// This file Copyright © 2008-2022 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 <cerrno>
#include <cstdio> /* printf */
#include <cstdlib> /* atoi */
#include <iostream>
#include <memory>
#include <string>
#include <string_view>

#ifdef HAVE_SYSLOG
#include <syslog.h>
#endif

#ifdef _WIN32
#include <process.h> /* getpid */
#else
#include <unistd.h> /* getpid */
#endif

#include <event2/event.h>

#include <fmt/core.h>

#include <libtransmission/transmission.h>

#include <libtransmission/error.h>
#include <libtransmission/file.h>
#include <libtransmission/log.h>
#include <libtransmission/timer-ev.h>
#include <libtransmission/tr-getopt.h>
#include <libtransmission/tr-macros.h>
#include <libtransmission/tr-strbuf.h>
#include <libtransmission/utils.h>
#include <libtransmission/variant.h>
#include <libtransmission/version.h>
#include <libtransmission/watchdir.h>

#include "daemon.h"

#ifdef USE_SYSTEMD

#include <systemd/sd-daemon.h>

#else

static void sd_notify(int /*status*/, char const* /*str*/)
{
    // no-op
}

static void sd_notifyf(int /*status*/, char const* /*fmt*/, ...)
{
    // no-op
}

#endif

using namespace std::literals;
using libtransmission::Watchdir;

class Daemon
{
public:
    struct event_base* ev_base_ = nullptr;
    tr_sys_file_t logfile_ = TR_BAD_SYS_FILE;

private:
    bool seen_hup_ = false;
    bool paused_ = false;
    std::string config_dir_;
    char const* log_file_name_ = nullptr;
    tr_session* my_session_ = nullptr;
    tr_variant settings_ = {};
    tr_quark key_pidfile_ = tr_quark_new("pidfile"sv);
    tr_quark key_watch_dir_force_generic_ = tr_quark_new("watch-dir-force-generic"sv);

public:
    Daemon() = default;

    ~Daemon()
    {
        tr_variantClear(&settings_);
    }

    bool init(int argc, char* argv[], bool* foreground, int* ret);
    bool parseArgs(int argc, char const** argv, bool* dump_settings, bool* foreground, int* exit_code);
    bool reopenLogFile(char const* filename);
    int start(bool (*setupsigfn)(void*), bool foreground);
    void periodicUpdate();
    void reportStatus();
    void reconfigure();
    void stop();
};

/***
****
***/

static char constexpr MyName[] = "transmission-daemon";
static char constexpr Usage[] = "Transmission " LONG_VERSION_STRING
                                "  https://transmissionbt.com/\n"
                                "A fast and easy BitTorrent client\n"
                                "\n"
                                "transmission-daemon is a headless Transmission session that can be\n"
                                "controlled via transmission-qt, transmission-remote, or its web interface.\n"
                                "\n"
                                "Usage: transmission-daemon [options]";

static auto constexpr MemK = size_t{ 1024 };
static char constexpr MemKStr[] = "KiB";
static char constexpr MemMStr[] = "MiB";
static char constexpr MemGStr[] = "GiB";
static char constexpr MemTStr[] = "TiB";

static auto constexpr DiskK = size_t{ 1000 };
static char constexpr DiskKStr[] = "kB";
static char constexpr DiskMStr[] = "MB";
static char constexpr DiskGStr[] = "GB";
static char constexpr DiskTStr[] = "TB";

static auto constexpr SpeedK = size_t{ 1000 };
static char constexpr SpeedKStr[] = "kB/s";
static char constexpr SpeedMStr[] = "MB/s";
static char constexpr SpeedGStr[] = "GB/s";
static char constexpr SpeedTStr[] = "TB/s";

/***
****  Config File
***/

static auto constexpr Options = std::array<tr_option, 45>{
    { { 'a', "allowed", "Allowed IP addresses. (Default: " TR_DEFAULT_RPC_WHITELIST ")", "a", true, "<list>" },
      { 'b', "blocklist", "Enable peer blocklists", "b", false, nullptr },
      { 'B', "no-blocklist", "Disable peer blocklists", "B", false, nullptr },
      { 'c', "watch-dir", "Where to watch for new torrent files", "c", true, "<directory>" },
      { 'C', "no-watch-dir", "Disable the watch-dir", "C", false, nullptr },
      { 941, "incomplete-dir", "Where to store new torrents until they're complete", nullptr, true, "<directory>" },
      { 942, "no-incomplete-dir", "Don't store incomplete torrents in a different location", nullptr, false, nullptr },
      { 'd', "dump-settings", "Dump the settings and exit", "d", false, nullptr },
      { 943, "default-trackers", "Trackers for public torrents to use automatically", nullptr, true, "<list>" },
      { 'e', "logfile", "Dump the log messages to this filename", "e", true, "<filename>" },
      { 'f', "foreground", "Run in the foreground instead of daemonizing", "f", false, nullptr },
      { 'g', "config-dir", "Where to look for configuration files", "g", true, "<path>" },
      { 'p', "port", "RPC port (Default: " TR_DEFAULT_RPC_PORT_STR ")", "p", true, "<port>" },
      { 't', "auth", "Require authentication", "t", false, nullptr },
      { 'T', "no-auth", "Don't require authentication", "T", false, nullptr },
      { 'u', "username", "Set username for authentication", "u", true, "<username>" },
      { 'v', "password", "Set password for authentication", "v", true, "<password>" },
      { 'V', "version", "Show version number and exit", "V", false, nullptr },
      { 810, "log-level", "Must be 'critical', 'error', 'warn', 'info', 'debug', or 'trace'.", nullptr, true, "<level>" },
      { 811, "log-error", "Deprecated. Use --log-level=error", nullptr, false, nullptr },
      { 812, "log-info", "Deprecated. Use --log-level=info", nullptr, false, nullptr },
      { 813, "log-debug", "Deprecated. Use --log-level=debug", nullptr, false, nullptr },
      { 'w', "download-dir", "Where to save downloaded data", "w", true, "<path>" },
      { 800, "paused", "Pause all torrents on startup", nullptr, false, nullptr },
      { 'o', "dht", "Enable distributed hash tables (DHT)", "o", false, nullptr },
      { 'O', "no-dht", "Disable distributed hash tables (DHT)", "O", false, nullptr },
      { 'y', "lpd", "Enable local peer discovery (LPD)", "y", false, nullptr },
      { 'Y', "no-lpd", "Disable local peer discovery (LPD)", "Y", false, nullptr },
      { 830, "utp", "Enable uTP for peer connections", nullptr, false, nullptr },
      { 831, "no-utp", "Disable uTP for peer connections", nullptr, false, nullptr },
      { 'P', "peerport", "Port for incoming peers (Default: " TR_DEFAULT_PEER_PORT_STR ")", "P", true, "<port>" },
      { 'm', "portmap", "Enable portmapping via NAT-PMP or UPnP", "m", false, nullptr },
      { 'M', "no-portmap", "Disable portmapping", "M", false, nullptr },
      { 'L',
        "peerlimit-global",
        "Maximum overall number of peers (Default: " TR_DEFAULT_PEER_LIMIT_GLOBAL_STR ")",
        "L",
        true,
        "<limit>" },
      { 'l',
        "peerlimit-torrent",
        "Maximum number of peers per torrent (Default: " TR_DEFAULT_PEER_LIMIT_TORRENT_STR ")",
        "l",
        true,
        "<limit>" },
      { 910, "encryption-required", "Encrypt all peer connections", "er", false, nullptr },
      { 911, "encryption-preferred", "Prefer encrypted peer connections", "ep", false, nullptr },
      { 912, "encryption-tolerated", "Prefer unencrypted peer connections", "et", false, nullptr },
      { 'i', "bind-address-ipv4", "Where to listen for peer connections", "i", true, "<ipv4 addr>" },
      { 'I', "bind-address-ipv6", "Where to listen for peer connections", "I", true, "<ipv6 addr>" },
      { 'r', "rpc-bind-address", "Where to listen for RPC connections", "r", true, "<ip addr>" },
      { 953,
        "global-seedratio",
        "All torrents, unless overridden by a per-torrent setting, should seed until a specific ratio",
        "gsr",
        true,
        "ratio" },
      { 954,
        "no-global-seedratio",
        "All torrents, unless overridden by a per-torrent setting, should seed regardless of ratio",
        "GSR",
        false,
        nullptr },
      { 'x', "pid-file", "Enable PID file", "x", true, "<pid-file>" },
      { 0, nullptr, nullptr, nullptr, false, nullptr } }
};

bool Daemon::reopenLogFile(char const* filename)
{
    tr_error* error = nullptr;
    tr_sys_file_t const old_log_file = logfile_;
    tr_sys_file_t const new_log_file = tr_sys_file_open(
        filename,
        TR_SYS_FILE_WRITE | TR_SYS_FILE_CREATE | TR_SYS_FILE_APPEND,
        0666,
        &error);

    if (new_log_file == TR_BAD_SYS_FILE)
    {
        fprintf(stderr, "Couldn't (re)open log file \"%s\": %s\n", filename, error->message);
        tr_error_free(error);
        return false;
    }

    logfile_ = new_log_file;

    if (old_log_file != TR_BAD_SYS_FILE)
    {
        tr_sys_file_close(old_log_file);
    }

    return true;
}

static std::string getConfigDir(int argc, char const* const* argv)
{
    int c;
    char const* optstr;
    int const ind = tr_optind;

    while ((c = tr_getopt(Usage, argc, argv, std::data(Options), &optstr)) != TR_OPT_DONE)
    {
        if (c == 'g')
        {
            return optstr;
        }
    }

    tr_optind = ind;

    return tr_getDefaultConfigDir(MyName);
}

static auto onFileAdded(tr_session* session, std::string_view dirname, std::string_view basename)
{
    auto const lowercase = tr_strlower(basename);
    auto const is_torrent = tr_strvEndsWith(lowercase, ".torrent"sv);
    auto const is_magnet = tr_strvEndsWith(lowercase, ".magnet"sv);

    if (!is_torrent && !is_magnet)
    {
        return Watchdir::Action::Done;
    }

    auto const filename = tr_pathbuf{ dirname, '/', basename };
    tr_ctor* const ctor = tr_ctorNew(session);

    bool retry = false;

    if (is_torrent)
    {
        if (!tr_ctorSetMetainfoFromFile(ctor, filename, nullptr))
        {
            retry = true;
        }
    }
    else // is_magnet
    {
        auto content = std::vector<char>{};
        tr_error* error = nullptr;
        if (!tr_loadFile(filename, content, &error))
        {
            tr_logAddWarn(fmt::format(
                _("Couldn't read '{path}': {error} ({error_code})"),
                fmt::arg("path", basename),
                fmt::arg("error", error->message),
                fmt::arg("error_code", error->code)));
            tr_error_free(error);
            retry = true;
        }
        else
        {
            content.push_back('\0'); // zero-terminated string
            auto const* data = std::data(content);
            if (!tr_ctorSetMetainfoFromMagnetLink(ctor, data, nullptr))
            {
                retry = true;
            }
        }
    }

    if (retry)
    {
        tr_ctorFree(ctor);
        return Watchdir::Action::Retry;
    }

    if (tr_torrentNew(ctor, nullptr) == nullptr)
    {
        tr_logAddError(fmt::format(_("Couldn't add torrent file '{path}'"), fmt::arg("path", basename)));
    }
    else
    {
        bool trash = false;
        bool const test = tr_ctorGetDeleteSource(ctor, &trash);

        if (test && trash)
        {
            tr_error* error = nullptr;

            tr_logAddInfo(fmt::format(_("Removing torrent file '{path}'"), fmt::arg("path", basename)));

            if (!tr_sys_path_remove(filename, &error))
            {
                tr_logAddError(fmt::format(
                    _("Couldn't remove '{path}': {error} ({error_code})"),
                    fmt::arg("path", basename),
                    fmt::arg("error", error->message),
                    fmt::arg("error_code", error->code)));
                tr_error_free(error);
            }
        }
        else
        {
            tr_sys_path_rename(filename, tr_pathbuf{ filename, ".added"sv });
        }
    }

    tr_ctorFree(ctor);
    return Watchdir::Action::Done;
}

static char const* levelName(tr_log_level level)
{
    switch (level)
    {
    case TR_LOG_CRITICAL:
        return "CRT";
    case TR_LOG_ERROR:
        return "ERR";
    case TR_LOG_WARN:
        return "WRN";
    case TR_LOG_DEBUG:
        return "dbg";
    case TR_LOG_TRACE:
        return "trc";
    default:
        return "inf";
    }
}

static void printMessage(
    tr_sys_file_t file,
    tr_log_level level,
    std::string_view name,
    std::string_view message,
    std::string_view filename,
    int line)
{
    auto const out = std::empty(name) ? fmt::format(FMT_STRING("{:s} ({:s}:{:d})"), message, filename, line) :
                                        fmt::format(FMT_STRING("{:s} {:s} ({:s}:{:d})"), name, message, filename, line);

    if (file != TR_BAD_SYS_FILE)
    {
        auto timestr = std::array<char, 64>{};
        tr_logGetTimeStr(std::data(timestr), std::size(timestr));
        tr_sys_file_write_line(file, fmt::format(FMT_STRING("[{:s}] {:s} {:s}"), std::data(timestr), levelName(level), out));
    }

#ifdef HAVE_SYSLOG

    else /* daemon... write to syslog */
    {
        int priority;

        /* figure out the syslog priority */
        switch (level)
        {
        case TR_LOG_CRITICAL:
            priority = LOG_CRIT;
            break;

        case TR_LOG_ERROR:
            priority = LOG_ERR;
            break;

        case TR_LOG_WARN:
            priority = LOG_WARNING;
            break;

        case TR_LOG_INFO:
            priority = LOG_INFO;
            break;

        default:
            priority = LOG_DEBUG;
            break;
        }

        syslog(priority, "%s", out.c_str());
    }

#endif
}

static void pumpLogMessages(tr_sys_file_t file)
{
    tr_log_message* list = tr_logGetQueue();

    for (tr_log_message const* l = list; l != nullptr; l = l->next)
    {
        printMessage(file, l->level, l->name, l->message, l->file, l->line);
    }

    if (file != TR_BAD_SYS_FILE)
    {
        tr_sys_file_flush(file);
    }

    tr_logFreeQueue(list);
}

void Daemon::reportStatus(void)
{
    double const up = tr_sessionGetRawSpeed_KBps(my_session_, TR_UP);
    double const dn = tr_sessionGetRawSpeed_KBps(my_session_, TR_DOWN);

    if (up > 0 || dn > 0)
    {
        sd_notifyf(0, "STATUS=Uploading %.2f KBps, Downloading %.2f KBps.\n", up, dn);
    }
    else
    {
        sd_notify(0, "STATUS=Idle.\n");
    }
}

void Daemon::periodicUpdate(void)
{
    pumpLogMessages(logfile_);
    reportStatus();
}

static void periodicUpdate(evutil_socket_t /*fd*/, short /*what*/, void* arg)
{
    static_cast<Daemon*>(arg)->periodicUpdate();
}

static tr_rpc_callback_status on_rpc_callback(
    tr_session* /*session*/,
    tr_rpc_callback_type type,
    tr_torrent* /*tor*/,
    void* arg)
{
    Daemon* daemon = static_cast<Daemon*>(arg);

    if (type == TR_RPC_SESSION_CLOSE)
    {
        event_base_loopexit(daemon->ev_base_, nullptr);
    }

    return TR_RPC_OK;
}

bool Daemon::parseArgs(int argc, char const** argv, bool* dump_settings, bool* foreground, int* exit_code)
{
    int c;
    char const* optstr;

    paused_ = false;
    *dump_settings = false;
    *foreground = false;

    tr_optind = 1;

    while ((c = tr_getopt(Usage, argc, argv, std::data(Options), &optstr)) != TR_OPT_DONE)
    {
        switch (c)
        {
        case 'a':
            tr_variantDictAddStr(&settings_, TR_KEY_rpc_whitelist, optstr);
            tr_variantDictAddBool(&settings_, TR_KEY_rpc_whitelist_enabled, true);
            break;

        case 'b':
            tr_variantDictAddBool(&settings_, TR_KEY_blocklist_enabled, true);
            break;

        case 'B':
            tr_variantDictAddBool(&settings_, TR_KEY_blocklist_enabled, false);
            break;

        case 'c':
            tr_variantDictAddStr(&settings_, TR_KEY_watch_dir, optstr);
            tr_variantDictAddBool(&settings_, TR_KEY_watch_dir_enabled, true);
            break;

        case 'C':
            tr_variantDictAddBool(&settings_, TR_KEY_watch_dir_enabled, false);
            break;

        case 941:
            tr_variantDictAddStr(&settings_, TR_KEY_incomplete_dir, optstr);
            tr_variantDictAddBool(&settings_, TR_KEY_incomplete_dir_enabled, true);
            break;

        case 942:
            tr_variantDictAddBool(&settings_, TR_KEY_incomplete_dir_enabled, false);
            break;

        case 943:
            tr_variantDictAddStr(&settings_, TR_KEY_default_trackers, optstr);
            break;

        case 'd':
            *dump_settings = true;
            break;

        case 'e':
            if (reopenLogFile(optstr))
            {
                log_file_name_ = optstr;
            }

            break;

        case 'f':
            *foreground = true;
            break;

        case 'g': /* handled above */
            break;

        case 'V': /* version */
            fprintf(stderr, "%s %s\n", MyName, LONG_VERSION_STRING);
            *exit_code = 0;
            return false;

        case 'o':
            tr_variantDictAddBool(&settings_, TR_KEY_dht_enabled, true);
            break;

        case 'O':
            tr_variantDictAddBool(&settings_, TR_KEY_dht_enabled, false);
            break;

        case 'p':
            tr_variantDictAddInt(&settings_, TR_KEY_rpc_port, atoi(optstr));
            break;

        case 't':
            tr_variantDictAddBool(&settings_, TR_KEY_rpc_authentication_required, true);
            break;

        case 'T':
            tr_variantDictAddBool(&settings_, TR_KEY_rpc_authentication_required, false);
            break;

        case 'u':
            tr_variantDictAddStr(&settings_, TR_KEY_rpc_username, optstr);
            break;

        case 'v':
            tr_variantDictAddStr(&settings_, TR_KEY_rpc_password, optstr);
            break;

        case 'w':
            tr_variantDictAddStr(&settings_, TR_KEY_download_dir, optstr);
            break;

        case 'P':
            tr_variantDictAddInt(&settings_, TR_KEY_peer_port, atoi(optstr));
            break;

        case 'm':
            tr_variantDictAddBool(&settings_, TR_KEY_port_forwarding_enabled, true);
            break;

        case 'M':
            tr_variantDictAddBool(&settings_, TR_KEY_port_forwarding_enabled, false);
            break;

        case 'L':
            tr_variantDictAddInt(&settings_, TR_KEY_peer_limit_global, atoi(optstr));
            break;

        case 'l':
            tr_variantDictAddInt(&settings_, TR_KEY_peer_limit_per_torrent, atoi(optstr));
            break;

        case 800:
            paused_ = true;
            break;

        case 910:
            tr_variantDictAddInt(&settings_, TR_KEY_encryption, TR_ENCRYPTION_REQUIRED);
            break;

        case 911:
            tr_variantDictAddInt(&settings_, TR_KEY_encryption, TR_ENCRYPTION_PREFERRED);
            break;

        case 912:
            tr_variantDictAddInt(&settings_, TR_KEY_encryption, TR_CLEAR_PREFERRED);
            break;

        case 'i':
            tr_variantDictAddStr(&settings_, TR_KEY_bind_address_ipv4, optstr);
            break;

        case 'I':
            tr_variantDictAddStr(&settings_, TR_KEY_bind_address_ipv6, optstr);
            break;

        case 'r':
            tr_variantDictAddStr(&settings_, TR_KEY_rpc_bind_address, optstr);
            break;

        case 953:
            tr_variantDictAddReal(&settings_, TR_KEY_ratio_limit, atof(optstr));
            tr_variantDictAddBool(&settings_, TR_KEY_ratio_limit_enabled, true);
            break;

        case 954:
            tr_variantDictAddBool(&settings_, TR_KEY_ratio_limit_enabled, false);
            break;

        case 'x':
            tr_variantDictAddStr(&settings_, key_pidfile_, optstr);
            break;

        case 'y':
            tr_variantDictAddBool(&settings_, TR_KEY_lpd_enabled, true);
            break;

        case 'Y':
            tr_variantDictAddBool(&settings_, TR_KEY_lpd_enabled, false);
            break;

        case 810:
            if (auto const level = tr_logGetLevelFromKey(optstr); level)
            {
                tr_variantDictAddInt(&settings_, TR_KEY_message_level, *level);
            }
            else
            {
                std::cerr << fmt::format(_("Couldn't parse log level '{level}'"), fmt::arg("level", optstr)) << std::endl;
            }
            break;

        case 811:
            std::cerr << "WARN: --log-error is deprecated. Use --log-level=error" << std::endl;
            tr_variantDictAddInt(&settings_, TR_KEY_message_level, TR_LOG_ERROR);
            break;

        case 812:
            std::cerr << "WARN: --log-info is deprecated. Use --log-level=info" << std::endl;
            tr_variantDictAddInt(&settings_, TR_KEY_message_level, TR_LOG_INFO);
            break;

        case 813:
            std::cerr << "WARN: --log-debug is deprecated. Use --log-level=debug" << std::endl;
            tr_variantDictAddInt(&settings_, TR_KEY_message_level, TR_LOG_DEBUG);
            break;

        case 830:
            tr_variantDictAddBool(&settings_, TR_KEY_utp_enabled, true);
            break;

        case 831:
            tr_variantDictAddBool(&settings_, TR_KEY_utp_enabled, false);
            break;

        default:
            tr_getopt_usage(MyName, Usage, std::data(Options));
            *exit_code = 0;
            return false;
        }
    }

    return true;
}

static void daemon_reconfigure(void* arg)
{
    static_cast<Daemon*>(arg)->reconfigure();
}

void Daemon::reconfigure(void)
{
    if (my_session_ == nullptr)
    {
        tr_logAddInfo(_("Deferring reload until session is fully started."));
        seen_hup_ = true;
    }
    else
    {
        tr_variant newsettings;
        char const* configDir;

        /* reopen the logfile to allow for log rotation */
        if (log_file_name_ != nullptr)
        {
            reopenLogFile(log_file_name_);
        }

        configDir = tr_sessionGetConfigDir(my_session_);
        tr_logAddInfo(fmt::format(_("Reloading settings from '{path}'"), fmt::arg("path", configDir)));
        tr_variantInitDict(&newsettings, 0);
        tr_variantDictAddBool(&newsettings, TR_KEY_rpc_enabled, true);
        tr_sessionLoadSettings(&newsettings, configDir, MyName);
        tr_sessionSet(my_session_, &newsettings);
        tr_variantClear(&newsettings);
        tr_sessionReloadBlocklists(my_session_);
    }
}

static void daemon_stop(void* arg)
{
    static_cast<Daemon*>(arg)->stop();
}

void Daemon::stop(void)
{
    event_base_loopexit(ev_base_, nullptr);
}

int Daemon::start(bool (*setupsigfn)(void*), bool foreground)
{
    bool boolVal;
    bool pidfile_created = false;
    tr_session* session = nullptr;
    struct event* status_ev = nullptr;
    auto watchdir = std::unique_ptr<Watchdir>{};
    char const* const cdir = this->config_dir_.c_str();

    sd_notifyf(0, "MAINPID=%d\n", (int)getpid());

    /* should go before libevent calls */
    tr_net_init();

    /* setup event state */
    ev_base_ = event_base_new();

    if (ev_base_ == nullptr || (setupsigfn ? setupsigfn(ev_base_) : true) == false)
    {
        auto const error_code = errno;
        auto const errmsg = fmt::format(
            _("Couldn't initialize daemon: {error} ({error_code})"),
            fmt::arg("error", tr_strerror(error_code)),
            fmt::arg("error_code", error_code));
        printMessage(logfile_, TR_LOG_ERROR, MyName, errmsg, __FILE__, __LINE__);
        return 1;
    }

    /* start the session */
    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);
    session = tr_sessionInit(cdir, true, &settings_);
    tr_sessionSetRPCCallback(session, on_rpc_callback, this);
    tr_logAddInfo(fmt::format(_("Loading settings from '{path}'"), fmt::arg("path", cdir)));
    tr_sessionSaveSettings(session, cdir, &settings_);

    auto sv = std::string_view{};
    (void)tr_variantDictFindStrView(&settings_, key_pidfile_, &sv);
    auto const sz_pid_filename = std::string{ sv };
    if (!std::empty(sz_pid_filename))
    {
        tr_error* error = nullptr;
        tr_sys_file_t fp = tr_sys_file_open(
            sz_pid_filename.c_str(),
            TR_SYS_FILE_WRITE | TR_SYS_FILE_CREATE | TR_SYS_FILE_TRUNCATE,
            0666,
            &error);

        if (fp != TR_BAD_SYS_FILE)
        {
            auto const out = std::to_string(getpid());
            tr_sys_file_write(fp, std::data(out), std::size(out), nullptr);
            tr_sys_file_close(fp);
            tr_logAddInfo(fmt::format(_("Saved pidfile '{path}'"), fmt::arg("path", sz_pid_filename)));
            pidfile_created = true;
        }
        else
        {
            tr_logAddError(fmt::format(
                _("Couldn't save '{path}': {error} ({error_code})"),
                fmt::arg("path", sz_pid_filename),
                fmt::arg("error", error->message),
                fmt::arg("error_code", error->code)));
            tr_error_free(error);
        }
    }

    if (tr_variantDictFindBool(&settings_, TR_KEY_rpc_authentication_required, &boolVal) && boolVal)
    {
        tr_logAddInfo(_("Requiring authentication"));
    }

    my_session_ = session;

    /* If we got a SIGHUP during startup, process that now. */
    if (seen_hup_)
    {
        daemon_reconfigure(this);
    }

    /* maybe add a watchdir */
    if (tr_variantDictFindBool(&settings_, TR_KEY_watch_dir_enabled, &boolVal) && boolVal)
    {
        auto force_generic = bool{ false };
        (void)tr_variantDictFindBool(&settings_, key_watch_dir_force_generic_, &force_generic);

        auto dir = std::string_view{};
        (void)tr_variantDictFindStrView(&settings_, TR_KEY_watch_dir, &dir);
        if (!std::empty(dir))
        {
            tr_logAddInfo(fmt::format(_("Watching '{path}' for new torrent files"), fmt::arg("path", dir)));

            auto handler = [session](std::string_view dirname, std::string_view basename)
            {
                return onFileAdded(session, dirname, basename);
            };

            auto timer_maker = libtransmission::EvTimerMaker{ ev_base_ };
            watchdir = force_generic ? Watchdir::createGeneric(dir, handler, timer_maker) :
                                       Watchdir::create(dir, handler, timer_maker, ev_base_);
        }
    }

    /* load the torrents */
    {
        tr_ctor* ctor = tr_ctorNew(my_session_);

        if (paused_)
        {
            tr_ctorSetPaused(ctor, TR_FORCE, true);
        }

        tr_sessionLoadTorrents(my_session_, ctor);
        tr_ctorFree(ctor);
    }

#ifdef HAVE_SYSLOG

    if (!foreground)
    {
        openlog(MyName, LOG_CONS | LOG_PID, LOG_DAEMON);
    }

#endif

    /* Create new timer event to report daemon status */
    {
        constexpr auto one_sec = timeval{ 1, 0 }; // 1 second
        status_ev = event_new(ev_base_, -1, EV_PERSIST, &::periodicUpdate, this);

        if (status_ev == nullptr)
        {
            auto const error_code = errno;
            tr_logAddError(fmt::format(
                _("Couldn't create event: {error} ({error_code})"),
                fmt::arg("error", tr_strerror(error_code)),
                fmt::arg("error_code", error_code)));
            goto CLEANUP;
        }

        if (event_add(status_ev, &one_sec) == -1)
        {
            auto const error_code = errno;
            tr_logAddError(fmt::format(
                _("Couldn't add event: {error} ({error_code})"),
                fmt::arg("error", tr_strerror(error_code)),
                fmt::arg("error_code", error_code)));
            goto CLEANUP;
        }
    }

    sd_notify(0, "READY=1\n");

    /* Run daemon event loop */
    if (event_base_dispatch(ev_base_) == -1)
    {
        auto const error_code = errno;
        tr_logAddError(fmt::format(
            _("Couldn't launch daemon event loop: {error} ({error_code})"),
            fmt::arg("error", tr_strerror(error_code)),
            fmt::arg("error_code", error_code)));
        goto CLEANUP;
    }

CLEANUP:
    sd_notify(0, "STATUS=Closing transmission session...\n");
    printf("Closing transmission session...");

    watchdir.reset();

    if (status_ev != nullptr)
    {
        event_del(status_ev);
        event_free(status_ev);
    }

    event_base_free(ev_base_);

    tr_sessionSaveSettings(my_session_, cdir, &settings_);
    tr_sessionClose(my_session_);
    pumpLogMessages(logfile_);
    printf(" done.\n");

    /* shutdown */
#ifdef HAVE_SYSLOG

    if (!foreground)
    {
        syslog(LOG_INFO, "%s", "Closing session");
        closelog();
    }

#endif

    /* cleanup */
    if (pidfile_created)
    {
        tr_sys_path_remove(sz_pid_filename);
    }

    sd_notify(0, "STATUS=\n");

    return 0;
}

static int daemon_start(void* varg, bool (*setupsigfn)(void*), bool foreground)
{
    return static_cast<Daemon*>(varg)->start(setupsigfn, foreground);
}

bool Daemon::init(int argc, char* argv[], bool* foreground, int* ret)
{
    config_dir_ = getConfigDir(argc, (char const* const*)argv);

    /* load settings from defaults + config file */
    tr_variantInitDict(&settings_, 0);
    tr_variantDictAddBool(&settings_, TR_KEY_rpc_enabled, true);
    bool const loaded = tr_sessionLoadSettings(&settings_, config_dir_.c_str(), MyName);

    bool dumpSettings;

    *ret = 0;

    /* overwrite settings from the command line */
    if (!parseArgs(argc, (char const**)argv, &dumpSettings, foreground, ret))
    {
        goto EXIT_EARLY;
    }

    if (*foreground && logfile_ == TR_BAD_SYS_FILE)
    {
        logfile_ = tr_sys_file_get_std(TR_STD_SYS_FILE_ERR);
    }

    if (!loaded)
    {
        printMessage(logfile_, TR_LOG_ERROR, MyName, "Error loading config file -- exiting.", __FILE__, __LINE__);
        *ret = 1;
        goto EXIT_EARLY;
    }

    if (dumpSettings)
    {
        auto const str = tr_variantToStr(&settings_, TR_VARIANT_FMT_JSON);
        fprintf(stderr, "%s", str.c_str());
        goto EXIT_EARLY;
    }

    return true;

EXIT_EARLY:
    tr_variantClear(&settings_);
    return false;
}

int tr_main(int argc, char* argv[])
{
    Daemon daemon;
    bool foreground;
    int ret;

    if (!daemon.init(argc, argv, &foreground, &ret))
    {
        return ret;
    }

    auto constexpr cb = dtr_callbacks{
        &daemon_start,
        &daemon_stop,
        &daemon_reconfigure,
    };

    if (tr_error* error = nullptr; !dtr_daemon(&cb, &daemon, foreground, &ret, &error))
    {
        auto const errmsg = fmt::format(FMT_STRING("Couldn't daemonize: {:s} ({:d})"), error->message, error->code);
        printMessage(daemon.logfile_, TR_LOG_ERROR, MyName, errmsg, __FILE__, __LINE__);
        tr_error_free(error);
    }

    return ret;
}