/// <summary>
/// Reverts last move applied to the board
/// </summary>
public void RevertLastMove()
{
MoveInformation lastMove = Moves.Last();
Moves.RemoveAt(Moves.Count() - 1);
ChessPiece lastPieceMoved = FindPieceAt(lastMove.End.File, lastMove.End.Rank);
lastPieceMoved.Move(lastMove.Start.File, lastMove.Start.Rank);
if (lastMove.FirstMove)
{
lastPieceMoved.Deployed = false; // Reset first move
}
// Undo captures
lastMoveWasCapture = false;
if (lastMove.IsCapture)
{
lastMove.CapturedPiece.Captured = false;
lastMoveWasCapture = true;
}
if (lastMove.IsPromotion)
{
lastPieceMoved.Demote();
}
// Undo a castling move
if (lastMove.IsCastle)
{
// Move the rook back as well
ChessPiece rook = lastMove.CastlingRook;
PieceFile castleTargetFile = lastMove.End.File;
int rookRank = (rook.Color == PieceColor.White) ? 1 : 8;
if (castleTargetFile.ToInt() == 7) // g->h
{
rook.Move(new PieceFile('h'), rookRank);
}
else if (castleTargetFile.ToInt() == 3) // c->a
{
rook.Move(new PieceFile('a'), rookRank);
}
else
{
// It has to be one of the above if logic is correct
throw new IndexOutOfRangeException();
}
rook.Deployed = false;
}
// Reset castling rights
ActivePlayerCastlingRights = lastMove.CastlingRights;
// Flip players
activePlayer = OppositeColor(activePlayer);
// Set last FEN
currentFEN = lastMove.PreviousFEN;
}
/// <summary>
/// Find the rect for a given location on the board
/// </summary>
/// <param name="file">File for the piece</param>
/// <param name="rank">Rank for the piece</param>
/// <returns>Rectangle for the board location in client coordinates</returns>
private Rectangle GetRect(PieceFile file, int rank)
{
// This simple diagram helps demonstrate the inverted relationship
// (not pictured is the overall board offset)
//
// Black White
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 8 | |X| |X| |X| |X| | |X| |X| |X| |X| 1
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 7 |X| |X| |X| |X| | |X| |X| |X| |X| | 2
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 6 | |X| |X| |X| |X| | |X| |X| |X| |X| 3
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 5 |X| |X| |X| |X| | |X| |X| |X| |X| | 4
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 4 | |X| |X| |X| |X| | |X| |X| |X| |X| 5
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 3 |X| |X| |X| |X| | |X| |X| |X| |X| | 6
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 2 | |X| |X| |X| |X| | |X| |X| |X| |X| 7
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// 1 |X| |X| |X| |X| | |X| |X| |X| |X| | 8
// +-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
// a b c d e f g h h g f e d c b a
// White Black
int X;
int Y;
// PieceFile is 1-based, same as the physical board
if (data.Orientation == BoardOrientation.WhiteOnBottom)
{
X = (file.ToInt() - 1) * squareSizeInPixels;
Y = (8 - rank) * squareSizeInPixels;
}
else
{
X = (8 - file.ToInt()) * squareSizeInPixels;
Y = (rank - 1) * squareSizeInPixels;
}
// Return the calculated rect offset from the overall topLeft location
return(new Rectangle(X + topLeft.X, Y + topLeft.Y, squareSizeInPixels, squareSizeInPixels));
}
/// <summary>
/// Returns true if the current piece is trying to castle. It must be
/// a king that moved in the correct manner (2 squares horizontally)
/// </summary>
/// <param name="piece">ChessPiece to check</param>
/// <param name="targetFile">ChessFile the piece is moving to</param>
/// <returns>True if the move is a castling move</returns>
private bool IsCastling(ChessPiece piece, PieceFile targetFile)
{
bool result = false;
int deltaSquares = Math.Abs(piece.File.ToInt() - targetFile.ToInt());
if ((piece.Job == PieceClass.King) && (deltaSquares == 2))
{
result = true;
}
return(result);
}
/// <summary>
/// Checks if a given piece can target a specified square. It is not required
/// that the square be occupied by an enemy piece, just potentially reachable
/// </summary>
/// <param name="board">ChessBoard to check against</param>
/// <param name="piece">ChessPiece to check</param>
/// <param name="targetFile">file to target</param>
/// <param name="targetRank">rank to target</param>
/// <returns>true if the piece can target the given square</returns>
public static bool CanPieceTargetSquare(ChessBoard board, ChessPiece piece, PieceFile targetFile, int targetRank)
{
bool result = false;
if (piece.Captured == true)
{
return(false);
}
BoardSquare targetSquare = new BoardSquare(targetFile, targetRank);
List <BoardSquare> moves = new List <BoardSquare>();
switch (piece.Job)
{
case PieceClass.Pawn:
// Can't reuse the normal helper as it requires the space to be occupied
// also w/o en-passant and double moves, this can be simpler
int pawnTargetRank = (piece.Color == PieceColor.White) ? piece.Rank + 1 : piece.Rank - 1;
if (targetRank == pawnTargetRank)
{
if (((piece.File.ToInt() - 1) == targetFile.ToInt()) ||
((piece.File.ToInt() + 1) == targetFile.ToInt()))
{
result = true;
}
}
break;
case PieceClass.Knight:
moves = GetLegalMoves_Knight(piece, board);
break;
case PieceClass.Bishop:
moves = GetLegalMoves_Bishop(piece, board);
break;
case PieceClass.Rook:
moves = GetLegalMoves_Rook(piece, board);
break;
case PieceClass.Queen:
moves = GetLegalMoves_Queen(piece, board);
break;
case PieceClass.King:
// don't recurse into the normal call, also alternate method to examine
// These are pairs of offsets (-1, 0), (-1, 1),...etc so there are twice
// as many of these as squares to check
int[] offsets = new int[] { -1, 0, -1, 1, -1, -1, 1, 0, 1, 1, 1, -1, 0, 1, 0, -1 };
for (int index = 0; index < offsets.Length / 2; index++)
{
int fileOffset = offsets[index * 2];
int rankOffset = offsets[(index * 2) + 1];
// Test the validity of the square offset
if (BoardSquare.IsValid(piece.File.ToInt() + fileOffset, piece.Rank + rankOffset))
{
BoardSquare testSquare =
new BoardSquare(new PieceFile(piece.File.ToInt() + fileOffset), piece.Rank + rankOffset);
if (testSquare == targetSquare)
{
result = true;
break;
}
}
}
break;
default:
throw new ArgumentOutOfRangeException();
}
// King is special above
if (piece.Job != PieceClass.King)
{
// Check moves for the target square
foreach (BoardSquare square in moves)
{
if (square == targetSquare)
{
result = true;
break;
}
}
}
return(result);
}
