nats_client.hpp

/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * Copyright (C) 2026 Marco Craveiro <marco.craveiro@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify it under
 * the terms of the GNU 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */
#ifndef ORES_NATS_SERVICE_NATS_CLIENT_HPP
#define ORES_NATS_SERVICE_NATS_CLIENT_HPP
 
#include <chrono>
#include <functional>
#include <memory>
#include <optional>
#include <span>
#include <string>
#include <string_view>
#include "ores.logging/make_logger.hpp"
#include "ores.nats/config/nats_options.hpp"
#include "ores.nats/domain/headers.hpp"
#include "ores.nats/domain/message.hpp"
#include "ores.nats/service/session_expired_error.hpp"
 
namespace ores::nats::service { class client; }
 
namespace ores::nats::service {
 
class nats_client {
private:
    inline static std::string_view logger_name = "ores.nats.service.nats_client";
 
    [[nodiscard]] static auto& lg() {
        using namespace ores::logging;
        static auto instance = make_logger(logger_name);
        return instance;
    }
 
public:
    struct login_info {
        std::string jwt;
        std::string username;
        std::string tenant_id;
        std::string tenant_name;
    };
 
    using token_provider = std::function<std::string(bool force)>;
 
    // -- Interactive path --
 
    nats_client() = default;
 
    void connect(config::nats_options opts);
 
    void disconnect();
 
    [[nodiscard]] bool is_connected() const noexcept;
 
    void set_auth(login_info info);
 
    void clear_auth();
 
    [[nodiscard]] const login_info& auth() const;
 
    // -- Service path --
 
    nats_client(client& nats, token_provider provider);
 
    // -- Common --
 
    [[nodiscard]] bool is_logged_in() const noexcept;
 
    [[nodiscard]] message request(std::string_view subject,
        std::string_view json_body);
 
    [[nodiscard]] message authenticated_request(std::string_view subject,
        std::string_view json_body,
        std::chrono::milliseconds timeout = std::chrono::seconds(30));
 
    [[nodiscard]] message authenticated_request(std::string_view subject,
        std::span<const std::byte> body,
        std::chrono::milliseconds timeout = std::chrono::seconds(10));
 
    [[nodiscard]] nats_client with_delegation(std::string token) const;
 
    [[nodiscard]] nats_client with_correlation_id(std::string cid) const;
 
    [[nodiscard]] std::shared_ptr<client> get_client() const;
 
private:
    [[nodiscard]] client& active_client() const;
 
    [[nodiscard]] message do_authenticated_request(std::string_view subject,
        std::span<const std::byte> body, std::chrono::milliseconds timeout);
 
    // Interactive path state
    std::shared_ptr<client> owned_client_;
    std::optional<login_info> auth_;
 
    // Service path state
    client* external_client_ = nullptr;
    token_provider token_provider_;
 
    // Optional delegation token forwarded as X-Delegated-Authorization.
    std::string delegation_token_;
 
    // Optional correlation ID forwarded as Nats-Correlation-Id.
    std::string correlation_id_;
};
 
[[nodiscard]] std::string extract_bearer(const ores::nats::message& msg);
 
} // namespace ores::nats::service
 
#endif