Answer.java

package baseball.model;

public class Answer {
    private final BaseballNumber number;

    private Answer(BaseballNumber number) {
        this.number = number;
    }

    public static Answer random() {
        return new Answer(BaseballNumber.random());
    }

    public static Answer from(BaseballNumber number) {
        return new Answer(number);
    }

    public Score compare(BaseballNumber guess) {
        int strikes = countStrikes(guess);
        int balls = countBalls(guess);

        return Score.of(strikes, balls, guess.size());
    }

    private int countStrikes(BaseballNumber guess) {
        int count = 0;
        for (int i = 0; i < number.size(); i++) {
            if (isStrike(i, guess.digitAt(i))) {
                count++;
            }
        }
        return count;
    }

    private int countBalls(BaseballNumber guess) {
        int count = 0;
        for (int i = 0; i < number.size(); i++) {
            if (isBall(i, guess.digitAt(i))) {
                count++;
            }
        }
        return count;
    }

    private boolean isStrike(int index, int digit) {
        return number.digitAt(index) == digit;
    }

    private boolean isBall(int index, int digit) {
        return !isStrike(index, digit) && number.contains(digit);
    }
}