C_callback.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_CALLBACKHANDLER_HPP_INCLUDED
#define _FGE_C_CALLBACKHANDLER_HPP_INCLUDED
 
#include "FastEngine/C_subscription.hpp"
#include <memory>
#include <mutex>
#include <vector>
 
namespace fge
{

template<class TReturn, class... Types>
class CallbackBase
{
public:
    virtual ~CallbackBase() = default;
 
    virtual TReturn call(Types... args) = 0;
    virtual bool check(void* ptr) = 0;
};

template<class TReturn, class... Types>
class CallbackFunctor : public fge::CallbackBase<TReturn, Types...>
{
public:
    using CallbackFunction = TReturn (*)(Types... args);

    explicit CallbackFunctor(CallbackFunction func);
    ~CallbackFunctor() override = default;

    TReturn call(Types... args) override;
    inline bool check(void* ptr) override;
 
protected:
    CallbackFunction g_function;
};

template<class TReturn, class... Types>
class CallbackLambda : public fge::CallbackBase<TReturn, Types...>
{
public:
    template<typename TLambda>
    explicit CallbackLambda(TLambda const& lambda);
    ~CallbackLambda() override;

    TReturn call(Types... args) override;
    inline bool check(void* ptr) override;
 
protected:
    void* g_lambda;
    TReturn (*g_executeLambda)(void*, Types...);
    void (*g_deleteLambda)(void*);
};

template<class TReturn, class TObject, class... Types>
class CallbackObjectFunctor : public fge::CallbackBase<TReturn, Types...>
{
public:
    using CallbackFunctionObject = TReturn (TObject::*)(Types... args);

    CallbackObjectFunctor(CallbackFunctionObject func, TObject* object);
    ~CallbackObjectFunctor() override = default;

    TReturn call(Types... args) override;
    inline bool check(void* ptr) override;
 
protected:
    CallbackFunctionObject g_functionObj;
    TObject* g_object;
};
 
template<class TReturn, class... Types>
using CalleeUniquePtr = std::unique_ptr<fge::CallbackBase<TReturn, Types...>>;
template<class TReturn, class... Types>
using CalleeSharedPtr = std::shared_ptr<fge::CallbackBase<TReturn, Types...>>;

template<class TReturn, class TCalleePtr, class... Types>
struct CallbackStaticHelpers
{
    using CalleePtr = TCalleePtr;

    [[nodiscard]] inline static CalleePtr
    newFunctor(typename fge::CallbackFunctor<TReturn, Types...>::CallbackFunction func)
    {
        return CalleePtr{new fge::CallbackFunctor<TReturn, Types...>(func)};
    }

    template<typename TLambda>
    [[nodiscard]] inline static CalleePtr newLambda(TLambda const& lambda)
    {
        return CalleePtr{new fge::CallbackLambda<TReturn, Types...>(lambda)};
    }

    template<class TObject>
    [[nodiscard]] inline static CalleePtr
    newObjectFunctor(typename fge::CallbackObjectFunctor<TReturn, TObject, Types...>::CallbackFunctionObject func,
                     TObject* object)
    {
        return CalleePtr{new fge::CallbackObjectFunctor<TReturn, TObject, Types...>(func, object)};
    }
};

template<class... Types>
class CallbackHandler : public fge::Subscription
{
public:
    using CalleePtr = CalleeUniquePtr<void, Types...>;
    using StaticHelpers = CallbackStaticHelpers<void, CalleePtr, Types...>;
 
    CallbackHandler() = default;
    ~CallbackHandler() override = default;

    CallbackHandler([[maybe_unused]] fge::CallbackHandler<Types...> const& n) :
            fge::Subscription() {};

    CallbackHandler(fge::CallbackHandler<Types...>&& n) = delete;

    fge::CallbackHandler<Types...>& operator=([[maybe_unused]] fge::CallbackHandler<Types...> const& n)
    {
        return *this;
    };

    fge::CallbackHandler<Types...>& operator=(fge::CallbackHandler<Types...>&& n) = delete;

    inline void clear();

    inline fge::CallbackBase<void, Types...>* add(CalleePtr&& callback, fge::Subscriber* subscriber = nullptr);

    inline fge::CallbackFunctor<void, Types...>*
    addFunctor(typename fge::CallbackFunctor<void, Types...>::CallbackFunction func,
               fge::Subscriber* subscriber = nullptr);
    template<typename TLambda>
    inline fge::CallbackLambda<void, Types...>* addLambda(TLambda const& lambda, fge::Subscriber* subscriber = nullptr);
    template<class TObject>
    inline fge::CallbackObjectFunctor<void, TObject, Types...>*
    addObjectFunctor(typename fge::CallbackObjectFunctor<void, TObject, Types...>::CallbackFunctionObject func,
                     TObject* object,
                     Subscriber* subscriber = nullptr);

    void delPtr(void* ptr);
    void delSub(fge::Subscriber* subscriber);
    void del(fge::CallbackBase<void, Types...>* callback);

    void call(Types... args);

    void hook(fge::CallbackHandler<Types...>& handler, fge::Subscriber* subscriber = nullptr);
 
protected:
    void onDetach(fge::Subscriber* subscriber) override;
 
private:
    struct CalleeData
    {
        inline CalleeData(CalleePtr&& f, fge::Subscriber* subscriber) :
                _f(std::move(f)),
                _subscriber(subscriber)
        {}
 
        CalleePtr _f;
        fge::Subscriber* _subscriber = nullptr;
        bool _markedForDeletion = false;
    };
    using CalleeList = std::vector<CalleeData>;
 
    CalleeList g_callees;
 
    mutable std::recursive_mutex g_mutex;
};

template<class... Types>
class UniqueCallbackHandler : public fge::UniqueSubscription
{
public:
    using CalleePtr = CalleeUniquePtr<void, Types...>;
    using StaticHelpers = CallbackStaticHelpers<void, CalleePtr, Types...>;
 
    UniqueCallbackHandler() = default;
    ~UniqueCallbackHandler() override = default;

    UniqueCallbackHandler([[maybe_unused]] fge::UniqueCallbackHandler<Types...> const& n) :
            fge::UniqueSubscription()
    {}

    UniqueCallbackHandler(fge::CallbackHandler<Types...>&& n) = delete;

    fge::CallbackHandler<Types...>& operator=([[maybe_unused]] fge::CallbackHandler<Types...> const& n)
    {
        return *this;
    };

    fge::CallbackHandler<Types...>& operator=(fge::CallbackHandler<Types...>&& n) = delete;
 
    inline void clear();

    inline fge::CallbackBase<void, Types...>* set(CalleePtr&& callback, fge::Subscriber* subscriber = nullptr);

    inline fge::CallbackFunctor<void, Types...>*
    setFunctor(typename fge::CallbackFunctor<void, Types...>::CallbackFunction func,
               fge::Subscriber* subscriber = nullptr);
    template<typename TLambda>
    inline fge::CallbackLambda<void, Types...>* setLambda(TLambda const& lambda, fge::Subscriber* subscriber = nullptr);
    template<class TObject>
    inline fge::CallbackObjectFunctor<void, TObject, Types...>*
    setObjectFunctor(typename fge::CallbackObjectFunctor<void, TObject, Types...>::CallbackFunctionObject func,
                     TObject* object,
                     Subscriber* subscriber = nullptr);

    void delPtr(void* ptr);
    void delSub(fge::Subscriber* subscriber);
    void del(fge::CallbackBase<Types...>* callback);

    void call(Types... args);
 
protected:
    void onDetach(fge::Subscriber* subscriber) override;
 
private:
    struct CalleeData
    {
        inline CalleeData(CalleePtr&& f, fge::Subscriber* subscriber) :
                _f(std::move(f)),
                _subscriber(subscriber)
        {}
 
        CalleePtr _f;
        fge::Subscriber* _subscriber = nullptr;
    };
 
    CalleeData g_callee{nullptr, nullptr};
 
    mutable std::recursive_mutex g_mutex;
};
 
} // namespace fge
 
#include "FastEngine/C_callback.inl"
 
#endif // _FGE_C_CALLBACKHANDLER_HPP_INCLUDED