Cars.java

package racingcar.domain;

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

public class Cars {
    private static final String DUPLICATE_NAME_ERROR = "자동차 이름은 중복될 수 없습니다.";
    
    private final List<Car> cars;
    
    public Cars(List<Car> cars) {
        validateCars(cars);
        this.cars = new ArrayList<>(cars);
    }
    
    private void validateCars(List<Car> cars) {
        if (cars == null || cars.isEmpty()) {
            throw new IllegalArgumentException("자동차 목록은 비어있을 수 없습니다.");
        }
        validateDuplicateNames(cars);
    }
    
    private void validateDuplicateNames(List<Car> cars) {
        List<String> names = cars.stream()
                .map(car -> car.getName().getName())
                .collect(Collectors.toList());
        
        long uniqueNameCount = names.stream()
                .distinct()
                .count();
        
        if (uniqueNameCount != names.size()) {
            throw new IllegalArgumentException(DUPLICATE_NAME_ERROR);
        }
    }
    
    public void moveAll() {
        for (Car car : cars) {
            car.move();
        }
    }
    
    public List<Car> getCars() {
        return Collections.unmodifiableList(cars);
    }
    
    public List<Car> getWinners() {
        int maxPosition = getMaxPosition();
        return cars.stream()
                .filter(car -> car.isAtPosition(maxPosition))
                .collect(Collectors.toList());
    }
    
    private int getMaxPosition() {
        return cars.stream()
                .mapToInt(Car::getPosition)
                .max()
                .orElse(0);
    }
    
    public int size() {
        return cars.size();
    }
    
    public Car get(int index) {
        return cars.get(index);
    }
    
    @Override
    public String toString() {
        return cars.stream()
                .map(Car::toString)
                .collect(Collectors.joining("\n"));
    }
}