import static java.lang.Integer.signum;
import static java.lang.Math.abs;

class Piece {
    Kind kind;
    Color color;
    Board board;
    int row;
    int col;

    Piece(Kind kind, Color color, Board board, int row, int col) {
        if (row < 1 || row > 8 || col < 1 || col > 8)
            throw new IllegalArgumentException("Invalid pos " + row + "/" + col);
        this.kind = kind;
        this.color = color;
        this.board = board;
        this.row = row;
        this.col = col;
        board.add(this);
    }

    char charRep() {
        switch (kind) {
            case QUEEN:
                return queenCharRep();
            case KNIGHT:
                return knightCharRep();
        }
        throw new IllegalArgumentException("Unknown piece " + kind);
    }

    String showPiece() {
        switch (kind) {
            case QUEEN:
                return queenShowPiece();
            case KNIGHT:
                return knightShowPiece();
        }
        throw new IllegalArgumentException("Unknown piece " + kind);
    }

    boolean canCapture(Piece other) {
        switch (kind) {
            case QUEEN:
                return queenCanCapture(other);
            case KNIGHT:
                return knightCanCapture(other);
        }
        throw new IllegalArgumentException("Unknown piece " + kind);
    }

    char queenCharRep() {
        if (color == Color.WHITE)
            return 'q';
        else
            return 'Q';
    }

    char knightCharRep() {
        if (color == Color.WHITE)
            return 'n';
        else
            return 'N';
    }

    String queenShowPiece() {
        return "" + color.toString().toLowerCase() + " queen at (" + row + ", " + col + ")";
    }

    String knightShowPiece() {
        return "" + color.toString().toLowerCase() + " knight at (" + row + ", " + col + ")";
    }

    boolean queenCanCapture(Piece other) {
        if (board != other.board || color == other.color)
            return false;
        if (other.row != row &&
            other.col != col &&
            abs(other.row - row) != abs(other.col - col))
            return false;
        final int dr = signum(other.row - row);
        final int dc = signum(other.col - col);
        int r = row + dr;
        int c = col + dc;
        while (r != other.row || c != other.col) {
            if (board.pieceAt(r, c) != null) return false;
            r += dr;
            c += dc;
        }
        return true;
    }

    boolean knightCanCapture(Piece other) {
        if (board != other.board || color == other.color)
            return false;
        final int dr = abs(row - other.row);
        final int dc = abs(col - other.col);
        return dr == 2 && dc == 1 || dr == 1 && dc == 2;
    }
}