class UpdateManager;

class UpdateReceiver
{
public:

    UpdateReceiver(std::shared_ptr<UpdateManager>& update_manager);

    virtual ~UpdateReceiver();

    virtual void Update(float dt) = 0;

private:

    std::weak_ptr<UpdateManager> m_updateManager;
};

class UpdateManager
{
public:

    void AddReceiver(UpdateReceiver& receiver)
    {
        std::cout << "Adding Receivern";
        m_updateReceivers.push_back(&receiver);
    }

    void RemoveReceiver(UpdateReceiver& receiver)
    {
        auto it = std::find(m_updateReceivers.begin(), m_updateReceivers.end(), &receiver);
        if (it != m_updateReceivers.end())
        {
            std::cout << "Removing Receivern";
            m_updateReceivers.erase(it);
        }
    }

    void Update()
    {
        for (auto& receiver : m_updateReceivers)
        {
            receiver->Update(1.f);
        }
    }

private:

    std::list<UpdateReceiver*> m_updateReceivers;
};


UpdateReceiver::UpdateReceiver(std::shared_ptr<UpdateManager>& update_manager)
    : m_updateManager(update_manager)
{
    update_manager->AddReceiver(*this);
}

UpdateReceiver::~UpdateReceiver()
{
    auto update_manager = m_updateManager.lock();
    if (update_manager)
    {
        update_manager->RemoveReceiver(*this);
    }
}

class Timer : public UpdateReceiver
{
public:

    Timer(std::shared_ptr<UpdateManager>& update_manager)
        : UpdateReceiver(update_manager)
    {}

    void Update(float dt) override
    {
        std::cout << "Updating Timern";
    }
};

int main()
{
    auto update_manager = std::make_shared<UpdateManager>();

    {
        Timer t{update_manager};

        update_manager->Update();
    }
}