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140 lines
9.8 KiB
140 lines
9.8 KiB
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import java.util.*;
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// We are making this an *immutable* class. The state that an object has when constructed is its state permanently.
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// Instead of making changes to objects we create new ones (with attemptMove() and the constructor).
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public class GameState {
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Square[] boardSquares; //Tracks the game board as a 1D array of Square objects (effectively 12 x 12) with 2 layers of sentinel squares all around.
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boolean isWhitesTurn; //Knows whose turn it is
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public GameState() {
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//Set turn to white
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isWhitesTurn = true;
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//Initialize squares with legal starting position.
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boardSquares = new Square[] {
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.ROOK, true), new Square(Square.KNIGHT, true), new Square(Square.BISHOP, true), new Square(Square.KING, true), new Square(Square.QUEEN, true), new Square(Square.BISHOP, true), new Square(Square.KNIGHT, true), new Square(Square.ROOK, true), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //white
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.PAWN, true), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //white pawns
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.EMPTY), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.PAWN, false), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //white pawns
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.ROOK, false), new Square(Square.KNIGHT, false), new Square(Square.BISHOP, false), new Square(Square.KING, false), new Square(Square.QUEEN, false), new Square(Square.BISHOP, false), new Square(Square.KNIGHT, false), new Square(Square.ROOK, false), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), //black
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS), new Square(Square.OUT_OF_BOUNDS),
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};
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}
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//Construct a new GameState based on a previous state and a move made on that previous state.
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private GameState(GameState prevState, Move move) {
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ArrayList<Move> moves = prevState.getAllPossibleMoves();
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if (!moves.contains(move)) {
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throw new IllegalArgumentException("Move "+move+" not available for given game state.");
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}
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isWhitesTurn = !prevState.isWhitesTurn;
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boardSquares = new Square[prevState.boardSquares.length];
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for(int i = 0; i < boardSquares.length; i++) {
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boardSquares[i] = new Square(prevState.boardSquares[i]);
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}
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boardSquares[move.getDestIndex()] = new Square(boardSquares[move.getSourceIndex()]);
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boardSquares[move.getSourceIndex()] = new Square(Square.EMPTY);
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//Queening (no underpromotion for now)
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if ((move.getDestRow() == 0 || move.getDestRow() == 7) && boardSquares[move.getDestIndex()].getType() == Square.PAWN) {
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boolean w = boardSquares[move.getDestIndex()].isWhite();
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boardSquares[move.getDestIndex()] = new Square(Square.QUEEN, w); //Make that pawn a queen
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}
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boardSquares[move.getDestIndex()].setHasMoved(); //For knowledge about moving pawns two squares and castling.
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}
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// zero-based index for col and row. Note that -1 and -2 are valid indices into the array, just OUT_OF_BOUNDS.
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public Square getSquare(int col, int row) {
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return boardSquares[12*2 + 2 + col + row * 12];
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}
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public GameState getStateAfterMove(Move m) {
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try {
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return new GameState(this, m); //Create a new object based on this one, update the board state accordingly.
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}
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catch (IllegalArgumentException e) {
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return null; //If it is not a legal move, return null.
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}
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}
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public ArrayList<Move> getAllPossibleMoves() {
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ArrayList<Move> moves = new ArrayList<Move>();
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//Loop through all squares
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for(int index = 0; index < boardSquares.length; index++) {
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int type = boardSquares[index].getType();
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boolean w = boardSquares[index].isWhite();
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boolean pieceMoved = boardSquares[index].isMoved();
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if (type == Square.OUT_OF_BOUNDS) continue;
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if (type == Square.EMPTY) continue;
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//For each square, find all possible places that piece can move to.
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if (type == Square.KING) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12,13,-13,11,-11}, 1, true, true));
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if (type == Square.QUEEN) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12,13,-13,11,-11}, 99, true, true));
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if (type == Square.BISHOP) moves.addAll(findAllMovesFor(index, new int[] {13,-13,11,-11}, 99, true, true));
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if (type == Square.ROOK) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12}, 99, true, true));
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if (type == Square.KNIGHT) moves.addAll(findAllMovesFor(index, new int[] {10,14,23,25,-10,-14,-23,-25}, 1, true, true));
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//white
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if (type == Square.PAWN && w && pieceMoved) moves.addAll(findAllMovesFor(index, new int[] {12}, 1, true, false));
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if (type == Square.PAWN && w && !pieceMoved) moves.addAll(findAllMovesFor(index, new int[] {12}, 2, true, false));
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if (type == Square.PAWN && w) moves.addAll(findAllMovesFor(index, new int[] {11, 13}, 1, false, true));
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//black
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if (type == Square.PAWN && !w && pieceMoved) moves.addAll(findAllMovesFor(index, new int[] {-12}, 1, true, false));
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if (type == Square.PAWN && !w && !pieceMoved) moves.addAll(findAllMovesFor(index, new int[] {-12}, 2, true, false));
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if (type == Square.PAWN && !w) moves.addAll(findAllMovesFor(index, new int[] {-11, -13}, 1, false, true));
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}
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return moves;
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}
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///movementDistance is the number of times that piece can move in the given directions.
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private ArrayList<Move> findAllMovesFor(int index, int[] directions, int movementDistance, boolean canMove, boolean canCapture) {
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ArrayList<Move> moves = new ArrayList<Move>();
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if (boardSquares[index].isWhite() != isWhitesTurn) return moves; //don't move other person's pieces!
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//loop through the directions, see if they work - return the resulting arraylist.
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for(int dir : directions) {
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int destIndex = index;
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int numMoves = movementDistance;
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do {
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destIndex += dir;
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int type = boardSquares[destIndex].getType();
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if (type == Square.OUT_OF_BOUNDS) break;
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if (type == Square.EMPTY && canMove ||
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type != Square.EMPTY && type != Square.OUT_OF_BOUNDS && boardSquares[destIndex].isWhite() != isWhitesTurn && canCapture) {
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moves.add(new Move(index, destIndex));
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}
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numMoves--;
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} while(boardSquares[destIndex].getType() == Square.EMPTY && numMoves > 0);
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}
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return moves;
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}
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public boolean isWhitesTurn() {
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return isWhitesTurn;
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}
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// TODO: should also include information regarding check, checkmate, and stalemate.
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public String getFeedback() {
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return isWhitesTurn ? "White's turn" : "Black's turn";
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}
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}
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