/*
 * Copyright (c) 2018. Developed by Hedgecode.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.hedgecode.chess.fen;

import java.util.Map;

import org.hedgecode.chess.Parsers;
import org.hedgecode.chess.position.Builder;
import org.hedgecode.chess.position.Color;
import org.hedgecode.chess.position.ColorPiece;
import org.hedgecode.chess.position.ParseException;
import org.hedgecode.chess.position.Position;
import org.hedgecode.chess.position.Square;

/**
 * Forsyth–Edwards Notation (FEN) builder.
 *
 * @author Dmitry Samoshin aka gotty
 */
public final class FENBuilder implements Builder {

    private static Builder _instance = new FENBuilder();

    private FENBuilder() {
    }

    @Override
    public String build(Position position) {
        return _build(
                position
        );
    }

    private String _build(Position position) {
        StringBuilder sb = new StringBuilder();
        sb.append(
                _buildPosition(position)
        ).append(
                FEN.FIELDS_SEP
        ).append(
                FEN.getColor(
                        position.getMove()
                )
        ).append(
                FEN.FIELDS_SEP
        ).append(
                FEN.getCastle(
                        position.getCastle(Color.WHITE),
                        position.getCastle(Color.BLACK)
                )
        ).append(
                FEN.FIELDS_SEP
        ).append(
                FEN.getEnPassant(
                        position.getEnPassant()
                )
        ).append(
                FEN.FIELDS_SEP
        ).append(
                position.getHalfMove()
        ).append(
                FEN.FIELDS_SEP
        ).append(
                position.getFullMove()
        );
        return sb.toString();
    }

    private String _buildPosition(Position position) {
        StringBuilder sb = new StringBuilder();
        Map<Square, ColorPiece> squares = position.getSquares();
        for (int i = Square.getSize() - 1; i >= 0; --i) {
            int empty = 0;
            for (int j = 0; j < Square.getSize(); ++j) {
                Square square = Square.getSquare(j, i);
                ColorPiece piece = squares.get(square);
                if (piece != null) {
                    if (empty > 0)
                        sb.append(empty);
                    sb.append(
                            FEN.getFenPiece(piece)
                    );
                    empty = 0;
                } else {
                    ++empty;
                }
            }
            if (empty > 0)
                sb.append(empty);
            if (i > 0)
                sb.append(FEN.LINE_SEP);
        }
        return sb.toString();
    }

    public static Builder getInstance() {
        return _instance;
    }


    public static void main(String[] args) throws ParseException {

        Position position = Parsers.FEN.parser().parse(
                "r7/7p/8/8/8/8/PPPPPP2/1N1Q2NR w KQkq a3 1 20"
        );
        System.out.println(
                getInstance().build(position)
        );

    }

}