#ifndef SOPHIAR2_TINY_SIGNAL_HPP
#define SOPHIAR2_TINY_SIGNAL_HPP

#include <boost/intrusive/list.hpp>

#include <type_traits>

namespace sophiar {

    template<typename... Args>
    class signal_muxer;

    template<typename... Args>
    class tiny_signal {
    public:

        using muxer_type = signal_muxer<Args...>;

        using hook_type = boost::intrusive::list_base_hook<
                boost::intrusive::link_mode<
                        boost::intrusive::auto_unlink>>;

        // 其他对象不得持有 listener
        // 所有调用应该以引用进行
        struct listener_type : public hook_type {

            virtual ~listener_type() = default;

            virtual void on_signal_received(Args... args) = 0;
        };

        using list_type = boost::intrusive::list<
                listener_type, boost::intrusive::constant_time_size<false>>;

        void add_listener(listener_type &node) {
            if (node.is_linked()) {
                node.unlink();
            }
            node_list.push_back(node);
        }

        void emit_signal(Args... args) {
            for (auto &node: node_list) {
                node.on_signal_received(args...);
            }
        }

    private:
        list_type node_list;

    };

}

#endif //SOPHIAR2_TINY_SIGNAL_HPP