package backend;

import java.util.HashSet;
import java.util.Set;

public class CheckKing {

    // 1. Check if the king of the given color is under attack
    public static boolean isKingInCheck(Board board, boolean white) {
        Piece[][] grid = board.getBoardMatrix();
        Piece king = null;

        // Find the king
        for (int y = 0; y < board.getHeight(); y++) {
            for (int x = 0; x < board.getWidth(); x++) {
                Piece piece = grid[y][x];
                if (piece != null && piece.isWhite() == white && piece.getType() == PieceType.King) {
                    king = piece;
                    break;
                }
            }
        }

        if (king == null) return false;

        int kingX = king.getX();
        int kingY = king.getY();

        // Check if any opposing piece can move to the king’s square
        for (Piece[] row : grid) {
            for (Piece p : row) {
                if (p != null && p.isWhite() != white) {
                    Set<String> moves = board.getValidMoves(p, true); // skip validation
                    if (moves.contains(kingX + "," + kingY)) {
                        return true;
                    }
                }
            }
        }

        return false;
    }

    // 2. Filter out any moves that would leave the king in check
    public static Set<String> filterLegalMoves(Board board, Piece piece, Set<String> candidateMoves) {
        Set<String> legalMoves = new HashSet<>();

        for (String move : candidateMoves) {
            String[] parts = move.split(",");
            int toX = Integer.parseInt(parts[0]);
            int toY = Integer.parseInt(parts[1]);

            // Create a simulated board to test the move
            Board copy = new Board(board);
            copy.movePiece(piece.getX(), piece.getY(), toX, toY);

            if (!isKingInCheck(copy, piece.isWhite())) {
                legalMoves.add(move);
            }
        }

        return legalMoves;
    }
}