// This file Copyright © 2012-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.

#include <array>
#include <cstdlib> // for strtoul()
#include <chrono>
#include <cstdint> // for uint32_t
#include <future>
#include <string>
#include <string_view>

#include <fmt/format.h>

#include <libtransmission/transmission.h>

#include <libtransmission/error.h>
#include <libtransmission/file.h>
#include <libtransmission/log.h>
#include <libtransmission/makemeta.h>
#include <libtransmission/tr-getopt.h>
#include <libtransmission/utils.h>
#include <libtransmission/version.h>

#include "units.h"

using namespace std::literals;

namespace
{

char constexpr MyName[] = "transmission-create";
char constexpr Usage[] = "Usage: transmission-create [options] <file|directory>";

uint32_t constexpr KiB = 1024;

auto constexpr Options = std::array<tr_option, 10>{
    { { 'p', "private", "Allow this torrent to only be used with the specified tracker(s)", "p", false, nullptr },
      { 'r', "source", "Set the source for private trackers", "r", true, "<source>" },
      { 'o', "outfile", "Save the generated .torrent to this filename", "o", true, "<file>" },
      { 's', "piecesize", "Set the piece size in KiB, overriding the preferred default", "s", true, "<KiB>" },
      { 'c', "comment", "Add a comment", "c", true, "<comment>" },
      { 't', "tracker", "Add a tracker's announce URL", "t", true, "<url>" },
      { 'w', "webseed", "Add a webseed URL", "w", true, "<url>" },
      { 'x', "anonymize", "Omit \"Creation date\" and \"Created by\" info", nullptr, false, nullptr },
      { 'V', "version", "Show version number and exit", "V", false, nullptr },
      { 0, nullptr, nullptr, nullptr, false, nullptr } }
};

struct app_options
{
    tr_announce_list trackers;
    std::vector<std::string> webseeds;
    std::string outfile;
    std::string_view comment;
    std::string_view infile;
    std::string_view source;
    uint32_t piece_size = 0;
    bool anonymize = false;
    bool is_private = false;
    bool show_version = false;
};

int parseCommandLine(app_options& options, int argc, char const* const* argv)
{
    int c;
    char const* optarg;

    while ((c = tr_getopt(Usage, argc, argv, std::data(Options), &optarg)) != TR_OPT_DONE)
    {
        switch (c)
        {
        case 'V':
            options.show_version = true;
            break;

        case 'p':
            options.is_private = true;
            break;

        case 'o':
            options.outfile = optarg;
            break;

        case 'c':
            options.comment = optarg;
            break;

        case 't':
            options.trackers.add(optarg, options.trackers.nextTier());
            break;

        case 'w':
            options.webseeds.emplace_back(optarg);
            break;

        case 's':
            if (optarg != nullptr)
            {
                char* endptr = nullptr;
                options.piece_size = strtoul(optarg, &endptr, 10) * KiB;
                if (endptr != nullptr && *endptr == 'M')
                {
                    options.piece_size *= KiB;
                }
            }
            break;

        case 'r':
            options.source = optarg;
            break;

        case 'x':
            options.anonymize = true;
            break;

        case TR_OPT_UNK:
            options.infile = optarg;
            break;

        default:
            return 1;
        }
    }

    return 0;
}

std::string tr_getcwd()
{
    tr_error* error = nullptr;
    auto cur = tr_sys_dir_get_current(&error);
    {
        fprintf(stderr, "getcwd error: \"%s\"", error->message);
        tr_error_free(error);
    }
    return cur;
}

} // namespace

int tr_main(int argc, char* argv[])
{
    tr_logSetLevel(TR_LOG_ERROR);
    tr_formatter_mem_init(MemK, MemKStr, MemMStr, MemGStr, MemTStr);
    tr_formatter_size_init(DiskK, DiskKStr, DiskMStr, DiskGStr, DiskTStr);
    tr_formatter_speed_init(SpeedK, SpeedKStr, SpeedMStr, SpeedGStr, SpeedTStr);

    auto options = app_options{};
    if (parseCommandLine(options, argc, (char const* const*)argv) != 0)
    {
        return EXIT_FAILURE;
    }

    if (options.show_version)
    {
        fprintf(stderr, "%s %s\n", MyName, LONG_VERSION_STRING);
        return EXIT_SUCCESS;
    }

    if (std::empty(options.infile))
    {
        fprintf(stderr, "ERROR: No input file or directory specified.\n");
        tr_getopt_usage(MyName, Usage, std::data(Options));
        fprintf(stderr, "\n");
        return EXIT_FAILURE;
    }

    if (std::empty(options.outfile))
    {
        tr_error* error = nullptr;
        auto const base = tr_sys_path_basename(options.infile, &error);

        if (std::empty(base))
        {
            fprintf(stderr, "ERROR: Cannot deduce output path from input path: %s\n", error->message);
            return EXIT_FAILURE;
        }

        options.outfile = fmt::format("{:s}/{:s}.torrent"sv, tr_getcwd(), base);
    }

    if (std::empty(options.trackers))
    {
        if (options.is_private)
        {
            fprintf(stderr, "ERROR: no trackers specified for a private torrent\n");
            return EXIT_FAILURE;
        }
        else
        {
            printf("WARNING: no trackers specified\n");
        }
    }

    fmt::print("Creating torrent \"{:s}\"\n", options.outfile);

    auto builder = tr_metainfo_builder(options.infile);
    auto const n_files = builder.fileCount();
    if (n_files == 0U)
    {
        fprintf(stderr, "ERROR: Cannot find specified input file or directory.\n");
        return EXIT_FAILURE;
    }

    for (tr_file_index_t i = 0; i < n_files; ++i)
    {
        auto const& path = builder.path(i);
        if (!tr_torrent_files::isSubpathPortable(path))
        {
            fmt::print(stderr, "WARNING\n");
            fmt::print(stderr, "filename \"{:s}\" may not be portable on all systems.\n", path);
            fmt::print(stderr, "consider \"{:s}\" instead.\n", tr_torrent_files::makeSubpathPortable(path));
        }
    }

    if (options.piece_size != 0 && !builder.setPieceSize(options.piece_size))
    {
        fmt::print(stderr, "ERROR: piece size must be at least 16 KiB and must be a power of two.\n");
        return EXIT_FAILURE;
    }

    fmt::print(
        ngettext("{:d} files, {:s}\n", "{:d} file, {:s}\n", builder.fileCount()),
        builder.fileCount(),
        tr_formatter_size_B(builder.totalSize()));

    fmt::print(
        ngettext("{:d} pieces, {:s} each\n", "{:d} piece, {:s}\n", builder.pieceCount()),
        builder.pieceCount(),
        tr_formatter_size_B(builder.pieceSize()));

    if (!std::empty(options.comment))
    {
        builder.setComment(options.comment);
    }

    if (!std::empty(options.source))
    {
        builder.setSource(options.source);
    }

    builder.setPrivate(options.is_private);
    builder.setAnonymize(options.anonymize);
    builder.setWebseeds(std::move(options.webseeds));
    builder.setAnnounceList(std::move(options.trackers));

    auto future = builder.makeChecksums();
    auto last = std::optional<tr_piece_index_t>{};
    while (future.wait_for(std::chrono::milliseconds(500)) != std::future_status::ready)
    {
        auto const [current, total] = builder.checksumStatus();

        if (!last || current != *last)
        {
            fmt::print("\rPiece {:d}/{:d} ...", current, total);
            fflush(stdout);
            last = current;
        }
    }

    fmt::print(" ");

    if (tr_error* error = future.get(); error != nullptr)
    {
        fmt::print("ERROR: {:s} {:d}\n", error->message, error->code);
        tr_error_free(error);
        return EXIT_FAILURE;
    }

    if (tr_error* error = nullptr; !builder.save(options.outfile, &error))
    {
        fmt::print("ERROR: could not save \"{:s}\": {:s} {:d}\n", options.outfile, error->message, error->code);
        tr_error_free(error);
        return EXIT_FAILURE;
    }

    fmt::print("done!\n");
    return EXIT_SUCCESS;
}