;
// Avoid divide by zero, the line goes straight up
if (endPointB.X == endPointA.X)
{
return endPointB.X == endPointB.X;
}
else
{
double slope = (endPointB.Y - endPointA.Y) / (endPointB.X - endPointA.X);
// The line is not a clear diagonal or straight across
if (slope != 0 && Math.Abs(slope) != 1)
return false;
else
{
double yInt = endPointB.Y - slope * endPointB.X;
return (this.Y == slope * this.X + yInt);
}
}
}
/*
* Determines if the last move caused the game to end
*
* First, check if the king is in check, and store it in a boolean variable.
*
* If the king is in check, check if the attack is preventable. This is done
* by seeing it the king can either move away safely or can neutralize all
* attacks (both the primary attack and discoveryCheck if it occured). If the
* king is in check and the conditions checking if the attempted capture
* is preventable, checkmate has occured, otherwise the game is not over and the
* King is simply in check.
*
* If the king is not in check, determine if any of the various draw conditions are
* met, including by repetition, redundancy (x moves without a capture or pawn movement),
* stalemate (where a player can not make a legal move) and by material (where neither side
* has enough material to checkmate).
*
* If none of those conditions are met, the game can still be played, and is
* considered to have normal status.
*/
private void IsGameOver(ChessMove.MoveStatusCodes moveType, BoardSquare directAttacker)
{
// Check if king is in check (discovered, normal)
// Be sure to account for rook when castled, removed pawn in en passant
// If one or the other, check for blocks, capture, move out of way
// If both, check move out of way
// If neither, check other pieces can move (stalemate)
// Check draw by repetition, inaction (no capture/movement), and material
// Set gameStatus internal variable as appropriate
BoardSquare currKingPos = this.kingPos[(int)(whiteTurn ? Sides.white : Sides.black)];
BitBoard futureMoves = this.board[directAttacker].getAllMoves(this.board, (short)directAttacker.X, (short)directAttacker.Y);
bool isDirectCheck = futureMoves.Contains(currKingPos);
bool isDiscoverCheck;
this.attackingPieces[(int)AttackTypes.discovery] = ExtrapolateAttack((short)this.startCoord.X, (short)this.startCoord.Y, (short)currKingPos.X, (short)currKingPos.Y);
this.attackingPieces[(int)AttackTypes.regular] = isDirectCheck ? endCoord : BoardSquare.Empty;
isDiscoverCheck = this.attackingPieces[(int)AttackTypes.discovery] != BoardSquare.Empty;
if (!isDiscoverCheck)
{
BoardSquare lastKingPos = this.kingPos[(int)(whiteTurn ? Sides.black : Sides.white)];
if (moveType == ChessMove.MoveStatusCodes.queenCastle)
{
isDiscoverCheck = this[lastKingPos.Y, lastKingPos.X + 1].getAllMoves(this.board, (short)(this.endCoord.X + 1), (short)this.endCoord.Y).Contains(currKingPos);
if (isDiscoverCheck)
this.attackingPieces[(int)AttackTypes.discovery] = new BoardSquare(lastKingPos.X + 1, lastKingPos.Y);
}
else if (moveType == ChessMove.MoveStatusCodes.queenCastle)
{
isDiscoverCheck = this[lastKingPos.Y, lastKingPos.X - 1].getAllMoves(this.board, (short)(this.endCoord.X - 1), (short)this.endCoord.Y).Contains(currKingPos);
if (isDiscoverCheck)
this.attackingPieces[(int)AttackTypes.discovery] = new BoardSquare(lastKingPos.X - 1, lastKingPos.Y);
}
else if (moveType == ChessMove.MoveStatusCodes.enPassant)
{
// Check captured square
this.attackingPieces[(int)AttackTypes.discovery] = ExtrapolateAttack((short)endCoord.X, (short)startCoord.Y, (short)currKingPos.X, (short)currKingPos.Y);
isDiscoverCheck = this.attackingPieces[(int)AttackTypes.discovery] != BoardSquare.Empty;
}
}
if (isDirectCheck || isDiscoverCheck)
{
this.gameStatus = GameStatusCodes.check;
// If king can't move safely, check alternatives
if (this.board[currKingPos].getAllMoves(this.board, (short)currKingPos.X, (short)currKingPos.Y) == BitBoard.Empty)
{
// Double attack, can only get out of it by moving
if (isDirectCheck && isDiscoverCheck)
this.gameStatus = GameStatusCodes.checkMate;
else
{
BoardSquare attackSquare = BoardSquare.Empty;
bool canBlockCap = false;
if (isDirectCheck) attackSquare = this.attackingPieces[(int)AttackTypes.regular];
else attackSquare = this.attackingPieces[(int)AttackTypes.discovery];
// Check for blocking, capture
foreach (BoardSquare sq in this.board)
{
Piece p = this.board[sq];
if (p.Colour == this.board[currKingPos].Colour)
{
BitBoard bbMoves = p.getAllMoves(this.board, (short)sq.X, (short)sq.Y);
foreach (BoardSquare sqMove in bbMoves)
{
// Can block or capture
if (sqMove == attackSquare || (!(board[sq] is King) && sqMove.IsBetweenPoints(currKingPos, attackSquare))
|| board[sq] is Pawn && ((Pawn)board[sq]).MayEnPassant(this.board, (short)sq.X, (short)sq.Y, (short)sqMove.X, (short)sqMove.Y))
{
canBlockCap = true;
break;
}
}
if (canBlockCap)
break;
}
}
if (!canBlockCap)
this.gameStatus = GameStatusCodes.checkMate;
}
}
}
else
{
gameStatus = GameStatusCodes.normal;
//Check for draw conditions (stalemate, repetition, inactivity (no capture/pawn), material
if (this.positions.isDrawByMoves())
this.gameStatus = GameStatusCodes.forcedDraw;
else if (this.lastMove.IsCapture && IsDrawByMaterial())
this.gameStatus = GameStatusCodes.drawByMaterial;
else
{
bool isStalemate = true;
char nextMoveCol = whiteTurn ? Piece.NOTATION_W : Piece.NOTATION_B;
foreach (BoardSquare sq in this.board)
if (this.board[sq].Colour == nextMoveCol && this.board[sq].getAllMoves(this.board, (short)sq.X, (short)sq.Y) != BitBoard.Empty)
{
isStalemate = false;
break;
}
if (isStalemate)
this.gameStatus = GameStatusCodes.stalemate;
}
}
}
/*
* Standard set of actions that occur when a valid turn takes takes place.
*
* The two arguments, currPos and newPos, are character representations
* of the original and new positions of the moved piece respectively
*
* First, the board array is updated.
* Second, switch internal track of move, and record the last move.
* Third, update the array of repeatable board positions, clear discoverCheckPiece, and increment the move count for draws
* Fourth of all, if the piece that moved was the king, update his board position in the array
* Lastly, check to see if this move causes the game to end
*/
private void DoTurn(ChessMove.MoveStatusCodes moveType)
{
BoardSquare directAttacker = endCoord;
switch (moveType)
{
case ChessMove.MoveStatusCodes.enPassant:
board[lastMove.EndSquare.Y, lastMove.EndSquare.X] = null;
break;
case ChessMove.MoveStatusCodes.kingCastle:
board.movePiece(Board.NUM_FILES-1, startCoord.Y, startCoord.X + 1, startCoord.Y);
directAttacker = new BoardSquare(startCoord.X + 1, startCoord.Y);
break;
case ChessMove.MoveStatusCodes.queenCastle:
board.movePiece(0, startCoord.Y, startCoord.X - 1, startCoord.Y);
directAttacker = new BoardSquare(startCoord.X - 1, startCoord.Y);
break;
}
// Update internal board position and move trackers
lastMove = new ChessMove(startCoord, endCoord, board[startCoord].Notational, board[endCoord] != null);
allMoves.Add(lastMove);
board.movePiece(startCoord.X, startCoord.Y, endCoord.X, endCoord.Y);
// Switch who's move it is and record move
whiteTurn = !whiteTurn;
// Update internal move-by-move trackers
positions.add(lastMove, board);
// Update position of king if king moved
if (lastMove.PieceMoved == (char)Piece.PieceNotation.King)
{
kingPos[Convert.ToInt32(whiteTurn)] = endCoord;
((King)board[endCoord]).HasNotMoved = false;
}
if (moveType != ChessMove.MoveStatusCodes.pawnPromote)
IsGameOver(moveType, directAttacker);
}
public void SetPromotedValue(BoardSquare square, Piece newPiece)
{
if (square.Y == (whiteTurn ? 0 : Board.NUM_ROWS - 1))
{
Piece endSquare = board[square];
if (endSquare != null && endSquare is Pawn)
{
board[square] = newPiece;
IsGameOver(ChessMove.MoveStatusCodes.pawnPromote, this.endCoord);
}
}
}
/*
* Based on the current position and attempted new position of a piece, determines if the move
* is valid. Owing to View-Layer checking, it is known that the starting coordinate holds a piece
* pf the colour who's turn it is to move, and the ending coordinate does not hold a piece of the
* same colour.
*
* Checking starts off by taking the two board coordinates, passed in as 2 character arrays, and
* converting them to integers so they can be accurately used to reference the 2-D board array
* holding all the pieces.
*
* First to be checked is if performing the move would leave the player in check. Since a cardinal
* rule of chess involves not ending your turn while you yourself are in check, if true is returned by
* this function, it is an invalid move, all other checking is ignored, and the appropriate flag is
* returned.
*
* Next check to see if the move is a traditional movement of a piece by checking if the square it's moving
* to is unoccupied, if the movement follows that piece's traditional movement pattern, and that no pieces
* lie in the way of the movement. If it is, it is a valid movement, and some piece-specific checking occurs.
* If it was a king , indicate that he has moved (meaning that he can no longer castle). If it was a pawn, reset
* the draw counters for draw by repetition and movement, and check and see if the pawn has reached the far side
* of the board. If it did, perform the turn and return the appropriate flag. If not, piece specific checking
* ends, the turn is performed, and the movement is a typical movement.
*
* If the movement is not a typical movement, checking occurs to see if it is a traditional capture. This means
* that the square the piece is moving to is occupied, the movement follows the piece's traditional capture
* movement pattern, and that there are no pieces in the way. If it is, the same actions occur here as do if
* a regular movement has occured, with the exception that the draw counters are always reset, instead of just
* if a pawn was moved.
*
* If none of the above conditions are met, exception checking occurs.
* First, if the piece moved was a pawn, checking for en Passant is dealt with. If the movement was valid as
* being en Passant, reset the draw counters, set the square contents of the captured piece to null manually
* (since the square was never clicked on, doTurn can not handle doing that), perform the turn, and return
* the appropriate flag.
* Second, checking for castling occurs, by seeing if the square moved to is null and castling is allowed for
* that piece. If it is, the current rank and file of the involved rook is calculated, as is the ending
* X-coordinate of the rook. Then it is tested if the involved rook is actually on the square that it
* needs to be on, that there is nothing in between the rook and king, and that the square the
* king is moving over on it's way to it's ending position is not under attack. If all of these conditions
* are met, it is a valid castling, the turn is performed, and the appropriate value is returned.
*
* If none of the conditions are met, it is an invalid move, and a flag is returned indicating this.
*/
public ChessMove.MoveStatusCodes IsValidTurn(char[] currPos, char[] newPos)
{
startCoord = new BoardSquare(currPos[0], currPos[1]);
endCoord = new BoardSquare(newPos[0], newPos[1]);
Piece startPiece = board[startCoord];
Piece endPiece = board[endCoord];
ChessMove.MoveStatusCodes resultant = ChessMove.MoveStatusCodes.invalidMove;
// Clicked on own piece, nothing in way of desired move
if (startPiece != null && startPiece.Colour == (whiteTurn ? Piece.NOTATION_W : Piece.NOTATION_B) && (endPiece == null || endPiece.Colour != startPiece.Colour) /* && IsPieceFreeToMove((short)startCoord.X, (short)startCoord.Y, (short)endCoord.X, (short)endCoord.Y) */)
{
BitBoard b = startPiece.getAllMoves(this.board, (short)startCoord.X, (short)startCoord.Y);
if (b.Contains(endCoord))
{
resultant = ChessMove.MoveStatusCodes.normalMovement;
if (startPiece is King)
{
if (startCoord.X - endCoord.X == -2)
resultant = ChessMove.MoveStatusCodes.kingCastle;
else if (startCoord.X - endCoord.X == 2)
resultant = ChessMove.MoveStatusCodes.queenCastle;
}
else if (startPiece is Pawn)
{
if (endCoord.Y == ((Pawn)startPiece).GetLastRow())
resultant = ChessMove.MoveStatusCodes.pawnPromote;
else if (endCoord.X - startCoord.X != 0 && this[endCoord.Y, endCoord.X] == null)
resultant = ChessMove.MoveStatusCodes.enPassant;
}
DoTurn(resultant);
}
}
return resultant;
}
public ChessMove(BoardSquare start, BoardSquare end, char pieceMoved, bool isCapture)
: this(start, end, pieceMoved, isCapture, null)
{
}