/********************************************************************************
 * Copyright (C) 2017-2022 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH  *
 *                                                                              *
 *              This software is distributed under the terms of the             *
 *              GNU Lesser General Public Licence (LGPL) version 3,             *
 *                  copied verbatim in the file "LICENSE"                       *
 ********************************************************************************/

#include <algorithm>
#include <boost/program_options.hpp>
#include <fairlogger/Logger.h>
#include <fairmq/PluginManager.h>
#include <fairmq/plugins/Builtin.h>
#include <fairmq/tools/Strings.h>
#include <iterator>
#include <memory>
#include <sstream>
#include <string>
#include <utility>

using namespace std;
using fair::mq::Plugin;
using fair::mq::tools::ToString;
using fair::mq::tools::ToStrVector;
namespace po = boost::program_options;
namespace dll = boost::dll;
using boost::optional;

const std::string fair::mq::PluginManager::fgkLibPrefix = "fairmq-plugin-";
const std::string fair::mq::PluginManager::fgkLibPrefixAlt = "FairMQPlugin_";

std::vector<boost::dll::shared_library> fair::mq::PluginManager::fgDLLKeepAlive =
    std::vector<boost::dll::shared_library>();

fair::mq::PluginManager::PluginManager()
    : fPluginServices()
{}

fair::mq::PluginManager::PluginManager(const vector<string>& args)
    : fPluginServices()
{
    // Parse command line options
    auto options = ProgramOptions();
    auto vm = po::variables_map{};
    try {
        auto parsed = po::command_line_parser(args).options(options).allow_unregistered().run();
        po::store(parsed, vm);
        po::notify(vm);
    } catch (const po::error& e) {
        throw ProgramOptionsParseError{ToString(
            "Error occured while parsing the 'Plugin Manager' program options: ", e.what())};
    }

    // Process plugin search paths
    auto append = vector<fs::path>{};
    auto prepend = vector<fs::path>{};
    auto searchPaths = vector<fs::path>{};
    if (vm.count("plugin-search-path")) {
        for (const auto& path : vm["plugin-search-path"].as<vector<string>>()) {
            if (path.substr(0, 1) == "<") {
                prepend.emplace_back(path.substr(1));
            } else if (path.substr(0, 1) == ">") {
                append.emplace_back(path.substr(1));
            } else {
                searchPaths.emplace_back(path);
            }
        }
    }

    // Set supplied options
    SetSearchPaths(searchPaths);
    for (const auto& path : prepend) {
        PrependSearchPath(path);
    }
    for (const auto& path : append) {
        AppendSearchPath(path);
    }
    if (vm.count("plugin")) {
        LoadPlugins(vm["plugin"].as<vector<string>>());
    }
}

auto fair::mq::PluginManager::ValidateSearchPath(const fs::path& path) -> void
{
    if (path.empty()) {
        throw BadSearchPath{"Specified path is empty."};
    }
    // we ignore non-existing search paths
    if (fs::exists(path) && !fs::is_directory(path)) {
        throw BadSearchPath{ToString(path, " is not a directory.")};
    }
}

auto fair::mq::PluginManager::SetSearchPaths(const vector<fs::path>& searchPaths) -> void
{
    for_each(begin(searchPaths), end(searchPaths), ValidateSearchPath);
    fSearchPaths = searchPaths;
}

auto fair::mq::PluginManager::AppendSearchPath(const fs::path& path) -> void
{
    ValidateSearchPath(path);
    fSearchPaths.push_back(path);
}

auto fair::mq::PluginManager::PrependSearchPath(const fs::path& path) -> void
{
    ValidateSearchPath(path);
    fSearchPaths.insert(begin(fSearchPaths), path);
}

auto fair::mq::PluginManager::ProgramOptions() -> po::options_description
{
    auto plugin_options = po::options_description{"Plugin Manager"};
    plugin_options.add_options()("plugin-search-path,S",
                                 po::value<vector<string>>()->multitoken(),
                                 "List of plugin search paths.\n\n"
                                 "* Override default search path, e.g.\n"
                                 "  -S /home/user/lib /lib\n"
                                 "* Append(>) or prepend(<) to default search path, e.g.\n"
                                 "  -S >/lib </home/user/lib\n"
                                 "* If you mix the overriding and appending/prepending syntaxes, "
                                 "the overriding paths act as default search path, e.g.\n"
                                 "  -S /usr/lib >/lib </home/user/lib /usr/local/lib results in "
                                 "/home/user/lib,/usr/local/lib,/usr/lib/,/lib\n"
                                 "If nothing is found, the default dynamic library lookup is "
                                 "performed, see man ld.so(8) for details.")(
        "plugin,P",
        po::value<vector<string>>(),
        "List of plugin names to load in order,"
        "e.g. if the file is called 'libfairmq-plugin-example.so', just list 'example' or "
        "'d:example' here."
        "To load a prelinked plugin, list 'p:example' here.");

    return plugin_options;
}

auto fair::mq::PluginManager::LoadPlugin(const string& pluginName) -> void
{
    if (pluginName.substr(0, 2) == "p:") {
        // Mechanism A: prelinked dynamic
        LoadPluginPrelinkedDynamic(pluginName.substr(2));
    } else if (pluginName.substr(0, 2) == "d:") {
        // Mechanism B: dynamic
        LoadPluginDynamic(pluginName.substr(2));
    } else if (pluginName.substr(0, 2) == "s:") {
        // Mechanism C: static (builtin)
        LoadPluginStatic(pluginName.substr(2));
    } else {
        // Mechanism B: dynamic (default)
        LoadPluginDynamic(pluginName);
    }
}

auto fair::mq::PluginManager::LoadPluginPrelinkedDynamic(const string& pluginName) -> void
{
    // Load symbol
    if (fPluginFactories.find(pluginName) == fPluginFactories.end()) {
        try {
            LoadSymbols(pluginName, dll::program_location());
            fPluginOrder.push_back(pluginName);
        } catch (boost::system::system_error& e) {
            throw PluginLoadError(
                ToString("An error occurred while loading prelinked dynamic plugin ",
                         pluginName,
                         ": ",
                         e.what()));
        }
    }
}

auto fair::mq::PluginManager::SearchPluginFile(const string& pluginName) const
    -> fs::path
{
    for (const auto& searchPath : SearchPaths()) {
        for (const auto& libPrefix : {fgkLibPrefix, fgkLibPrefixAlt}) {
            auto const file =
                searchPath
                / ToString("lib",
                           libPrefix,
                           pluginName,
                           boost::dll::detail::shared_library_impl::suffix().native());
            auto const found = fs::exists(file);
            if (found) {
                return file;
            }
        }
    }
    throw PluginNotFound(ToString("Could not find plugin file for plugin ", pluginName));
}

auto fair::mq::PluginManager::LoadPluginDynamic(const string& pluginName) -> void
{
    if (fPluginFactories.find(pluginName) != fPluginFactories.end()) {
        return;   // already loaded, nothing to do
    }

    // Search in configured search path
    try {
        LoadSymbols(pluginName, SearchPluginFile(pluginName), dll::load_mode::rtld_global);
        fPluginOrder.push_back(pluginName);
        return;
    } catch (PluginNotFound& e) {
        // ignore
    } catch (boost::system::system_error& e) {
        // ignore
    }

    // Search with system logic (including RPATH, LD_LIBRARY_PATH)
    for (const auto& libPrefix : {fgkLibPrefix, fgkLibPrefixAlt}) {
        try {
            // LoadSymbols(pluginName,
            // ToString(LibPrefix(), pluginName),
            // dll::load_mode::search_system_folders | dll::load_mode::append_decorations);
            // Not sure, why the above does not work. Workaround for now:
            LoadSymbols(pluginName,
                        ToString("lib",
                                 libPrefix,
                                 pluginName,
                                 boost::dll::detail::shared_library_impl::suffix().native()),
                        dll::load_mode::search_system_folders | dll::load_mode::rtld_global);
            fPluginOrder.push_back(pluginName);
            return;
        } catch (boost::system::system_error& e) {
            // ignore
        }
    }

    throw PluginLoadError(ToString("Could not load dynamic plugin ",
                                   pluginName,
                                   " from configured search paths (-S) nor with ",
                                   "system lookup (system libdirs, RUNPATH, $LD_LIBRARY_PATH)."));
}

auto fair::mq::PluginManager::LoadPluginStatic(const string& pluginName) -> void
{
    // Load symbol
    if (fPluginFactories.find(pluginName) == fPluginFactories.end()) {
        try {
            if ("control" == pluginName) {
                try {
                    fPluginProgOptions.insert(
                        {pluginName, plugins::ControlPluginProgramOptions().value()});
                } catch (const boost::bad_optional_access&) {
                    /* just ignore, if no prog options are declared */
                }
            } else if ("config" == pluginName) {
                try {
                    fPluginProgOptions.insert(
                        {pluginName, plugins::ConfigPluginProgramOptions().value()});
                } catch (const boost::bad_optional_access&) {
                    /* just ignore, if no prog options are declared */
                }
            } else {
                LoadSymbols(pluginName, dll::program_location());
            }
            fPluginOrder.push_back(pluginName);
        } catch (boost::system::system_error& e) {
            throw PluginLoadError(ToString(
                "An error occurred while loading static plugin ", pluginName, ": ", e.what()));
        }
    }
}

auto fair::mq::PluginManager::InstantiatePlugin(const string& pluginName) -> void
{
    if (fPlugins.find(pluginName) == fPlugins.end()) {
        if ("control" == pluginName) {
            fPlugins[pluginName] = plugins::Make_control_Plugin(fPluginServices.get());
        } else if ("config" == pluginName) {
            fPlugins[pluginName] = plugins::Make_config_Plugin(fPluginServices.get());
        } else {
            fPlugins[pluginName] = fPluginFactories[pluginName](*fPluginServices);
        }
    }
}

auto fair::mq::PluginManager::InstantiatePlugins() -> void
{
    for (const auto& pluginName : fPluginOrder) {
        try {
            InstantiatePlugin(pluginName);
        } catch (std::exception& e) {
            throw PluginInstantiationError(ToString(
                "An error occurred while instantiating plugin ", pluginName, ": ", e.what()));
        }
    }
}