import java.util.Random;

public class EntityWithRollers<T extends EntityTracktor, U extends IDrawningRollers> {
    static Random rnd = new Random();
    private Object[] entities;
    public int entitiesCount = 0;
    private Object[] rollers;
    public int rollersCount = 0;

    public EntityWithRollers(int count) {
        //new T[count] не работает "Type parameter 'T' cannot be instantiated directly"
        entities = new Object[count];
        //new U[count] не работает "Type parameter 'U' cannot be instantiated directly"
        rollers = new Object[count];
    }

    public boolean add(T entity) {
        if (entitiesCount >= entities.length) {
        return false;
    }
        entities[entitiesCount++] = entity;
        return true;
    }

    public boolean add(U roller) {
        if (rollersCount >= rollers.length) {
        return false;
    }
        rollers[rollersCount++] = roller;
        return true;
    }

    public IDrawningObject constructArtillery() {
        if (entitiesCount == 0 || rollersCount == 0) {
            return null;
        }
        EntityTracktor entity = (EntityTracktor) entities[rnd.nextInt(0, entitiesCount)];
        IDrawningRollers roller = (IDrawningRollers) rollers[rnd.nextInt(0, rollersCount)];

        if (entity instanceof EntityTrackedVehicle advancedEntity) {
            return new DrawningObjectExcavator(new DrawningTrackedVehicle(advancedEntity, roller));
        }
        return new DrawningObjectExcavator(new DrawningTracktor(entity, roller));
    }
}