undo

src/backend/Board.java

@@ -352,7 +352,26 @@ public class Board {
 	}
 
 	public void undoLastMove() {
-	    
+		if (moveHistory.isEmpty()) return;
+
+	    Move lastMove = moveHistory.remove(moveHistory.size() - 1);
+	    Piece movedPiece = lastMove.getPieceMoved();
+
+	    // Move the piece back to its original position
+	    movedPiece.setPosition(lastMove.getFromX(), lastMove.getFromY());
+
+	    // Restore the captured piece if any
+	    if (lastMove.getPieceCaptured() != null) {
+	        pieces.add(lastMove.getPieceCaptured());
+	    }
+
+	    // Switch turn and decrease turn count
+	    turnWhite = !turnWhite;
+	    turnNumber--;
+
+	    // Clear selection and highlights
+	    selected = null;
+	    highlighted.clear();
 	}