Day 50

Day 43, 45, 46 (chess application design)/Chess.java

@@ -23,7 +23,7 @@ public class Chess extends Application {
 
 	//User's first click for a move.
 	private Integer clickRow;  //null means no first click made currently.
-	private Integer clickColumn;
+	private Integer clickCol;
 
 	private GraphicsContext graphics;
 	private TextArea moveHistoryTextArea;
@@ -87,7 +87,7 @@ public class Chess extends Application {
 		moveNotationHistory = new ArrayList<String>();
 
 		//No clicks yet
-		clickRow = clickColumn = null;
+		clickRow = clickCol = null;
 
 		//Set up mouse/click events
 		board.setOnMousePressed(this::mouseClick);
@@ -96,7 +96,7 @@ public class Chess extends Application {
 		aiMove.setOnAction(this::moveAI);
 
 		//Refresh the board
-		paintBoard();
+		updateScreen();
 
 		//Fix mysterious broken width and prevent shrinking window
 		stage.setWidth(664);
@@ -106,7 +106,7 @@ public class Chess extends Application {
 		stage.show();
 	}
 
-	private void paintBoard() {
+	private void updateScreen() {
 		for(int x = 0; x < 8; x++) {
 			for(int y = 0; y < 8; y++) {
 				graphics.setFill((x + y) % 2 == 0 ? Color.BURLYWOOD : Color.FORESTGREEN);
@@ -134,37 +134,76 @@ public class Chess extends Application {
 
 	//Reset to the intial game position.
 	public void reset(ActionEvent e) {
-		System.out.println(board().getAllPossibleMoves() );
-		//Set up the initial board
-		//Clear out clickRo and clickCol
-		//Clera out all the histories.
+		System.out.println(board().getAllPossibleMoves());
 
+		//Clear out all the histories
+		gameStateHistory = new ArrayList<GameState>();
+		gameStateHistory.add(new GameState()); //Set up the initial board
+		moveHistory = new ArrayList<Move>();
+		moveNotationHistory = new ArrayList<String>();
+
+		//Clear out clickRow and clickCol
+		clickRow = clickCol = null;
+		moveHistoryTextArea.setText("");
+		updateScreen();
 	}
 
 	//AI makes a move
 	public void moveAI(ActionEvent e) {
 		//Ask the gameState for a list of all legal moves.
+		ArrayList<Move> a = board().getAllPossibleMoves();
+		if (a.size() <= 0) return; //no moves.
+
 		//Get one of those in the list uniformly at random.
-//		makeMove(...);
+		int r = (int)(Math.random() * a.size());
+		makeMove(a.get(r));
 	}
 
 	private void makeMove(Move move) {
 		//Clone the gameState object for the current state of the game, tell it to make the move, add it to the move history
-		//add the notation for it
+		GameState g = board().getStateAfterMove(move);
+		if (g==null) return; //didn't actually move it; must not have been legal.
+		gameStateHistory.add(g);
+
 		//add the move to the history as well
+		moveHistory.add(move);
+
+		//add the notation for it
+		moveNotationHistory.add(move+"");
+
+		//Refresh the board
+		updateScreen();
 	}
 
 	//For the human moving
 	public void mouseClick(MouseEvent e) {
 		//If it is the first click (null check) then record it, updtae the GUI to show highlighting
 		//else attempt the move:
+		int x = (int)(e.getX() / 50);
+		int y = (int)(e.getY() / 50);
 
-//		makeMove(...);
+		if (board().getSquare(x,y).isWhite() == board().isWhitesTurn() && board().getSquare(x,y).getType() != Square.EMPTY) { //if clicking on own piece...
+			clickRow = y;
+			clickCol = x;
+		}
+		else if (clickRow != null) {
+			makeMove(new Move(clickCol, clickRow, x, y));
+			clickRow = clickCol = null;
+		}
+		updateScreen();
 	}
 
 	//Undo button for the most recent move
 	public void undo(ActionEvent e) {
 		//Pop those 3 history object things and update the GUI.
+		if (gameStateHistory.size() <= 1) return; //can't pop the initial state.
+
+		//Pop those 3 history object things and update the GUI.
+		gameStateHistory.remove(gameStateHistory.size() - 1);
+		moveHistory.remove(moveHistory.size() - 1);
+		moveNotationHistory.remove(moveNotationHistory.size() - 1);
+		clickRow = clickCol = null;
+		updateScreen();
 	}
 
 }

Day 43, 45, 46 (chess application design)/GameState.java

@@ -32,15 +32,36 @@ public class GameState {
 
 	}
 
+	//Construct a new GameState based on a previous state and a move made on that previous state.
+	private GameState(GameState prevState, Move move) {
+		ArrayList<Move> moves = prevState.getAllPossibleMoves();
+		if (!moves.contains(move)) {
+			throw new IllegalArgumentException("Move "+move+" not available for given game state.");
+		}
+
+		isWhitesTurn = !prevState.isWhitesTurn;
+		boardSquares = new Square[prevState.boardSquares.length];
+		for(int i = 0; i < boardSquares.length; i++) {
+			boardSquares[i] = new Square(prevState.boardSquares[i]);
+		}
+		boardSquares[move.getDestIndex()] = new Square(boardSquares[move.getSourceIndex()]);
+		boardSquares[move.getSourceIndex()] = new Square(Square.EMPTY);
+
+	}
+
+
 	// zero-based index for col and row.  Note that -1 and -2 are valid indices into the array, just OUT_OF_BOUNDS.
 	public Square getSquare(int col, int row) {
 		return boardSquares[12*2 + 2 + col + row * 12];
 	}
 
 	public GameState getStateAfterMove(Move m) {
-		//See if it is legal.  If not, return null.
-		//Create a new object based on this one, update the board state accordingly.
-		return null;
+		try {
+			return new GameState(this, m); //Create a new object based on this one, update the board state accordingly.
+		}
+		catch (IllegalArgumentException e) {
+			return null; //If it is not a legal move, return null.
+		}
 	}
 
 	public ArrayList<Move> getAllPossibleMoves() {
@@ -49,6 +70,7 @@ public class GameState {
 		//Loop through all squares
 		for(int index = 0; index < boardSquares.length; index++) {
 			int type = boardSquares[index].getType();
+			boolean w = boardSquares[index].isWhite();
 			if (type == Square.OUT_OF_BOUNDS) continue;
 			if (type == Square.EMPTY) continue;
 
@@ -58,6 +80,8 @@ public class GameState {
 			if (type == Square.BISHOP) moves.addAll(findAllMovesFor(index, new int[] {13,-13,11,-11}, true));
 			if (type == Square.ROOK) moves.addAll(findAllMovesFor(index, new int[] {1,-1,12,-12}, true));
 			if (type == Square.KNIGHT) moves.addAll(findAllMovesFor(index, new int[] {10,14,23,25,-10,-14,-23,-25}, false));
+			if (type == Square.PAWN && w) moves.addAll(findAllMovesFor(index, new int[] {12}, false));
+			if (type == Square.PAWN && !w) moves.addAll(findAllMovesFor(index, new int[] {-12}, false));
 		}
 
 		return moves;
@@ -65,21 +89,28 @@ public class GameState {
 
 	private ArrayList<Move> findAllMovesFor(int index, int[] directions, boolean canMoveMultipleSquares) {
 		ArrayList<Move> moves = new ArrayList<Move>();
+		if (boardSquares[index].isWhite() != isWhitesTurn) return moves; //don't move other person's pieces!
+
 		//loop through the directions, see if they work - return the resulting arraylist.
 		for(int dir : directions) {
-			int destIndex = index + dir;
-			int type = boardSquares[destIndex].getType();
-			if (boardSquares[index].isWhite() != isWhitesTurn) continue; //don't move other person's pieces!
-
-			if (type == Square.OUT_OF_BOUNDS) continue;
-			if (type == Square.EMPTY || boardSquares[destIndex].isWhite() != isWhitesTurn) {
-				moves.add(new Move(index, destIndex));
-			}
+			int destIndex = index;
+			do {
+				destIndex += dir;
+				int type = boardSquares[destIndex].getType();
+				if (type == Square.OUT_OF_BOUNDS) break;
+				if (type == Square.EMPTY || boardSquares[destIndex].isWhite() != isWhitesTurn) {
+					moves.add(new Move(index, destIndex));
+				}
+			} while(boardSquares[destIndex].getType() == Square.EMPTY && canMoveMultipleSquares);
 
 		}
 		return moves;
 	}
 
+	public boolean isWhitesTurn() {
+		return isWhitesTurn;
+	}
+
 	// returns something like "checkmate", "stalemate", etc.
 	public String getFeedback() {
 		return null;

Day 43, 45, 46 (chess application design)/Move.java

@@ -1,25 +1,33 @@
 
 public class Move {
 	//source and dest coordinates
-	int startIndex;
+	int sourceIndex;
 	int destIndex;
 
-
-	public Move(int startIndex, int destIndex) {
-		this.startIndex = startIndex;
+	public Move(int sourceIndex, int destIndex) {
+		this.sourceIndex = sourceIndex;
 		this.destIndex = destIndex;
 	}
 
-	public Move(int sourceRow, int sourceColumn, int destinationRow, int destinationColumn) {
-		//TODO
+	public Move(int sourceColumn, int sourceRow, int destColumn, int destRow) {
+		sourceIndex = sourceRow * 12 + sourceColumn + 2 + 12*2;
+		destIndex = destRow * 12 + destColumn + 2 + 12*2;
+	}
+
+	public int getSourceIndex() {
+		return sourceIndex;
+	}
+
+	public int getDestIndex() {
+		return destIndex;
 	}
 
 	public int getSourceRow() {
-		return startIndex / 12 - 2;
+		return sourceIndex / 12 - 2;
 	}
 
 	public int getSourceCol() {
-		return startIndex % 12 - 2;
+		return sourceIndex % 12 - 2;
 	}
 
 	public int getDestRow() {
@@ -31,10 +39,23 @@ public class Move {
 		return destIndex % 12 - 2;
 	}
 
+	private String letterFor(int col) {
+		return "abcdefgh".substring(col, col+1);
+	}
 
-	//returns something like e2-e4 or Qc8++
+	//returns something like e2-e4
 	public String toString() {
-		return "("+getSourceRow()+","+getSourceCol() + ") -> " + "("+getDestRow()+","+getDestCol() + ")";
+		return letterFor(getSourceCol())+(getSourceRow()+1) + "-" + letterFor(getDestCol())+(getDestRow()+1);
+	}
+
+	public boolean equals(Object obj) {
+		if (obj instanceof Move) {
+			Move move = (Move)obj;
+			return (move.sourceIndex == sourceIndex && move.destIndex == destIndex);
+		}
+		else {
+			return false; //not even a move object
+		}
 	}
 
 }

Day 43, 45, 46 (chess application design)/Square.java

@@ -17,6 +17,11 @@ public class Square {
 	//boolean Knowledge of whether or not this piece moved yet (for castling)
 	//boolean for off-the-board square
 
+	public Square(Square s) {
+		type = s.type;
+		isWhite = s.isWhite;
+	}
+
 	public Square(int type) {
 		this(type, false);
 	}

Day 43, 45, 46 (chess application design)/defensive programming.txt

@@ -0,0 +1,21 @@
+
+Cloning: the default choice is a deep copy (although be aware of memory usage).
+
+Common options for handling errors:
+	* Close program
+	* Throw exception
+	* Use a reasonable or neutral value
+	* Log the error
+	* Print the error
+	* Do nothing
+	[* Use an assert if you want an error thrown, but only during development]
+
+Example of an assert (in Java, assertions are enabled by running it with the -ea flag)
+	lat = ...  //calculation happens here
+
+	//We want an error thrown if it's out of bounds, but only during development
+	assert (lat >= -90 && lat <= 90) : "Latitude out of bounds";
+
+	if (lat > 90) lat = 90;
+	if (lat < -90) lat = -90;
+