public void undoLastMove() {
// Check that we have a move to undo
if (moves.isEmpty()) {
throw new InternalError("No move available to undo");
}
final Move lastMove = getLastMove();
final Point from = lastMove.getFrom();
final Point to = lastMove.getTo();
final Piece piece = lastMove.getPiece();
squares[from.getX()][from.getY()].setPiece(piece);
if (lastMove.isLeftCastling()) {
squares[to.getX()][to.getY()].setPiece(null);
if (piece.getColor() == Color.W) {
setPiece(Piece.WHITE_ROOK, King.W_LEFT_ROOK);
setPiece(null, to.incrementX(1));
} else {
setPiece(Piece.BLACK_ROOK, King.B_LEFT_ROOK);
setPiece(null, to.incrementX(1));
}
} else if (lastMove.isRightCastling()) {
squares[to.getX()][to.getY()].setPiece(null);
if (piece.getColor() == Color.W) {
setPiece(Piece.WHITE_ROOK, King.W_RIGHT_ROOK);
setPiece(null, to.decrementX(1));
} else {
setPiece(Piece.BLACK_ROOK, King.B_RIGHT_ROOK);
setPiece(null, to.decrementX(1));
}
} else {
final Piece captured = lastMove.getCaptured();
// Undoing an en passant move?
if (lastMove.isEnPassant()) {
if (captured.getColor() == Color.B) {
squares[to.getX()][to.getY() - 1].setPiece(captured);
} else {
squares[to.getX()][to.getY() + 1].setPiece(captured);
}
squares[to.getX()][to.getY()].setPiece(null);
} else {
squares[to.getX()][to.getY()].setPiece(captured);
}
// Keep track of the kings
if (piece == WHITE_KING) {
whiteKing = squares[from.getX()][from.getY()];
} else if (piece == BLACK_KING) {
blackKing = squares[from.getX()][from.getY()];
}
}
// Remove move from history
moves.remove(moves.size() - 1);
}
