Cars.java

package racingcar.domain;

import racingcar.util.RandomNumberGenerator;

import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

public class Cars {
    private static final int RANDOM_MIN = 0;
    private static final int RANDOM_MAX = 9;

    private final List<Car> cars;

    public Cars(List<Car> cars) {
        validateNoDuplicateNames(cars);
        this.cars = List.copyOf(cars);
    }

    private void validateNoDuplicateNames(List<Car> cars) {
        long uniqueNameCount = cars.stream()
                .map(Car::getName)
                .distinct()
                .count();

        if (uniqueNameCount != cars.size()) {
            throw new IllegalArgumentException("자동차 이름은 중복될 수 없습니다.");
        }
    }

    public void moveAll() {
        for (Car car : cars) {
            int random = RandomNumberGenerator.generateInRange(RANDOM_MIN, RANDOM_MAX);
            car.move(random);
        }
    }

    public List<Car> getCars() {
        return Collections.unmodifiableList(cars);
    }

    public List<Car> getWinners() {
        int maxPosition = findMaxPosition();
        return findCarsWithPosition(maxPosition);
    }

    private int findMaxPosition() {
        return cars.stream()
                .mapToInt(Car::getPosition)
                .max()
                .orElse(0);
    }

    private List<Car> findCarsWithPosition(int position) {
        return cars.stream()
                .filter(car -> car.getPosition() == position)
                .toList();
    }
}