/// <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>
/// Invoked when the chess engine has responded with a move to apply to the
/// local board
/// </summary>
private void OnEngineBestMoveResponse()
{
thinkingIndex = 0; // reset index counter for simple progress text
// Get the best move from the engine
string bestMove = engine.BestMove;
if ((String.Compare(bestMove, "(none)") == 0) || // Stockfish (and converted ones)
(String.Compare(bestMove, "a1a1") == 0) || // Rybka
(board.HalfMoveCount >= HalfMovesUntilDraw)) // Propably spinning on self play or just a draw
{
if (board.HalfMoveCount >= HalfMovesUntilDraw)
{
Debug.WriteLine("Draw by 50 moves rule...");
}
GameOverHandler();
}
else if (GetInputState() == InputState.WaitingOnOpponentMove)
{
// Extract the board location from the move string
PieceFile startFile = new PieceFile(bestMove[0]);
int startRank = Convert.ToInt16(bestMove[1]) - Convert.ToInt16('0');
PieceFile destFile = new PieceFile(bestMove[2]);
int destRank = Convert.ToInt16(bestMove[3]) - Convert.ToInt16('0');
ChessPiece foundPiece = board.FindPieceAt(startFile, startRank);
MoveInformation moveInfo = new MoveInformation(
new BoardSquare(startFile, startRank),
new BoardSquare(destFile, destRank),
foundPiece.Deployed, board.CurrentFEN);
moveInfo.Color = foundPiece.Color;
moveInfo.CastlingRights = board.ActivePlayerCastlingRights;
// When coming from the engine, we get the promotion detection for free
if (bestMove.Length == 5)
{
// Applied on the next move
PieceClass promotionJob = ChessBoard.PieceClassFromFen(bestMove[4]);
board.PromotePiece(startFile, startRank, destFile, destRank, promotionJob, ref moveInfo);
}
// Move the piece on the board, and add it to the official moves list
board.MovePiece(ref moveInfo);
// trigger a redraw
view.Invalidate();
// Apply the move the engine just gave us with the engine (update it's own move)
UpdateEnginePosition();
}
}
/// <summary>
/// Process the input when waiting for the current player to select a move
/// </summary>
/// <param name="x">x coordinate in form</param>
/// <param name="y">y coordinate in form</param>
private void OnWaitingForMoveSelection(int x, int y)
{
BoardSquare square = ((IChessBoardView)view).GetSquare(x, y);
foreach (BoardSquare move in legalMoves)
{
if (move == square)
{
// Done - this is the move
MoveInformation moveInfo = new MoveInformation(
new BoardSquare(selectedPiece.File, selectedPiece.Rank), move, selectedPiece.Deployed, board.CurrentFEN);
moveInfo.Color = selectedPiece.Color;
moveInfo.CastlingRights = board.ActivePlayerCastlingRights;
Debug.WriteLine("Valid Move Detected: [{0},{1}]=>[{2},{3}]",
selectedPiece.File, selectedPiece.Rank, move.File, move.Rank);
// Need to detect promotion and launch dialog for it...
bool isPawnMovingToBackRank = (selectedPiece.Color == PieceColor.White) ? (moveInfo.End.Rank == 8) : (moveInfo.End.Rank == 1);
if ((selectedPiece.Job == PieceClass.Pawn) && isPawnMovingToBackRank)
{
PieceClass promotionJob = view.ChoosePromotionJob();
board.PromotePiece(moveInfo.Start.File, moveInfo.Start.Rank, moveInfo.End.File, moveInfo.End.Rank, promotionJob, ref moveInfo);
}
// Always returns true now
board.MovePiece(ref moveInfo);
view.Invalidate();
Debug.WriteLine(String.Format("Fullmoves: {0}", board.FullMoveCount));
Debug.WriteLine(String.Format("Halfmoves: {0}", board.HalfMoveCount));
Debug.WriteLine(String.Format("WhCastle: {0}", board.WhiteCastlingRights.ToString()));
Debug.WriteLine(String.Format("BlCastle: {0}", board.BlackCastlingRights.ToString()));
// Update the position with the engine
UpdateEnginePosition();
break;
}
}
// Either way this gets cleared
legalMoves.Clear();
((IChessBoardView)view).ClearHiglightedSquares();
selectedPiece = null;
}
/// <summary>
/// Moves the rook for a castle move of a King. At this point the castling
/// has (or should have) been detected. This is called to bring the rook
/// along for the ride when the king is moved. See IsCastling for detection
/// </summary>
/// <param name="targetFile">ChessFile the King is moving to</param>
/// <param name="moveInfo">Extended move information</param>
private void PerformCastle(PieceFile targetFile, ref MoveInformation moveInfo)
{
// Find the corresponding Rook and move it too
int rookRank = (activePlayer == PieceColor.White) ? 1 : 8;
PieceFile gTargetFile = new PieceFile('g');
PieceFile cTargetFile = new PieceFile('c');
PieceFile rookStartFile;
PieceFile rookTargetFile;
// These are the only 2 legal files to move a king when castling
// and they are the same for both players (only the rank differs above)
if (targetFile == gTargetFile)
{
rookStartFile = new PieceFile('h');
rookTargetFile = new PieceFile('f');
}
else if (targetFile == cTargetFile)
{
rookStartFile = new PieceFile('a');
rookTargetFile = new PieceFile('d');
}
else
{
// If the above chess logic was sound, this should not happen.
throw new ArgumentOutOfRangeException();
}
// Get the rook (which should exist if logic is sound)
ChessPiece castleRook = FindPieceAt(rookStartFile, rookRank);
// Move it
castleRook.Move(rookTargetFile, rookRank);
// Save the castling info
moveInfo.CastlingRook = castleRook;
// Remove all castling rights for the active player
if (activePlayer == PieceColor.White)
{
whiteCastlingRights = BoardSide.None;
}
else
{
blackCastlingRights = BoardSide.None;
}
}
/// <summary>
/// When a pawn has made it to the back rank, it can be promoted. This method
/// will mark a piece as needing promotion on the next move. We don't want to
/// change the job until it has moved to keep inline with the rest of the logic
/// </summary>
/// <param name="startFile"></param>
/// <param name="startRank"></param>
/// <param name="targetFile"></param>
/// <param name="targetRank"></param>
/// <param name="promotionClass"></param>
/// <param name="moveInfo">Detailed move info</param>
public void PromotePiece(PieceFile startFile, int startRank, PieceFile targetFile, int targetRank, PieceClass promotionClass, ref MoveInformation moveInfo)
{
ChessPiece piece = FindPieceAt(startFile, startRank);
int validRank = (piece.Color == PieceColor.White) ? 8 : 1;
if (targetRank != validRank)
{
throw new ArgumentOutOfRangeException();
}
// Find the pawn and mark it
if (piece.Job != PieceClass.Pawn)
{
// Logic check
throw new InvalidOperationException();
}
moveInfo.PromotionJob = promotionClass;
piece.PromoteOnNextMove(promotionClass);
}
/// <summary>
/// Move a piece from startFile:startRank -> targetFile:targetRank. Because
/// self-play is the only mode enabled right now, these moves are always
/// going to be considered valid, since they came from the chess engine
/// (and we will assume it is correct). In the future, this will likely
/// remain, and validation of the legallity for the player can be handled
/// above this call
/// </summary>
/// <param name="moveInfo">detailed move information struct</param>
public void MovePiece(ref MoveInformation moveInfo)
{
// Get the player piece at the starting location
// Piece should never be null if chess logic is sound
PieceFile startFile = moveInfo.Start.File;
int startRank = moveInfo.Start.Rank;
PieceFile targetFile = moveInfo.End.File;
int targetRank = moveInfo.End.Rank;
ChessPiece playerPiece = FindPieceAt(startFile, startRank);
if (playerPiece.Color != activePlayer)
{
// This also should not be able to happen with correct game logic
throw new InvalidOperationException();
}
// Get each side's pieces
List <ChessPiece> playerPieces = ActivePlayerPieces;
List <ChessPiece> opponentPieces = OpponentPlayerPieces;
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// PRE-MOVE CHECKS
// We have to detect castling. It does not come across the wire as O-O or O-O-O
// but rather as a regular move like e1g1. Separate the detection from the move
// of the rook
bool isCastling = IsCastling(playerPiece, targetFile);
// We also need to check for an en-passant capture if the pieces is a pawn
if (playerPiece.Job == PieceClass.Pawn)
{
moveInfo.CapturedPiece = HandleEnPassant(startFile, startRank, targetFile, targetRank);
}
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// RAW MOVE(S)
playerPiece.Move(targetFile, targetRank);
if (isCastling)
{
PerformCastle(targetFile, ref moveInfo); // Also move the rook if needed
}
// ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
// POST-MOVE CHECKS/UPDATES
// For normal captures, just do a quick iteration of the opponent pieces
// there are only 16 of these total in normal chess
foreach (ChessPiece enemyPiece in opponentPieces)
{
if ((enemyPiece.Rank == targetRank) && // Enemy piece is located in
(enemyPiece.File == targetFile) && // the square we just moved to
!enemyPiece.Captured) // and it's not already captured
{
enemyPiece.Captured = true; // Stop drawing it (capture)
moveInfo.CapturedPiece = enemyPiece; // Record the capture
break; // exit the search loop
}
}
// save the last capture state for external callers
lastMoveWasCapture = moveInfo.IsCapture;
Moves.Add(moveInfo);
// Update our FEN
currentFEN = FenParser.ApplyMoveToFEN(currentFEN, moveInfo.ToString());
enPassantValid = FenParser.ExtractEnPassantTarget(currentFEN, out enPassantTarget);
FenParser.ExtractCastlingRights(CurrentFEN, ref whiteCastlingRights, ref blackCastlingRights);
FenParser.ExtractMoveCounts(CurrentFEN, ref halfMoveCount, ref fullMoveCount);
// Flip players - easy to just do here rather than parse the FEN again
activePlayer = OppositeColor(activePlayer);
}
