ischeckmate implemnted

src/backend/Board.java

@@ -756,5 +756,31 @@ public class Board {
 	    // Replace highlights with filtered version
 	    highlightedSquares = newHighlights;
 	}
+	
+	public boolean isCheckmate(boolean isWhite) {
+		if (!isKingInCheck(isWhite)) {
+		return false; // Not in check, so not checkmate
+		}
+
+		// Check if ANY legal move can get the king out of check
+		for (Piece piece : getPieces()) {
+		if (piece.isWhite() == isWhite) {
+		ArrayList<Move> legalMoves = getLegalMoves(piece);
+
+		for (Move move : legalMoves) {
+		// Simulate move
+		Board simulatedBoard = new Board(this.toFileRep());
+		simulatedBoard.playMove(move);
+
+		// If king is not in check after this move, it's not checkmate
+		if (!simulatedBoard.isKingInCheck(isWhite)) {
+		return false;
+		}
+		}
+		}
+		}
+
+		return true; // No legal move prevents check => checkmate
+		}
 
 }