#pragma once
#ifndef META_RUNTIME_META_REGISTRY_H
#define META_RUNTIME_META_REGISTRY_H

#include "meta_object.h"
#include <functional>
#include <unordered_map>

namespace meta {

/**
 * Registry
 **/

template<typename... Args>
class MetaRegistry {
public:
    static MetaRegistry *Instance();
    static bool Register(const std::string &obj_name,
                         std::function<MetaObject *(Args &&...)> creator);
    static bool Unregister(const std::string &obj_name);

private:
    bool RegisterImpl(const std::string &obj_name, std::function<MetaObject *(Args &&...)> creator);
    bool UnregisterImpl(const std::string &obj_name);

    std::unordered_map<std::string, std::function<MetaObject *(Args &&...)>> creators_;
};

template<typename... Args>
MetaRegistry<Args...> *
MetaRegistry<Args...>::Instance()
{
    static MetaRegistry<Args...> instance;
    return &instance;
}

template<typename... Args>
bool
MetaRegistry<Args...>::Register(const std::string &obj_name,
                                std::function<MetaObject *(Args &&...)> creator)
{
    return Instance()->RegisterImpl(obj_name, creator);
}

template<typename... Args>
bool
MetaRegistry<Args...>::Unregister(const std::string &obj_name)
{
    return Instance()->UnregisterImpl(obj_name);
}

template<typename... Args>
bool
MetaRegistry<Args...>::RegisterImpl(const std::string &obj_name,
                                    std::function<MetaObject *(Args &&...)> creator)
{
    return creators_.insert({obj_name, creator}).second;
}

template<typename... Args>
bool
MetaRegistry<Args...>::UnregisterImpl(const std::string &obj_name)
{
    return creators_.erase(obj_name) > 0;
}

}// namespace meta

#endif// META_RUNTIME_META_REGISTRY_H