Fix blocking checkmate

src/Board.java

@@ -30,9 +30,11 @@ public class Board {
     ArrayList<Move> legalMoves = null;
     Stack<Move> moveHistory;
     public boolean isGameOver;
+    public boolean isStalemate;
     public boolean victor;
     Image youWin;
     Image youLose;
+    Image stalemate;
 
     public Board() {
         moveHistory = new Stack<>();
@@ -41,6 +43,7 @@ public class Board {
         panel = new DrawingPanel(DIMENSION, DIMENSION);
         youWin = panel.loadImage("you-win.png");
         youLose = panel.loadImage("you-lose.png");
+        stalemate = panel.loadImage("stalemate.png");
         graphics = panel.getGraphics();
 
         // Connect up event handlers
@@ -160,6 +163,7 @@ public class Board {
     void handleMouseDown(int x, int y) {
         if (isGameOver) {
             isGameOver = false;
+            isStalemate = false;
             setup();
             return;
         }
@@ -223,14 +227,14 @@ public class Board {
         if (inCheck) {
             isGameOver = true;
             for (Move move : getAllLegalMoves(!movedPiece.black)) {
-                move(move);
                 if (!oppositeKing.isInCheck(move, this)) {
                     isGameOver = false;
-                    undoMove();
                     break;
                 }
-                undoMove();
             }
+        } else if (getAllLegalMoves(movedPiece.black).isEmpty()) {
+            isGameOver = true;
+            isStalemate = true;
         }
         victor = movedPiece.black;
     }
@@ -284,7 +288,7 @@ public class Board {
 
         // Draw game over text
         if (isGameOver) {
-            graphics.drawImage(victor ? youLose : youWin, 0, 0, panel);
+            graphics.drawImage(isStalemate ? stalemate : (victor ? youLose : youWin), 0, 0, panel);
         }
     }
 

src/ChessAI.java

@@ -1,3 +1,6 @@
+import java.util.ArrayList;
+import java.util.Collections;
+
 public class ChessAI {
     private static final int MAX_DEPTH = 3;
 
@@ -5,7 +8,9 @@ public class ChessAI {
         int bestScore = Integer.MIN_VALUE;
         Move bestMove = null;
 
-        for (Move move : board.getAllLegalMoves(true)) {
+        ArrayList<Move> legalMoves = board.getAllLegalMoves(true);
+        Collections.shuffle(legalMoves);
+        for (Move move : legalMoves) {
             board.move(move);
             int score = minimax(board, MAX_DEPTH, Integer.MIN_VALUE, Integer.MAX_VALUE, false);
             board.undoMove();

src/Pawn.java

@@ -13,9 +13,7 @@ public class Pawn extends Piece {
         ArrayList<Move> possibleMoves = new ArrayList<>();
         if (this.black) {
             if (board.get(position.x, position.y + 1) == null) {
-                Move oneForward = new Move(position, new BoardCoordinate(position.x, position.y + 1));
+                possibleMoves.add(new Move(position, new BoardCoordinate(position.x, position.y + 1)));
-                oneForward.isPromotion = position.y + 1 == Board.BOARD_SIZE - 1;
-                possibleMoves.add(oneForward);
                 if (!moved && board.get(position.x, position.y + 2) == null) {
                     possibleMoves.add(new Move(position, new BoardCoordinate(position.x, position.y + 2)));
                 }
@@ -26,12 +24,10 @@ public class Pawn extends Piece {
             if (board.get(position.x + 1, position.y + 1) != null) {
                 possibleMoves.add(new Move(position, new BoardCoordinate(position.x + 1,position.y + 1)));
             }
-
+            for (Move move : possibleMoves) move.isPromotion = position.y + 1 == 0;
         } else {
             if (board.get(position.x, position.y - 1) == null) {
-                Move oneForward = new Move(position, new BoardCoordinate(position.x, position.y - 1));
+                possibleMoves.add(new Move(position, new BoardCoordinate(position.x, position.y - 1)));
-                oneForward.isPromotion = position.y - 1 == 0;
-                possibleMoves.add(oneForward);
                 if (!moved && board.get(position.x, position.y - 2) == null) {
                     possibleMoves.add(new Move(position, new BoardCoordinate(position.x, position.y - 2)));
                 }
@@ -42,6 +38,7 @@ public class Pawn extends Piece {
             if (board.get(position.x + 1, position.y - 1) != null) {
                 possibleMoves.add(new Move(position, new BoardCoordinate(position.x + 1,position.y - 1)));
             }
+            for (Move move : possibleMoves) move.isPromotion = position.y - 1 == 0;
         }
         return possibleMoves;
     }

stalemate.svg

@@ -0,0 +1,117 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="512mm"
+   height="512mm"
+   viewBox="0 0 512 512"
+   version="1.1"
+   id="svg5"
+   sodipodi:docname="stalemate.svg"
+   inkscape:export-filename="stalemate.png"
+   inkscape:export-xdpi="25.4"
+   inkscape:export-ydpi="25.4"
+   inkscape:version="1.2.2 (b0a8486541, 2022-12-01)"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg">
+  <sodipodi:namedview
+     id="namedview7"
+     pagecolor="#ffffff"
+     bordercolor="#000000"
+     borderopacity="0.25"
+     inkscape:showpageshadow="2"
+     inkscape:pageopacity="0.0"
+     inkscape:pagecheckerboard="0"
+     inkscape:deskcolor="#d1d1d1"
+     inkscape:document-units="mm"
+     showgrid="false"
+     inkscape:zoom="0.3901936"
+     inkscape:cx="492.06342"
+     inkscape:cy="1009.7551"
+     inkscape:window-width="1920"
+     inkscape:window-height="1048"
+     inkscape:window-x="1920"
+     inkscape:window-y="32"
+     inkscape:window-maximized="1"
+     inkscape:current-layer="layer1" />
+  <defs
+     id="defs2">
+    <rect
+       x="380.73235"
+       y="551.6332"
+       width="1925.2562"
+       height="945.95678"
+       id="rect952" />
+    <filter
+       style="color-interpolation-filters:sRGB;"
+       inkscape:label="Drop Shadow"
+       id="filter1272"
+       x="-0.020339003"
+       y="0"
+       width="1.020339"
+       height="1.1324139">
+      <feFlood
+         flood-opacity="0.498039"
+         flood-color="rgb(0,0,0)"
+         result="flood"
+         id="feFlood1262" />
+      <feComposite
+         in="flood"
+         in2="SourceGraphic"
+         operator="in"
+         result="composite1"
+         id="feComposite1264" />
+      <feGaussianBlur
+         in="composite1"
+         stdDeviation="0"
+         result="blur"
+         id="feGaussianBlur1266" />
+      <feOffset
+         dx="-32"
+         dy="32"
+         result="offset"
+         id="feOffset1268" />
+      <feComposite
+         in="SourceGraphic"
+         in2="offset"
+         operator="over"
+         result="composite2"
+         id="feComposite1270" />
+    </filter>
+  </defs>
+  <g
+     inkscape:label="Layer 1"
+     inkscape:groupmode="layer"
+     id="layer1">
+    <rect
+       style="fill:#333333;stroke-width:0.264583;fill-opacity:0.5"
+       id="rect111"
+       width="512"
+       height="512"
+       x="0"
+       y="0" />
+    <text
+       xml:space="preserve"
+       transform="matrix(0.26458333,0,0,0.26458333,-42.254641,69.177459)"
+       id="text950"
+       style="font-size:256px;white-space:pre;shape-inside:url(#rect952);display:inline;fill:#3d3d3d;fill-opacity:1;filter:url(#filter1272)"><tspan
+         x="380.73242"
+         y="782.22594"
+         id="tspan1879"><tspan
+           style="font-weight:bold;font-family:Arimo;-inkscape-font-specification:'Arimo Bold';fill:#ffffff"
+           id="tspan1877">STALEMATE</tspan></tspan></text>
+    <text
+       xml:space="preserve"
+       style="font-style:normal;font-variant:normal;font-weight:bold;font-stretch:normal;font-size:33.8667px;font-family:Arimo;-inkscape-font-specification:'Arimo Bold';fill:#ffffff;fill-opacity:0.75;stroke-width:0.264583"
+       x="110.52037"
+       y="328.68213"
+       id="text1451"><tspan
+         sodipodi:role="line"
+         id="tspan1449"
+         style="font-size:33.8667px;fill:#ffffff;fill-opacity:0.75;stroke-width:0.264583"
+         x="110.52037"
+         y="328.68213">click to play again</tspan></text>
+  </g>
+</svg>

you-lose.svg

@@ -8,7 +8,7 @@
    version="1.1"
    id="svg5"
    sodipodi:docname="you-lose.svg"
-   inkscape:export-filename="you-win.png"
+   inkscape:export-filename="you-lose.png"
    inkscape:export-xdpi="25.4"
    inkscape:export-ydpi="25.4"
    inkscape:version="1.2.2 (b0a8486541, 2022-12-01)"
@@ -28,8 +28,8 @@
      inkscape:document-units="mm"
      showgrid="false"
      inkscape:zoom="0.3901936"
-     inkscape:cx="1232.7214"
+     inkscape:cx="786.78891"
-     inkscape:cy="1014.8808"
+     inkscape:cy="981.56402"
      inkscape:window-width="1920"
      inkscape:window-height="1048"
      inkscape:window-x="1920"
@@ -99,9 +99,9 @@
        style="font-size:341.333px;white-space:pre;shape-inside:url(#rect952);display:inline;fill:#3d3d3d;fill-opacity:1;filter:url(#filter1272)"><tspan
          x="380.73242"
          y="859.09003"
-         id="tspan1803"><tspan
+         id="tspan1823"><tspan
            style="font-weight:bold;font-family:Arimo;-inkscape-font-specification:'Arimo Bold';fill:#ffffff"
-           id="tspan1801">YOU LOSE</tspan></tspan></text>
+           id="tspan1821">YOU LOSE</tspan></tspan></text>
     <text
        xml:space="preserve"
        style="font-style:normal;font-variant:normal;font-weight:bold;font-stretch:normal;font-size:33.8667px;font-family:Arimo;-inkscape-font-specification:'Arimo Bold';fill:#ffffff;fill-opacity:0.75;stroke-width:0.264583"