C_subscription.hpp

/*
 * Copyright 2026 Guillaume Guillet
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef _FGE_C_SUBSCRIPTION_HPP_INCLUDED
#define _FGE_C_SUBSCRIPTION_HPP_INCLUDED
 
#include "FastEngine/fge_extern.hpp"
#include <cstdint>
#include <unordered_map>
#include <unordered_set>
 
namespace fge
{
 
class Subscriber;
 
class BaseSubscription
{
public:
    using SubscriberCount = unsigned int;
 
    BaseSubscription() = default;
    virtual ~BaseSubscription() = default;
 
protected:
    virtual void onDetach(fge::Subscriber* subscriber) = 0;

    virtual void detachAll() = 0;

    virtual bool detach(fge::Subscriber* subscriber) = 0;
    virtual SubscriberCount detachOnce(fge::Subscriber* subscriber) = 0;

    virtual SubscriberCount attach(fge::Subscriber* subscriber) = 0;

    [[nodiscard]] virtual SubscriberCount getCount(fge::Subscriber* subscriber) const = 0;
 
private:
    virtual void detachSilent(fge::Subscriber* subscriber) = 0;
 
    friend class fge::Subscriber;
};

class FGE_API Subscription : public BaseSubscription
{
public:
    Subscription() = default;

    Subscription([[maybe_unused]] fge::Subscription const& r) {}
    Subscription(fge::Subscription&& r) noexcept;

    inline ~Subscription() override { this->Subscription::detachAll(); }

    fge::Subscription& operator=([[maybe_unused]] fge::Subscription const& r) { return *this; }
    fge::Subscription& operator=(fge::Subscription&& r) noexcept;
 
protected:
    void detachAll() override;
    bool detach(fge::Subscriber* subscriber) override;
    SubscriberCount detachOnce(fge::Subscriber* subscriber) override;
 
    SubscriberCount attach(fge::Subscriber* subscriber) override;
 
    SubscriberCount getCount(fge::Subscriber* subscriber) const override;
 
private:
    using SubscriptionDataType = std::unordered_map<fge::Subscriber*, SubscriberCount>;
 
    void detachSilent(fge::Subscriber* subscriber) override;
 
    SubscriptionDataType g_subData;
};

class FGE_API UniqueSubscription : public BaseSubscription
{
public:
    UniqueSubscription() = default;

    UniqueSubscription([[maybe_unused]] fge::UniqueSubscription const& r) {}
    UniqueSubscription(fge::UniqueSubscription&& r) noexcept;

    virtual inline ~UniqueSubscription() override { this->UniqueSubscription::detachAll(); }

    fge::UniqueSubscription& operator=([[maybe_unused]] fge::UniqueSubscription const& r) { return *this; };
    fge::UniqueSubscription& operator=(fge::UniqueSubscription&& r) noexcept;
 
protected:
    void detachAll() override;
    bool detach(fge::Subscriber* subscriber) override;
    SubscriberCount detachOnce(fge::Subscriber* subscriber) override;
 
    SubscriberCount attach(fge::Subscriber* subscriber) override;
 
    SubscriberCount getCount(fge::Subscriber* subscriber) const override;
 
private:
    void detachSilent(fge::Subscriber* subscriber) override;
 
    fge::Subscriber* g_subscriber = nullptr;
};

class FGE_API Subscriber
{
public:
    Subscriber() = default;

    Subscriber([[maybe_unused]] fge::Subscriber const& n) {};
    Subscriber(fge::Subscriber&& n) noexcept = delete;

    virtual inline ~Subscriber() { this->detachAll(); };

    fge::Subscriber& operator=([[maybe_unused]] fge::Subscriber const& n) { return *this; };
    fge::Subscriber& operator=(fge::Subscriber&& n) noexcept = delete;

    void detachAll();
    void detach(fge::BaseSubscription* subscription);
 
protected:
    virtual void onDetach([[maybe_unused]] fge::BaseSubscription* subscription) {}
 
private:
    using SubscriberDataType = std::unordered_set<fge::BaseSubscription*>;

    void detachSilent(fge::BaseSubscription* subscription);
    void attachSilent(fge::BaseSubscription* subscription);
 
    SubscriberDataType g_subData;
    friend class fge::Subscription;
    friend class fge::UniqueSubscription;
};
 
} // namespace fge
 
#endif // _FGE_C_SUBSCRIPTION_HPP_INCLUDED