session_file.hpp

/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * Copyright (C) 2025 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_COMMS_RECORDING_SESSION_FILE_HPP
#define ORES_COMMS_RECORDING_SESSION_FILE_HPP
 
#include <array>
#include <chrono>
#include <cstdint>
#include <expected>
#include <string>
#include <boost/uuid/uuid.hpp>
#include "ores.comms/messaging/message_types.hpp"
 
namespace ores::comms::recording {
 
constexpr std::array<std::uint8_t, 8> SESSION_FILE_MAGIC = {
    0x4F, 0x52, 0x45, 0x53, 0x2D, 0x52, 0x45, 0x43
};
 
constexpr std::uint16_t SESSION_FILE_VERSION = 1;
 
enum class frame_direction : std::uint8_t {
    sent = 0x00,     
    received = 0x01  
};
 
struct session_file_header final {
    std::array<std::uint8_t, 8> magic;
    std::uint16_t version;
    std::uint16_t reserved1;
    std::uint16_t protocol_version_major;
    std::uint16_t protocol_version_minor;
    boost::uuids::uuid session_id;
    std::int64_t start_timestamp_us;
    std::uint16_t server_address_length;
    messaging::compression_type compression;
    std::array<std::uint8_t, 21> reserved2;
 
    static constexpr size_t size = 64;
};
 
static_assert(sizeof(session_file_header) == session_file_header::size,
    "session_file_header must be exactly 64 bytes");
 
struct frame_record_header final {
    std::int64_t timestamp_offset_us;
    std::uint32_t frame_size;
    frame_direction direction;
    std::array<std::uint8_t, 3> reserved;
 
    static constexpr size_t size = 16;
};
 
static_assert(sizeof(frame_record_header) == frame_record_header::size,
    "frame_record_header must be exactly 16 bytes");
 
enum class session_file_error {
    none = 0,
    file_open_failed,
    file_write_failed,
    file_read_failed,
    invalid_magic,
    unsupported_version,
    corrupt_file,
    end_of_file,     
    unexpected_eof   
};
 
std::string generate_session_filename(
    const boost::uuids::uuid& session_id,
    std::chrono::system_clock::time_point start_time);
 
}
 
#endif