arg_parser.cpp

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// SPDX-License-Identifier: GPL-2.0-only
//
// Copyright (c) 2024-present FERS Contributors (see AUTHORS.md).
//
// See the GNU GPLv2 LICENSE file in the FERS project root for more information.
 
/**
 * @file arg_parser.cpp
 * @brief Implementation of the command-line argument parser for the application.
 */
 
#include "arg_parser.h"
 
#include <algorithm>
#include <exception>
#include <filesystem>
#include <iostream>
#include <unordered_map>
#include <utility>
#include <vector>
 
namespace
{
    /**
     * @brief Checks if the given file has a valid log file extension.
     *
     * @param filePath The path of the log file.
     * @return true if the file has a valid extension, false otherwise.
     */
    bool isValidLogFileExtension(const std::string& filePath) noexcept
    {
        static const std::vector<std::string> VALID_EXTENSIONS = {".log", ".txt"};
        std::string extension = std::filesystem::path(filePath).extension().string();
        std::ranges::transform(extension, extension.begin(), tolower);
        return std::ranges::find(VALID_EXTENSIONS, extension) != VALID_EXTENSIONS.end();
    }
 
    /**
     * @brief Parses the logging level from a string representation.
     *
     * @param level The string representation of the logging level.
     * @return std::optional<Level> The corresponding logging level, or `std::nullopt` if invalid.
     */
    std::optional<fers_log_level_t> parseLogLevel(const std::string& level) noexcept
    {
        static const std::unordered_map<std::string, fers_log_level_t> LEVEL_MAP = {
            {"TRACE", FERS_LOG_TRACE},     {"DEBUG", FERS_LOG_DEBUG}, {"INFO", FERS_LOG_INFO},
            {"WARNING", FERS_LOG_WARNING}, {"ERROR", FERS_LOG_ERROR}, {"FATAL", FERS_LOG_FATAL}};
 
        if (const auto it = LEVEL_MAP.find(level); it != LEVEL_MAP.end())
        {
            return it->second;
        }
        return std::nullopt;
    }
 
    /**
     * @brief Handles the log-level argument and sets the logging level.
     *
     * @param arg The log-level argument string.
     * @param config The configuration object to update.
     * @return std::expected<void, std::string> An expected object with an error message if the log level is invalid.
     */
    std::expected<void, std::string> handleLogLevel(const std::string& arg, core::Config& config) noexcept
    {
        const std::string level_str = arg.substr(12);
        if (const auto level = parseLogLevel(level_str))
        {
            config.log_level = *level;
            return {};
        }
 
        std::cerr << "[ERROR] Invalid log level '" << level_str << "'\n";
        return std::unexpected("Invalid log level: " + level_str);
    }
 
    /**
     * @brief Handles the log-file argument and sets the log file path.
     *
     * @param arg The log-file argument string.
     * @param config The configuration object to update.
     * @return std::expected<void, std::string> An expected object with an error message if the log file path is
     * invalid.
     */
    std::expected<void, std::string> handleLogFile(const std::string& arg, core::Config& config) noexcept
    {
        if (std::string log_file_path = arg.substr(11); isValidLogFileExtension(log_file_path))
        {
            config.log_file = log_file_path;
            return {};
        }
        else
        {
            std::cerr << "[ERROR] Invalid log file extension. Must be .log or .txt\n";
            return std::unexpected("Invalid log file extension: " + log_file_path);
        }
    }
 
    /**
     * @brief Handles the number of threads argument and sets the number of threads.
     *
     * @param arg The number of threads argument string.
     * @param config The configuration object to update.
     * @return std::expected<void, std::string> An expected object with an error message if the number of threads is
     * invalid.
     */
    std::expected<void, std::string> handleNumThreads(const std::string& arg, core::Config& config) noexcept
    {
        try
        {
            config.num_threads = std::stoi(arg.substr(3));
            if (config.num_threads == 0)
            {
                return std::unexpected("Number of threads must be greater than 0");
            }
 
            if (const unsigned max_threads = std::thread::hardware_concurrency();
                max_threads > 0 && config.num_threads > max_threads)
            {
                std::cerr << "[WARNING] Thread count exceeds available processors. Clamping.\n";
                config.num_threads = max_threads;
            }
            return {};
        }
        catch (const std::exception&)
        {
            return std::unexpected("Invalid number of threads specified.");
        }
    }
 
    /**
     * @brief Handles the command-line argument and updates the configuration.
     *
     * @param arg The command-line argument string.
     * @param config The configuration object to update.
     * @param scriptFileSet A flag indicating if the script file has been set.
     * @param programName The name of the program executable.
     * @return std::expected<void, std::string> An expected object with an error message if the argument is invalid.
     */
    std::expected<void, std::string> handleArgument(const std::string& arg, core::Config& config, bool& scriptFileSet,
                                                    const char* programName) noexcept
    {
        if (arg == "--help" || arg == "-h")
        {
            core::showHelp(programName);
            return std::unexpected("Help requested.");
        }
        if (arg == "--version" || arg == "-v")
        {
            core::showVersion();
            return std::unexpected("Version requested.");
        }
        if (arg.rfind("--log-level=", 0) == 0)
        {
            return handleLogLevel(arg, config);
        }
        if (arg.rfind("--log-file=", 0) == 0)
        {
            return handleLogFile(arg, config);
        }
        if (arg.rfind("-n=", 0) == 0)
        {
            return handleNumThreads(arg, config);
        }
        if (arg == "--no-validate")
        {
            config.validate = false;
            return {};
        }
        if (arg == "--kml")
        {
            config.generate_kml = true;
            return {};
        }
        if (arg[0] != '-' && !scriptFileSet)
        {
            config.script_file = arg;
            scriptFileSet = true;
            return {};
        }
 
        std::cerr << "[ERROR] Unrecognized option: '" << arg << "'\n";
        return std::unexpected("Unrecognized argument: " + arg);
    }
}
 
namespace core
{
    void showHelp(const char* programName) noexcept
    {
        std::cout << R"(/------------------------------------------------\
| FERS - The Flexible Extensible Radar Simulator |
| Version 1.0.0                                  |
\------------------------------------------------/
Usage: )" << programName
                  << R"( <scriptfile> [options]
 
Options:
  --help, -h              Show this help message and exit
  --version, -v           Show version information and exit
  --no-validate           Disable XML schema validation before running.
  --kml                   Generate a KML visualization of the scenario and exit. The output file
                          will have the same name as the input file with a .kml extension.
  --log-level=<level>     Set the logging level (TRACE, DEBUG, INFO, WARNING, ERROR, FATAL)
  --log-file=<file>       Log output to the specified .log or .txt file as well as the console.
  -n=<threads>            Number of threads to use
 
Arguments:
  <scriptfile>            Path to the simulation script file (XML)
 
Example:
  )" << programName
                  << R"( simulation.fersxml --log-level=DEBUG --log-file=output.log -n=4
 
This program runs radar simulations based on an XML script file.
Make sure the script file follows the correct format to avoid errors.
)";
    }
 
    void showVersion() noexcept
    {
        std::cout << R"(
/------------------------------------------------\
| FERS - The Flexible Extensible Radar Simulator |
| Version 1.0.0                                  |
| Author: Marc Brooker                           |
\------------------------------------------------/
)" << std::endl;
    }
 
    std::expected<Config, std::string> parseArguments(const int argc, char* argv[]) noexcept
    {
        Config config;
        bool script_file_set = false;
 
        if (argc < 2)
        {
            showHelp(argv[0]);
            return std::unexpected("No arguments provided.");
        }
 
        for (int i = 1; i < argc; ++i)
        {
            if (const auto result = handleArgument(argv[i], config, script_file_set, argv[0]); !result)
            {
                return std::unexpected(result.error());
            }
        }
 
        if (!script_file_set)
        {
            return std::unexpected("No script file provided.");
        }
        return config;
    }
}