Fixed movement on a pieces and user input

Don't know where my original Main.java commit went, but here it is.

Michael _Edit's_(non_destructive)/Bishop.java

@@ -0,0 +1,31 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+import static project.ui.Display.loadImage;
+
+public class Bishop extends ChessPiece {
+
+    private Image whiteBishop = loadImage("./resources/chess_piece_2_black_bishop.png");
+    private Image blackBishop = loadImage("./resources/chess_piece_2_white_bishop.png");
+
+    public Bishop(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        if (isWhite)
+            return whiteBishop;
+        return blackBishop;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        return new ArrayList<Move>(super.getDiagonalMoves(b.size()));
+    }
+
+    public Bishop clone () {
+        return new Bishop(this.b,this.isWhite,this.x,this.y);
+    }
+}

Michael _Edit's_(non_destructive)/Board.java

@@ -0,0 +1,141 @@
+package project.chess;
+
+import java.util.ArrayList;
+
+public class Board {
+
+    private final ChessPiece[][] board = new ChessPiece[8][8];
+
+    /**
+     * create a basic chess board in default configuration
+     */
+    public Board(){
+        for (int i = 0; i < size(); i++) {
+            board[i][1] = new Pawn(this, true, i, 1);
+            board[i][size() - 2] = new Pawn(this, false, i, size() - 2);
+        }
+        // white
+        board[0][0] = new Rook(this, true,0, 0);
+        board[size()-1][0] = new Rook(this, true, size() - 1, 0);
+        board[1][0] = new Knight(this, true, 1, 0);
+        board[size()-2][0] = new Knight(this, true, size() - 2, 0);
+        board[2][0] = new Bishop(this, true, 2, 0);
+        board[size()-3][0] = new Bishop(this, true, size() - 3, 0);
+        board[3][0] = new Queen(this, true, 3, 0);
+        board[size()-4][0] = new King(this, true, size() - 4, 0);
+
+        // black
+        board[0][size()-1] = new Rook(this, false,0, size()-1);
+        board[size()-1][size()-1] = new Rook(this, false, size() - 1, size()-1);
+        board[1][size()-1] = new Knight(this, false, 1, size()-1);
+        board[size()-2][size()-1] = new Knight(this, false, size() - 2, size()-1);
+        board[2][size()-1] = new Bishop(this, false, 2, size()-1);
+        board[size()-3][size()-1] = new Bishop(this, false, size() - 3, size()-1);
+        board[3][size()-1] = new Queen(this, false, 3, size()-1);
+        board[size()-4][size()-1] = new King(this, false, size() - 4, size()-1);
+    }
+
+    public boolean movePiece(Move movingPiece, Move newPos){
+        return movePiece(movingPiece.getX(), movingPiece.getY(), newPos.getX(), newPos.getY());
+    }
+
+    public boolean movePiece(int x, int y, int newX, int newY){
+        // System.out.println(x + " " + y + " || " + newX + " " + newY);
+        ChessPiece selectedPiece;
+        // make sure the place we are moving from has a piece
+        if ((selectedPiece = get(x, y)) == null)
+            return false;
+        ArrayList<Move> moves;
+        moves = selectedPiece.getMoves();
+        for (Move m : moves){
+            // reject the moves that don't correspond to where we want to move to.
+            if (m.getX() != newX || m.getY() != newY)
+                continue;
+            ChessPiece movedPiece = get(m);
+            // make sure they are of the same color. Since we know this move is the position we want to move to
+            // we can early exit because we are not allowed to move on top of our own pieces
+            if (movedPiece != null && selectedPiece.isWhite == movedPiece.isWhite)
+                return false;
+            // if we were unable to set the piece down we failed to move the piece
+            if (!set(m, selectedPiece))
+                return false;
+            // run special conditions. Only matters for pieces which have special conditions, since is defaulted to empty body.
+            if (movedPiece != null)
+                selectedPiece.applySpecialMove(m);
+            set(x, y, null);
+            return true;
+        }
+        return false;
+    }
+
+    public ArrayList<Board> getMoves(boolean isWhitesTurn) {
+        ArrayList<Board> moveStates = new ArrayList<>();
+        Board curr;
+
+        for (int i = 0; i < board.length; i++) {
+            for (int j = 0; j < board[0].length; j++) {
+                if ((board[i][j] = get(i, j)) == null || (isWhitesTurn && !board[i][j].isWhite()) ||
+                        (!isWhitesTurn && board[i][j].isWhite()) ) continue;
+                for (Move pieceMove : board[i][j].getMoves()) {
+                    curr = deepCopy();
+                    curr.movePiece(board[i][j].x,board[i][j].y,pieceMove.getX(),pieceMove.getY());
+                    moveStates.add(deepCopy());
+                }
+            }
+        }
+        return moveStates;
+    }
+
+    public int evaluate () { // !!!!!!!! Fix this, add actual heuristic evaluation
+        return (int)Math.random()*900;
+    }
+
+    public Board deepCopy () {
+        Board temp = new Board();
+
+        for (int i = 0; i < temp.board.length; i++) {
+            for (int j = 0; j < temp.board[0].length; j++) {
+                try {
+                    if (this.board[i][j] == null) {
+                        temp.board[i][j] = null;
+                        continue;
+                    }
+
+                    temp.board[i][j] = this.board[i][j].clone();
+                } catch (Exception e) { e.printStackTrace();}
+            }
+        }
+
+        return temp;
+    }
+
+    public ChessPiece get(Move m){
+        return get(m.getX(), m.getY());
+    }
+
+    public ChessPiece get(int x, int y){
+        if (x < 0 || x >= board.length)
+            return null;
+        if (y < 0 || y >= board.length)
+            return null;
+        return board[x][y];
+    }
+
+    public boolean set(Move m, ChessPiece piece) {
+        return set(m.getX(), m.getY(), piece);
+    }
+
+    protected boolean set(int x, int y, ChessPiece piece){
+        if (x < 0 || x >= board.length)
+            return false;
+        if (y < 0 || y >= board.length)
+            return false;
+        board[x][y] = piece;
+        return true;
+    }
+
+    public int size(){
+        return board.length;
+    }
+
+}

Michael _Edit's_(non_destructive)/ChessPiece.java

@@ -0,0 +1,68 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+public abstract class ChessPiece {
+
+    protected Board b;
+    protected int x, y;
+    protected boolean isInDanger, isWhite;
+    protected boolean isFirstMove = true;
+
+    public ChessPiece(Board b, boolean isWhite, int x, int y) {
+        this.b = b;
+        this.x = x;
+        this.y = y;
+        this.isWhite = isWhite;
+    }
+
+    public void setInDanger(boolean isInDanger){
+        this.isInDanger = isInDanger;
+    }
+
+    public boolean isWhite(){
+        return isWhite;
+    }
+    public Move getPosition(){
+        return new Move(x, y);
+    }
+
+    public boolean isFirstMove(){
+        return isFirstMove;
+    }
+
+    public void setMoved(){
+        isFirstMove = false;
+    }
+
+    public abstract ArrayList<Move> getMoves();
+    public abstract Image getImage();
+    public void applySpecialMove(Move moveWithSpecial){}
+
+    protected ArrayList<Move> getCardinalMoves(int length){
+        ArrayList<Move> moves = new ArrayList<Move>();
+        for (int i = 1; i <= length; i++){
+            // cardinals
+            moves.add(new Move(x - i, y));
+            moves.add(new Move(x + i, y));
+            moves.add(new Move(x, y - i));
+            moves.add(new Move(x, y + i));
+        }
+        return moves;
+    }
+
+    protected ArrayList<Move> getDiagonalMoves(int length){
+        ArrayList<Move> moves = new ArrayList<Move>();
+        for (int i = 1; i <= length; i++){
+            // cardinals
+            moves.add(new Move(x - i, y - i));
+            moves.add(new Move(x + i, y + i));
+            moves.add(new Move(x + i, y - i));
+            moves.add(new Move(x - i, y + i));
+        }
+        return moves;
+    }
+
+    public abstract ChessPiece clone();
+}

Michael _Edit's_(non_destructive)/King.java

@@ -0,0 +1,79 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+import static project.ui.Display.loadImage;
+
+public class King extends ChessPiece {
+
+    private final Image whiteKing = loadImage("./resources/chess_piece_2_black_king.png");
+    private final Image blackKing = loadImage("./resources/chess_piece_2_white_king.png");
+
+    public King(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        if (isWhite)
+            return whiteKing;
+        return blackKing;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        ArrayList<Move> moves = new ArrayList<Move>();
+        moves.addAll(super.getCardinalMoves(1));
+        moves.addAll(super.getDiagonalMoves(1));
+        if (isFirstMove){
+            ChessPiece rook = null;
+            // castling
+            if (isWhite){
+                if ((rook = b.get(0, 0)) != null && checkIfRookValid(rook))
+                    moves.add(new Move(2, 0, Move.SpecialConditions.leftCastle));
+                if ((rook = b.get(b.size() - 1, 0)) != null && checkIfRookValid(rook))
+                    moves.add(new Move(b.size() - 2, 0, Move.SpecialConditions.rightCastle));
+            } else {
+                if ((rook = b.get(0, b.size()-1)) != null && checkIfRookValid(rook))
+                    moves.add(new Move(2, b.size()-1, Move.SpecialConditions.leftCastle));
+                if ((rook = b.get(b.size() - 1, b.size()-1)) != null && checkIfRookValid(rook))
+                    moves.add(new Move(b.size() - 2, b.size()-1, Move.SpecialConditions.rightCastle));
+            }
+        }
+        return moves;
+    }
+
+    @Override
+    public void applySpecialMove(Move moveWithSpecial){
+        Move.SpecialConditions specialCondition;
+        specialCondition = moveWithSpecial.getSpecialCondition();
+        if(specialCondition == Move.SpecialConditions.leftCastle)
+            castleLeft();
+        else if (specialCondition == Move.SpecialConditions.rightCastle)
+            castleRight();
+    }
+
+    private void castleRight(){
+        // casting has to move the rook on the right size of the king from white's perspective
+        if (this.isWhite)
+            b.set(b.size()-3, 0, b.get(b.size()-1, 0));
+        else
+            b.set(b.size()-3, b.size()-1, b.get(b.size()-1, b.size()-1));
+    }
+
+    private boolean checkIfRookValid(ChessPiece piece){
+        return piece.isFirstMove() && piece instanceof Rook;
+    }
+
+    private void castleLeft(){
+        // casting has to move the rook on the left size of the king from white's perspective
+        if (this.isWhite)
+            b.set(3, 0, b.get(0, 0));
+        else
+            b.set(3, b.size()-1, b.get(0, b.size()-1));
+    }
+
+    public King clone () {
+        return new King(this.b,this.isWhite,this.x,this.y);
+    }
+}

Michael _Edit's_(non_destructive)/Knight.java

@@ -0,0 +1,40 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+import static project.ui.Display.loadImage;
+
+public class Knight extends ChessPiece {
+
+    private Image whiteKnight = loadImage("./resources/chess_piece_2_black_knight.png");
+    private Image blackKnight = loadImage("./resources/chess_piece_2_white_knight.png");
+
+    public Knight(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        if (isWhite)
+            return whiteKnight;
+        return blackKnight;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        ArrayList<Move> moves = new ArrayList<Move>();
+        moves.add(new Move(x + 2, y + 1));
+        moves.add(new Move(x + 2, y - 1));
+        moves.add(new Move(x - 2, y + 1));
+        moves.add(new Move(x - 2, y - 1));
+        moves.add(new Move(x - 1, y - 2));
+        moves.add(new Move(x + 1, y - 2));
+        moves.add(new Move(x - 1, y + 2));
+        moves.add(new Move(x + 1, y + 2));
+        return moves;
+    }
+
+    public Knight clone () {
+        return new Knight(this.b,this.isWhite,this.x,this.y);
+    }
+}

Michael _Edit's_(non_destructive)/Main.java

@@ -0,0 +1,97 @@
+package project;
+
+import project.chess.Board;
+import project.chess.Move;
+import project.ui.Display;
+
+import java.util.ArrayList;
+import java.util.concurrent.TimeUnit;
+
+public class Main {
+    public static void main(String[] args) {
+        Board mainBoard = new Board();
+
+        int maxDepth = 2;
+        Board[] bestStates = new Board[maxDepth];
+
+        minMax(mainBoard,bestStates,maxDepth,true);
+
+        System.out.println("Ai Done Computing");
+        
+        int counter = 0;
+
+        // mainBoard.getMoves();
+
+        // display stuff //
+        Display display = new Display(mainBoard);
+        long frames = 0;
+        long lastTime = System.currentTimeMillis();
+        long frameTime = System.currentTimeMillis();
+        while(display.update(mainBoard)){
+            display.repaint();
+            // limit usage of system resources by slowing the speed down to 60 fps.
+            while ((System.currentTimeMillis() - frameTime) < 64f){
+                Thread.yield();
+            }
+            frameTime = System.currentTimeMillis();
+
+            // print out the FPS of the display.
+            frames++;
+            if (System.currentTimeMillis() - lastTime > 1000){
+                System.out.println("FPS: " + frames);
+                frames = 0;
+                lastTime = System.currentTimeMillis();
+            }
+
+            try {
+                TimeUnit.SECONDS.sleep(1);
+            } catch (Exception ignored) {}
+
+            mainBoard = bestStates[counter%maxDepth];
+
+            counter++;
+
+        }
+        System.out.println("Hello world!");
+
+
+    }
+
+    /*
+    public int alphaBeta (Board position, int depth, int alpha, int beta, boolean maximizing) {
+        if (depth == 0 || position.kingInDanger) return Board.evaluate(position);
+
+        if (maximizing) {
+            int maxEval = Integer.MIN_VALUE;
+            position.
+        }
+    } */
+
+    public static int minMax (Board position, Board[] bestStates, int depth, boolean maximizing) {
+        if (depth == 0) {
+            bestStates[depth] = position;
+            return position.evaluate();
+        }
+
+        System.out.println(depth);
+
+        if (maximizing) {
+            int maxEval = Integer.MIN_VALUE;
+            for (Board state: position.getMoves(maximizing) ) {
+                int eval = minMax(state,bestStates,depth-1, false);
+                maxEval = Math.max(maxEval,eval);
+            }
+            bestStates[depth-1] = position;
+            return maxEval;
+        } else {
+            int minEval = Integer.MAX_VALUE;
+            for (Board state: position.getMoves(maximizing) ) {
+                int eval = minMax(state,bestStates,depth-1, true);
+                minEval = Math.min(minEval,eval);
+            }
+            bestStates[depth-1] = position;
+            return minEval;
+        }
+    }
+
+}

Michael _Edit's_(non_destructive)/Pawn.java

@@ -0,0 +1,88 @@
+package project.chess;
+
+import project.ui.Display;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+public class Pawn extends ChessPiece {
+
+    private Image white = Display.loadImage("./resources/chess_piece_2_black_pawn.png");
+    private Image black = Display.loadImage("./resources/chess_piece_2_white_pawn.png");
+
+    public Pawn(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        if (isWhite)
+            return white;
+        return black;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        ArrayList<Move> moves = new ArrayList<Move>();
+        if (isWhite) {
+            moves.add(new Move(x, y + 1));
+            if (isFirstMove)
+                moves.add(new Move(x, y + 2));
+        } else {
+            moves.add(new Move(x, y - 1));
+            if (isFirstMove)
+                moves.add(new Move(x, y - 2));
+        }
+        ChessPiece neighbour = null;
+
+        if (isWhite){
+            // En passant
+            if ((neighbour = b.get(x-1, y)) != null && checkNeighbourEnPassant(neighbour))
+                moves.add(new Move(x-1, y + 1, Move.SpecialConditions.leftEnPassant));
+            // En passant
+            if ((neighbour = b.get(x+1, y)) != null && checkNeighbourEnPassant(neighbour))
+                moves.add(new Move(x+1, + 1, Move.SpecialConditions.rightEnPassant));
+        } else {
+            // unfortunately have to flip the direction depending on player type
+            // En passant
+            if ((neighbour = b.get(x-1, y)) != null && checkNeighbourEnPassant(neighbour))
+                moves.add(new Move(x-1, y - 1, Move.SpecialConditions.leftEnPassant));
+            // En passant
+            if ((neighbour = b.get(x+1, y)) != null && checkNeighbourEnPassant(neighbour))
+                moves.add(new Move(x+1, - 1, Move.SpecialConditions.rightEnPassant));
+        }
+
+        return moves;
+    }
+
+    private boolean checkNeighbourEnPassant(ChessPiece neighbour){
+        return neighbour instanceof Pawn && ((Pawn) neighbour).isFirstMove() && neighbour.isWhite != this.isWhite;
+    }
+
+    @Override
+    public void applySpecialMove(Move moveWithSpecial){
+        Move.SpecialConditions specialCondition;
+        specialCondition = moveWithSpecial.getSpecialCondition();
+        if(specialCondition == Move.SpecialConditions.leftEnPassant)
+            enPassantLeft();
+        else if (specialCondition == Move.SpecialConditions.rightEnPassant)
+            enPassantRight();
+    }
+
+    private void enPassantLeft(){
+        if (isWhite)
+            b.set(x-1, y, null);
+        else
+            b.set(x+1, y, null);
+    }
+
+    private void enPassantRight(){
+        if (isWhite)
+            b.set(x+1, y, null);
+        else
+            b.set(x-1, y, null);
+    }
+
+    public Pawn clone () {
+        return new Pawn(this.b,this.isWhite,this.x,this.y);
+    }
+}

Michael _Edit's_(non_destructive)/Queen.java

@@ -0,0 +1,34 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+import static project.ui.Display.loadImage;
+
+public class Queen extends ChessPiece {
+
+    private Image whiteQueen = loadImage("./resources/chess_piece_2_black_queen.png");
+    private Image blackQueen = loadImage("./resources/chess_piece_2_white_queen.png");
+
+    public Queen(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        if (isWhite)
+            return whiteQueen;
+        return blackQueen;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        ArrayList<Move> moves = new ArrayList<Move>();
+        moves.addAll(super.getCardinalMoves(b.size()));
+        moves.addAll(super.getDiagonalMoves(b.size()));
+        return moves;
+    }
+
+    public Queen clone () {
+        return new Queen(this.b,this.isWhite,this.x,this.y);
+    }
+}

Michael _Edit's_(non_destructive)/Rook.java

@@ -0,0 +1,29 @@
+package project.chess;
+
+import java.awt.*;
+import java.util.ArrayList;
+
+import static project.ui.Display.loadImage;
+
+public class Rook extends ChessPiece {
+
+    private Image whiteRook = loadImage("./resources/chess_piece_2_black_rook.png");
+    private Image blackRook = loadImage("./resources/chess_piece_2_white_rook.png");
+
+    public Rook(Board b, boolean isWhite, int x, int y) {
+        super(b,isWhite,x,y);
+    }
+
+    public Image getImage(){
+        return isWhite ? whiteRook : blackRook;
+    }
+
+    @Override
+    public ArrayList<Move> getMoves() {
+        return new ArrayList<Move>(super.getCardinalMoves(b.size()));
+    }
+
+    public Rook clone () {
+        return new Rook(this.b,this.isWhite,this.x,this.y);
+    }
+}

src/chess/Bishop.java

@@ -22,6 +22,6 @@ public class Bishop extends ChessPiece {
 
     @Override
     public ArrayList<Move> getMoves() {
-        return new ArrayList<Move>(super.getDiagonalMoves(b.size()));
+        return prune(super.getDiagonalMoves(b.size()));
     }
 }

src/chess/Board.java

@@ -56,9 +56,9 @@ public class Board {
             // if we were unable to set the piece down we failed to move the piece
             if (!set(m, selectedPiece))
                 return false;
+            selectedPiece.move(m);
             // run special conditions. Only matters for pieces which have special conditions, since is defaulted to empty body.
-            if (movedPiece != null)
-                selectedPiece.applySpecialMove(m);
+            selectedPiece.applySpecialMove(m);
             set(x, y, null);
             return true;
         }
@@ -66,6 +66,8 @@ public class Board {
     }
 
     public ChessPiece get(Move m){
+        if (m == null)
+            return null;
         return get(m.getX(), m.getY());
     }
 
@@ -78,10 +80,12 @@ public class Board {
     }
 
     public boolean set(Move m, ChessPiece piece) {
+        if (m == null)
+            return false;
         return set(m.getX(), m.getY(), piece);
     }
 
-    protected boolean set(int x, int y, ChessPiece piece){
+    public boolean set(int x, int y, ChessPiece piece){
         if (x < 0 || x >= board.length)
             return false;
         if (y < 0 || y >= board.length)
@@ -90,6 +94,14 @@ public class Board {
         return true;
     }
 
+    protected Move checkIfMoveValid(Move m, boolean isWhite){
+        if (m == null)
+            return null;
+        if (get(m) != null && get(m).isWhite == isWhite)
+            return null;
+        return m;
+    }
+
     public int size(){
         return board.length;
     }

src/chess/ChessPiece.java

@@ -8,7 +8,7 @@ public abstract class ChessPiece {
     protected Board b;
     protected int x, y;
     protected boolean isInDanger, isWhite;
-    protected boolean isFirstMove = true;
+    protected int moveCount = 0;
 
     public ChessPiece(Board b, boolean isWhite, int x, int y) {
         this.b = b;
@@ -29,11 +29,16 @@ public abstract class ChessPiece {
     }
 
     public boolean isFirstMove(){
-        return isFirstMove;
+        return moveCount < 1;
+    }
+    public boolean isSecondMove(){
+        return moveCount <= 1;
     }
 
-    public void setMoved(){
-        isFirstMove = false;
+    public void move(Move m){
+        this.x = m.getX();
+        this.y = m.getY();
+        this.moveCount++;
     }
 
     public abstract ArrayList<Move> getMoves();
@@ -42,26 +47,81 @@ public abstract class ChessPiece {
 
     protected ArrayList<Move> getCardinalMoves(int length){
         ArrayList<Move> moves = new ArrayList<Move>();
+        // cardinals
         for (int i = 1; i <= length; i++){
-            // cardinals
-            moves.add(new Move(x - i, y));
-            moves.add(new Move(x + i, y));
-            moves.add(new Move(x, y - i));
-            moves.add(new Move(x, y + i));
+            if (add(moves, new Move(x - i, y)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x + i, y)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x, y - i)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x, y + i)))
+                break;
         }
         return moves;
     }
 
     protected ArrayList<Move> getDiagonalMoves(int length){
         ArrayList<Move> moves = new ArrayList<Move>();
+        // diagonals
         for (int i = 1; i <= length; i++){
-            // cardinals
-            moves.add(new Move(x - i, y - i));
-            moves.add(new Move(x + i, y + i));
-            moves.add(new Move(x + i, y - i));
-            moves.add(new Move(x - i, y + i));
+            if (add(moves, new Move(x - i, y - i)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x - i, y + i)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x + i, y - i)))
+                break;
+        }
+        for (int i = 1; i <= length; i++){
+            if (add(moves, new Move(x + i, y + i)))
+                break;
         }
         return moves;
     }
 
+    protected ArrayList<Move> prune(ArrayList<Move> moves){
+        var prunedMoves = new ArrayList<Move>();
+        // get rid of impossible moves
+        for (Move m : moves){
+            if (m == null)
+                continue;
+            if (m.getX() < 0 || m.getX() >= b.size())
+                continue;
+            if (m.getY() < 0 || m.getY() >= b.size())
+                continue;
+            prunedMoves.add(m);
+        }
+
+        return prunedMoves;
+    }
+
+    /**
+     * Checks to make sure that the proposed move is valid.
+     * @param moves array to add to
+     * @param move move to add to the array
+     * @return true if we need to stop here. (Break the loop)
+     */
+    private boolean add(ArrayList<Move> moves, Move move){
+        var m = b.get(move);
+        if (m != null && m.isWhite != isWhite) {
+            moves.add(b.checkIfMoveValid(move, isWhite));
+            return true;
+        } else {
+            if (m != null)
+                return true;
+            moves.add(b.checkIfMoveValid(move, isWhite));
+        }
+        return false;
+    }
+
 }

src/chess/King.java

@@ -25,22 +25,22 @@ public class King extends ChessPiece {
         ArrayList<Move> moves = new ArrayList<Move>();
         moves.addAll(super.getCardinalMoves(1));
         moves.addAll(super.getDiagonalMoves(1));
-        if (isFirstMove){
+        if (isFirstMove()){
             ChessPiece rook = null;
             // castling
             if (isWhite){
                 if ((rook = b.get(0, 0)) != null && checkIfRookValid(rook))
-                    moves.add(new Move(2, 0, Move.SpecialConditions.leftCastle));
+                    moves.add(b.checkIfMoveValid(new Move(2, 0, Move.SpecialConditions.leftCastle), isWhite));
                 if ((rook = b.get(b.size() - 1, 0)) != null && checkIfRookValid(rook))
-                    moves.add(new Move(b.size() - 2, 0, Move.SpecialConditions.rightCastle));
+                    moves.add(b.checkIfMoveValid(new Move(b.size() - 2, 0, Move.SpecialConditions.rightCastle), isWhite));
             } else {
                 if ((rook = b.get(0, b.size()-1)) != null && checkIfRookValid(rook))
-                    moves.add(new Move(2, b.size()-1, Move.SpecialConditions.leftCastle));
+                    moves.add(b.checkIfMoveValid(new Move(2, b.size()-1, Move.SpecialConditions.leftCastle), isWhite));
                 if ((rook = b.get(b.size() - 1, b.size()-1)) != null && checkIfRookValid(rook))
-                    moves.add(new Move(b.size() - 2, b.size()-1, Move.SpecialConditions.rightCastle));
+                    moves.add(b.checkIfMoveValid(new Move(b.size() - 2, b.size()-1, Move.SpecialConditions.rightCastle), isWhite));
             }
         }
-        return moves;
+        return prune(moves);
     }
 
     @Override
@@ -55,8 +55,9 @@ public class King extends ChessPiece {
     private void castleRight(){
         // casting has to move the rook on the right size of the king from white's perspective
         if (this.isWhite)
-            b.set(b.size()-3, 0, b.get(b.size()-1, 0));
+            b.movePiece(b.size() - 1, 0, b.size() - 3, 0);
         else
+            b.movePiece(b.size()-1, b.size()-1, b.size()-3, b.size()-1)
             b.set(b.size()-3, b.size()-1, b.get(b.size()-1, b.size()-1));
     }
 

src/chess/Knight.java

@@ -23,14 +23,14 @@ public class Knight extends ChessPiece {
     @Override
     public ArrayList<Move> getMoves() {
         ArrayList<Move> moves = new ArrayList<Move>();
-        moves.add(new Move(x + 2, y + 1));
-        moves.add(new Move(x + 2, y - 1));
-        moves.add(new Move(x - 2, y + 1));
-        moves.add(new Move(x - 2, y - 1));
-        moves.add(new Move(x - 1, y - 2));
-        moves.add(new Move(x + 1, y - 2));
-        moves.add(new Move(x - 1, y + 2));
-        moves.add(new Move(x + 1, y + 2));
-        return moves;
+        moves.add(b.checkIfMoveValid(new Move(x + 2, y + 1), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x + 2, y - 1), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x - 2, y + 1), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x - 2, y - 1), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x - 1, y - 2), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x + 1, y - 2), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x - 1, y + 2), isWhite));
+        moves.add(b.checkIfMoveValid(new Move(x + 1, y + 2), isWhite));
+        return prune(moves);
     }
 }

src/chess/Pawn.java

@@ -24,38 +24,45 @@ public class Pawn extends ChessPiece {
     public ArrayList<Move> getMoves() {
         ArrayList<Move> moves = new ArrayList<Move>();
         if (isWhite) {
-            moves.add(new Move(x, y + 1));
-            if (isFirstMove)
-                moves.add(new Move(x, y + 2));
+            moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x, y + 1)), isWhite));
+            if (isFirstMove())
+                moves.add(b.checkIfMoveValid(new Move(x, y + 2), isWhite));
         } else {
-            moves.add(new Move(x, y - 1));
-            if (isFirstMove)
-                moves.add(new Move(x, y - 2));
+            moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x, y - 1)), isWhite));
+            if (isFirstMove())
+                moves.add(b.checkIfMoveValid(new Move(x, y - 2), isWhite));
         }
         ChessPiece neighbour = null;
 
         if (isWhite){
             // En passant
             if ((neighbour = b.get(x-1, y)) != null && checkNeighbourEnPassant(neighbour))
-                moves.add(new Move(x-1, y + 1, Move.SpecialConditions.leftEnPassant));
+                moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x-1, y + 1, Move.SpecialConditions.leftEnPassant)), isWhite));
             // En passant
             if ((neighbour = b.get(x+1, y)) != null && checkNeighbourEnPassant(neighbour))
-                moves.add(new Move(x+1, + 1, Move.SpecialConditions.rightEnPassant));
+                moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x+1, + 1, Move.SpecialConditions.rightEnPassant)), isWhite));
         } else {
             // unfortunately have to flip the direction depending on player type
             // En passant
             if ((neighbour = b.get(x-1, y)) != null && checkNeighbourEnPassant(neighbour))
-                moves.add(new Move(x-1, y - 1, Move.SpecialConditions.leftEnPassant));
+                moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x-1, y - 1, Move.SpecialConditions.leftEnPassant)), isWhite));
             // En passant
             if ((neighbour = b.get(x+1, y)) != null && checkNeighbourEnPassant(neighbour))
-                moves.add(new Move(x+1, - 1, Move.SpecialConditions.rightEnPassant));
+                moves.add(b.checkIfMoveValid(pawnForwardMoveValid(new Move(x+1, - 1, Move.SpecialConditions.rightEnPassant)), isWhite));
         }
 
-        return moves;
+        return prune(moves);
+    }
+
+    private Move pawnForwardMoveValid(Move m){
+        // basically prevent a pawn from moving into the enemy head on.
+        if (b.get(m) != null)
+            return null;
+        return m;
     }
 
     private boolean checkNeighbourEnPassant(ChessPiece neighbour){
-        return neighbour instanceof Pawn && ((Pawn) neighbour).isFirstMove() && neighbour.isWhite != this.isWhite;
+        return neighbour instanceof Pawn && neighbour.isSecondMove() && neighbour.isWhite != this.isWhite;
     }
 
     @Override
@@ -69,15 +76,15 @@ public class Pawn extends ChessPiece {
 
     private void enPassantLeft(){
         if (isWhite)
-            b.set(x-1, y, null);
+            b.set(x, y-1, null);
         else
-            b.set(x+1, y, null);
+            b.set(x, y+1, null);
     }
 
     private void enPassantRight(){
         if (isWhite)
-            b.set(x+1, y, null);
+            System.out.println(b.set(x, y-1, null));
         else
-            b.set(x-1, y, null);
+            b.set(x, y-1, null);
     }
 }

src/chess/Queen.java

@@ -25,6 +25,6 @@ public class Queen extends ChessPiece {
         ArrayList<Move> moves = new ArrayList<Move>();
         moves.addAll(super.getCardinalMoves(b.size()));
         moves.addAll(super.getDiagonalMoves(b.size()));
-        return moves;
+        return prune(moves);
     }
 }

src/chess/Rook.java

@@ -20,6 +20,6 @@ public class Rook extends ChessPiece {
 
     @Override
     public ArrayList<Move> getMoves() {
-        return new ArrayList<Move>(super.getCardinalMoves(b.size()));
+        return prune(super.getCardinalMoves(b.size()));
     }
 }

src/ui/Display.java

@@ -51,7 +51,7 @@ public class Display extends JFrame implements MouseListener {
                 }
                 if (selectionPointX != -1 && selectionPointY != -1) {
                     int localPointX = (selectionPointX - xOffset) / width;
-                    int localPointY = (b.size() - 1) - ((selectionPointY - yOffset) / height);
+                    int localPointY = ((selectionPointY - yOffset) / height);
                     for (Move m : moves){
                         if (m.getX() == localPointX && m.getY() == localPointY){
                             b.movePiece(piece.getPosition(), new Move(localPointX, localPointY));
@@ -68,9 +68,10 @@ public class Display extends JFrame implements MouseListener {
         // handle user input (mouse clicking)
         if (selectionPointX != -1 && selectionPointY != -1){
             int localPointX = (selectionPointX - xOffset) / width;
-            int localPointY = (b.size()-1) - ((selectionPointY - yOffset) / height);
+            int localPointY = ((selectionPointY - yOffset) / height);
             var piece = b.get(localPointX, localPointY);
             if (piece != null) {
+                System.out.println(localPointX + " LL " + localPointY);
                 movingPointX = localPointX;
                 movingPointY = localPointY;
             }
@@ -80,7 +81,7 @@ public class Display extends JFrame implements MouseListener {
     }
 
     private void drawSelectionRect(Graphics g, Move m){
-        g.drawRect(xOffset + (m.getX() * width), yOffset + ((b.size()-1 - m.getY()) * height), width, height);
+        g.drawRect(xOffset + (m.getX() * width), yOffset + (m.getY() * height), width, height);
     }
 
     public boolean update(){