/*  This file is part of epubgrep.
 *  Copyright © 2021 tastytea <tastytea@tastytea.de>
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, version 3.
 *
 *  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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "files.hpp"
#include "fs-compat.hpp"
#include "options.hpp"
#include "output.hpp"
#include "search.hpp"
#include "zip.hpp"

#include <boost/locale/generator.hpp>
#include <boost/locale/message.hpp>
#include <fmt/format.h>
#include <fmt/ostream.h> // For compatibility with fmt 4.

#include <clocale>
#include <cmath>
#include <cstdint>
#include <cstdlib>
#include <exception>
#include <fstream>
#include <future>
#include <iostream>
#include <locale>
#include <mutex>
#include <string>
#include <string_view>
#include <system_error>
#include <thread>
#include <vector>

int main(int argc, char *argv[])
{
    using namespace epubgrep;

    using boost::locale::translate;
    using fmt::format;
    using std::cerr;
    using std::cout;
    using std::string;
    using std::vector;

    // locale_generator("").name.c_str() returns "*" instead of "". That's why
    // the global C locale isn't changed. So we have to set it additionally.
    std::setlocale(LC_ALL, "");
    boost::locale::generator locale_generator;
    locale_generator.add_messages_path("translations");
    locale_generator.add_messages_path("/usr/share/locale");
    locale_generator.add_messages_domain("epubgrep");
    std::locale::global(locale_generator(""));
    cout.imbue(std::locale());
    cerr.imbue(std::locale());

    options::options opts;
    try
    {
        opts = options::parse_options(argc, argv);
    }
    catch (std::exception &e)
    { // Exceptions we can't recover from or ones we don't know.
        cerr << translate("ERROR: ") << e.what();
        cerr << translate(" (while parsing options)") << '\n';
        return EXIT_FAILURE;
    }

    if (opts.help || opts.version)
    {
        return EXIT_SUCCESS;
    }

    int return_code{EXIT_SUCCESS};

    vector<fs::path> input_files;
    if (opts.input_file.empty())
    {
        cout << "NO INPUT FILE\n";
        // TODO: Read data from stdin.
        return EXIT_FAILURE;
    }
    for (const auto &filepath : opts.input_file)
    {
        if (!opts.recursive && !opts.dereference_recursive)
        {

            input_files.emplace_back(filepath);
        }
        else
        {
            try
            {
                auto files_in_dir{
                    files::list_recursive(filepath,
                                          opts.dereference_recursive)};
                input_files.insert(input_files.end(), files_in_dir.begin(),
                                   files_in_dir.end());
            }
            catch (const fs::filesystem_error &e)
            {
                if (e.code().value() == 20)
                { // Is not a directory.
                    input_files.emplace_back(filepath);
                    continue;
                }

                cerr << translate("ERROR: ")
                     << format(translate("Could not open {0:s}: {1:s}").str(),
                               e.path1(), e.what())
                     << '\n';
                return_code = EXIT_FAILURE;
            }
        }
    }

    search::settings search_settings;
    search_settings.regex = opts.regex;
    search_settings.grep_like = opts.grep;
    search_settings.ignore_case = opts.ignore_case;
    search_settings.raw = opts.raw;
    search_settings.context = opts.context;

    vector<vector<search::match>> matches_all;
    std::mutex mutex_matches_all;
    vector<std::future<int>> futurepool;

    auto search_file{
        [&opts, &matches_all, &mutex_matches_all,
         &search_settings](const fs::path &filepath)
        {
            for (const auto &regex : opts.regexp)
            {
                try
                {
                    auto matches{
                        search::search(filepath, regex, search_settings)};
                    std::lock_guard<std::mutex> guard(mutex_matches_all);
                    matches_all.emplace_back(matches);
                }
                catch (const zip::exception &e)
                {
                    if (opts.ignore_archive_errors && e.code == 1)
                    { // File is probably not an EPUB.
                        return EXIT_SUCCESS;
                    }

                    cerr << translate("ERROR: ") << e.what() << '\n';
                    return EXIT_FAILURE;
                }
                catch (const std::ifstream::failure &e)
                {
                    cerr << translate("ERROR: ");
                    if (e.code() == std::errc::permission_denied)
                    {
                        cerr << translate("Permission denied.");
                    }
                    else
                    { // std::ifstream seems to always return a generic error?
                        cerr << translate("Probably permission denied.") << " ("
                             << e.what() << ')';
                    }

                    cerr << format(translate(" (while opening {0:s})").str(),
                                   filepath)
                         << '\n';
                }
            }

            return EXIT_SUCCESS;
        }};

    auto futures_cleanup{
        [&futurepool, &return_code](const bool wait = false)
        {
            using namespace std::chrono_literals;

            for (auto it{futurepool.begin()}; it != futurepool.end();)
            {
                if (!wait && it->wait_for(100ms) != std::future_status::ready)
                {
                    ++it;
                    continue;
                }

                if (int ret{}; (ret = it->get()) != EXIT_SUCCESS)
                {
                    return_code = ret;
                }
                futurepool.erase(it);
            }

            return EXIT_SUCCESS;
        }};

    const auto max_threads{
        []
        {
            auto n{static_cast<double>(std::thread::hardware_concurrency())};
            return static_cast<std::uint32_t>(std::ceil(n / 2 + n / 4));
        }()};

    for (const auto &filepath : input_files)
    {
        while (futurepool.size() >= max_threads)
        {
            futures_cleanup();
        }
        futurepool.emplace_back(
            std::async(std::launch::async, search_file, filepath));

        if (!matches_all.empty())
        {
            output::print_matches(matches_all[0], opts,
                                  input_files.size() == 1);
            std::lock_guard<std::mutex> guard(mutex_matches_all);
            matches_all.erase(matches_all.begin());
        }
    }
    futures_cleanup(true);

    for (const auto &matches : matches_all)
    {
        output::print_matches(matches, opts, input_files.size() == 1);
    }

    return return_code;
}