class Manager
{
private:
    std::vector<std::unique_ptr<Entity>> entities; //list of entities
    std::array<std::vector<Entity *>, maxGroups> groupedEntities; //group of entities

public:

    void update()
    {
        for(auto &e : entities) e->update();
    }

    void draw()
    {
        for(auto &e : entities) e->draw();
    }

    void refresh()
    {
        for(auto i(0u); i < maxGroups; i++)
        {
            auto &v(groupedEntities[i]);
            v.erase(
                std::remove_if(std::begin(v), std::end(v), [i](Entity *mEntity)
                               {
                                   return !mEntity->isActive() || !mEntity->hasGroup(i);
                               }), std::end(v));
        }



        entities.erase(std::remove_if(std::begin(entities), std::end(entities),
                                      [](const std::unique_ptr<Entity> &mEntity)
                                      {
                                          return !mEntity->isActive();
                                      }),
                       std::end(entities));
    }

    //Adding entities to groups
    void AddToGroup(Entity *mEntity, Group mGroup)
    {
        groupedEntities[mGroup].emplace_back(mEntity);
    }
    //fetching entity group
    std::vector<Entity *> &getGroup(Group mGroup)
    {
        return groupedEntities[mGroup];
    }

    //Adding an entity
    Entity &addentity()
    {
        Entity *e = new Entity(*this);
        std::unique_ptr<Entity> uPtr{ e };
        entities.emplace_back(std::move(uPtr));
        return *e;
    }
};