Updated the message of the winner.

src/backend/Board.java

@@ -11,7 +11,8 @@ public class Board {
 	private boolean turnWhite=true; // True if it's White's turn, False if it's Black's turn
 	private ArrayList<int[]> highlightedPositions = new ArrayList<>(); // List containing all board positions
 	private ArrayList<MoveRecord> moveHistory = new ArrayList<>(); // List to store move history
-	
+	private String winnerMessage;
+	private boolean suppressCheckmateCheck = false;
 	private boolean inBounds(int x, int y) {
 		// Verify the bounds of the board
 	    return x >= 0 && y >= 0 && x < col && y < line;
@@ -452,8 +453,63 @@ public class Board {
 				//Clear selection/highlight
 				this.selectedPosition = null;
 				this.highlightedPositions.clear();
+				
+				if (!suppressCheckmateCheck && isCheckmate(!turnWhite)) {
+					winnerMessage = turnWhite ? "White is the winner" : "Black is the winner";
+				}
 		
 
 	}
+	public boolean isKingInCheck(boolean kingIsWhite) {
+		int kingX = -1, kingY = -1;
+		
+		//Find the king
+		for (Piece p : getPieces()) {
+			if (p.getType() == PieceType.King && p.isWhite() == kingIsWhite) {
+				kingX = p.getX();
+				kingY = p.getY();
+				break;
+			}
+		}
+		if (kingX == -1)
+			return false;
+		for (Piece p : getPieces()) {
+			if (p.isWhite() != kingIsWhite) {
+				for (int[] m : getValidMoves(p)) {
+					if (m[0] == kingX && m[1] == kingY) {
+						return true; //King in check
+					}
+				}
+			}
+		}
+		return false;
+	}
+	public boolean isCheckmate(boolean playerWhite) {
+		if (!isKingInCheck(playerWhite))
+			return false;
+		for (Piece p : getPieces()) {
+			if (p.isWhite() == playerWhite) {
+				for (int[] move : getValidMoves(p)) {
+					//simulate the move
+					Board copy = new Board(this);
+					copy.suppressCheckmateCheck = true;
+					Piece simPiece = copy.board[p.getY()][p.getX()];
+					Move m = new Move(simPiece, move[0], move[1]);
+					copy.playMove(m);
+					
+					if (!copy.isKingInCheck(playerWhite)) {
+						return false;
+					}
+				}
+			}
+		}
+		return true;
+	}
+	public String getWinnerMessage() {
+		return winnerMessage;
+	}
+	public void setWinnerMessage(String message) {
+		this.winnerMessage = message;
+	}
 
 }

src/backend/Game.java

@@ -49,7 +49,22 @@ public class Game extends Thread {
 
 	private void aiPlayerTurn() {
 		if(isAITurn()) {
-			board.playMove(aiPlayer.computeBestMove(new Board(board)));
+			Move move = aiPlayer.computeBestMove(new Board(board));
+			
+			if (move != null) {
+				board.playMove(move);
+			}
+			else {
+				if (board.isKingInCheck(board.isTurnWhite())) {
+					System.out.println((board.isTurnWhite() ? "White" : "Black") + "is checkmated!");
+					board.setWinnerMessage((!board.isTurnWhite() ? "White" : "Black") + "wins by checkmate!");
+					
+				}
+				else {
+					System.out.println("It's a draw");
+					board.setWinnerMessage("Draw!");
+				}
+			}
 		}
 	}