RetainTree.h

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/*
 * SNode.C - a slim toolkit for network communication
 * Copyright (C) Volker Christian <me@vchrist.at>
 *               2020, 2021, 2022, 2023, 2024, 2025
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef IOT_MQTT_SERVER_BROKER_TOPICTREE_H
#define IOT_MQTT_SERVER_BROKER_TOPICTREE_H
 
#include "iot/mqtt/server/broker/Message.h"
 
namespace iot::mqtt::server::broker {
    class Broker;
} // namespace iot::mqtt::server::broker
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include <cstdint>
#include <map>
#include <nlohmann/json_fwd.hpp>
#include <string>
 
#endif // DOXYGEN_SHOULD_SKIP_THIS
 
namespace iot::mqtt::server::broker {
 
    class RetainTree {
    public:
        explicit RetainTree(iot::mqtt::server::broker::Broker* broker);
 
        void retain(Message&& message);
        void appear(const std::string& clientId, const std::string& topic, uint8_t qoS);
 
        nlohmann::json toJson() const;
        void fromJson(const nlohmann::json& json);
 
        void clear();
 
    private:
        class TopicLevel {
        public:
            explicit TopicLevel(iot::mqtt::server::broker::Broker* broker);
 
            void retain(const Message& message, std::string topic);
            bool release(std::string topic);
 
            void appear(const std::string& clientId, std::string topic, uint8_t qoS);
 
            TopicLevel& fromJson(const nlohmann::json& json);
            nlohmann::json toJson() const;
 
            void clear();
 
        private:
            void appear(const std::string& clientId, uint8_t clientQoS);
 
            Message message;
 
            std::map<std::string, TopicLevel> subTopicLevels;
 
            iot::mqtt::server::broker::Broker* broker = nullptr;
        };
 
        TopicLevel head;
    };
 
} // namespace iot::mqtt::server::broker
 
#endif // APPS_MQTT_SERVER_TOPICTREE_H