Match.java

package nextstep.ladder.domain;

import java.util.LinkedHashMap;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Match {

    private static final int BEGIN_IDX = 0;

    private final InputOutput inputOutput;
    private final Ladder ladder;

    public Match(InputOutput inputOutput, Ladder ladder) {
        this.inputOutput = inputOutput;
        this.ladder = ladder;
    }

    public Match(Ladder ladder) {
        this(null, ladder);
    }

    public Result makeResult() {
        List<Person> people = inputOutput.people().value();
        List<ExecuteResult> executeResults = inputOutput.executeResults().value();

        return new Result(IntStream.range(BEGIN_IDX, people.size())
                .boxed()
                .collect(Collectors.toMap(i -> people.get(i).name(), i -> executeResults.get(findOutputIdx(i)).name(),
                        (v1, v2) -> v1, LinkedHashMap::new)));
    }

    int findOutputIdx(int startIdx) {
        int currentIdx = startIdx * 2;
        String[][] ladder = this.ladder.result();
        int rowCount = ladder.length;
        int columnLength = ladder[BEGIN_IDX].length;

        currentIdx = IntStream.range(BEGIN_IDX, rowCount)
                .reduce(currentIdx, (idx, i) -> {
                    String[] row = ladder[i];
                    if (isMovableToLeft(idx, row)) {
                        return idx - 2;
                    }
                    if (isMovableToRight(idx, row, columnLength)) {
                        return idx + 2;
                    }
                    return idx;
                });
        return currentIdx / 2;
    }

    private boolean isMovableToLeft(int idx, String[] row) {
        return idx > BEGIN_IDX && "h".equals(row[idx - 1]);
    }

    private boolean isMovableToRight(int idx, String[] row, int columnLength) {
        return idx < columnLength - 1 && "h".equals(row[idx + 1]);
    }
}