transmission/libtransmission/transmission.h

// This file Copyright © Transmission authors and contributors.
// It may be used under the 3-Clause BSD (SPDX: BSD-3-Clause),
// 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.

// This file defines the public API for the libtransmission library.

#pragma once

// --- Basic Types

#include <array>
#include <cstddef>
#include <cstdint>
#include <ctime>
#include <functional>
#include <optional>
#include <string>
#include <string_view>
#include <vector>

#include "libtransmission/constants.h"
#include "libtransmission/types.h"
#include "libtransmission/values.h"

// --- Startup & Shutdown

/**
 * @addtogroup tr_session Session
 *
 * A libtransmission session is created by calling `tr_sessionInit()`.
 * libtransmission creates a thread for itself so that it can operate
 * independently of the caller's event loop. The session will continue
 * until `tr_sessionClose()` is called.
 *
 * @{
 */

/**
 * @brief get Transmission's default configuration file directory.
 *
 * The default configuration directory is determined this way:
 * -# If the `TRANSMISSION_HOME` environment variable is set, its value is used.
 * -# On Darwin, `"${HOME}/Library/Application Support/${appname}"` is used.
 * -# On Windows, `"${CSIDL_APPDATA}/${appname}"` is used.
 * -# If `XDG_CONFIG_HOME` is set, `"${XDG_CONFIG_HOME}/${appname}"` is used.
 * -# `"${HOME}/.config/${appname}"` is used as a last resort.
 */
[[nodiscard]] std::string tr_getDefaultConfigDir(std::string_view appname);

/**
 * @brief returns Transmission's default download directory.
 *
 * The default download directory is determined this way:
 * -# If the `HOME` environment variable is set, `"${HOME}/Downloads"` is used.
 * -# On Windows, `"${CSIDL_MYDOCUMENTS}/Downloads"` is used.
 * -# Otherwise, `getpwuid(getuid())->pw_dir + "/Downloads"` is used.
 */
[[nodiscard]] std::string tr_getDefaultDownloadDir();

/**
 * Add libtransmission's default settings to the benc dictionary.
 *
 * Example:
 * @code
 *     int64_t i;
 *
 *     auto settings = tr_sessionGetDefaultSettings();
 *     if (tr_variantDictFindInt(&settings, TR_PREFS_KEY_PEER_PORT, &i))
 *         fprintf(stderr, "the default peer port is %d\n", (int)i);
 * @endcode
 *
 * @return a variant map of the default settinggs
 * @see `tr_sessionLoadSettings()`
 * @see `tr_sessionInit()`
 * @see `tr_getDefaultConfigDir()`
 */
tr_variant tr_sessionGetDefaultSettings();

/**
 * Add the session's current configuration settings to the benc dictionary.
 *
 * TODO: if we ever make libtransmissionapp, this would go there.
 *
 * @return a variant map of the session's current settings
 * @param session the session to query
 * @see `tr_sessionGetDefaultSettings()`
 */
tr_variant tr_sessionGetSettings(tr_session const* session);

/**
 * Load settings from the configuration directory's settings.json file,
 * using libtransmission's default settings as fallbacks for missing keys.
 *
 * TODO: if we ever make libtransmissionapp, this would go there.
 *
 * @param config_dir the configuration directory to find settings.json
 * @param app_defaults optional tr_variant containing the app-specific defaults
 * @return the loaded settings
 * @see `tr_sessionGetDefaultSettings()`
 * @see `tr_sessionInit()`
 * @see `tr_sessionSaveSettings()`
 */
[[nodiscard]] tr_variant tr_sessionLoadSettings(std::string_view config_dir, tr_variant const* app_defaults = nullptr);

/**
 * Add the session's configuration settings to the benc dictionary
 * and save it to the configuration directory's settings.json file.
 *
 * TODO: if we ever make libtransmissionapp, this would go there.
 *
 * @param session    the session to save
 * @param config_dir  the directory to write to
 * @param client_settings the dictionary to save
 * @see `tr_sessionLoadSettings()`
 */
void tr_sessionSaveSettings(tr_session* session, std::string_view config_dir, tr_variant const& client_settings);

/**
 * @brief Initialize a libtransmission session.
 *
 * For example, this will instantiate a session with all the default values:
 * @code
 *     auto settings = tr_sessionGetDefaultSettings();
 *     char const* const configDir = tr_getDefaultConfigDir("Transmission");
 *     tr_session* const session = tr_sessionInit(configDir, true, &settings);
 * @endcode
 *
 * @param config_dir where Transmission will look for resume files, blocklists, etc.
 * @param message_queueing_enabled if false, messages will be dumped to stderr
 * @param settings libtransmission settings
 * @see `tr_sessionGetDefaultSettings()`
 * @see `tr_sessionLoadSettings()`
 * @see `tr_getDefaultConfigDir()`
 */
tr_session* tr_sessionInit(std::string_view config_dir, bool message_queueing_enabled, tr_variant const& settings);

/** @brief Update a session's settings from a benc dictionary
           like to the one used in `tr_sessionInit()` */
void tr_sessionSet(tr_session* session, tr_variant const& settings);

/** @brief Rescan the blocklists directory and
           reload whatever blocklist files are found there */
void tr_sessionReloadBlocklists(tr_session* session);

/**
 * @brief End a libtransmission session.
 * @see `tr_sessionInit()`
 *
 * This may take some time while &event=stopped announces are sent to trackers.
 *
 * @param timeout_secs specifies how long to wait on these announces.
 */
void tr_sessionClose(tr_session* session, double timeout_secs = 15.0);

/**
 * @brief Return the session's configuration directory.
 *
 * This is where transmission stores its torrent files, .resume files,
 * blocklists, etc. It's set in `tr_transmissionInit()`.
 */
[[nodiscard]] std::string tr_sessionGetConfigDir(tr_session const* session);

/**
 * @brief Get the default download folder for new torrents.
 *
 * This is set by `tr_sessionInit()` or `tr_sessionSetDownloadDir()`,
 * and can be overridden on a per-torrent basis by `tr_ctorSetDownloadDir()`.
 */
[[nodiscard]] std::string tr_sessionGetDownloadDir(tr_session const* session);

/**
 * @brief Set the per-session default download folder for new torrents.
 * @see `tr_sessionInit()`
 * @see `tr_sessionGetDownloadDir()`
 * @see `tr_ctorSetDownloadDir()`
 */
void tr_sessionSetDownloadDir(tr_session* session, std::string_view download_dir);

/** @brief get the per-session incomplete download folder */
[[nodiscard]] std::string tr_sessionGetIncompleteDir(tr_session const* session);

/**
 * @brief set the per-session incomplete download folder.
 *
 * When you add a new torrent and the session's incomplete directory is enabled,
 * the new torrent will start downloading into that directory, and then be moved
 * to `tr_torrent.downloadDir` when the torrent is finished downloading.
 *
 * Torrents aren't moved as a result of changing the session's incomplete dir --
 * it's applied to new torrents, not existing ones.
 *
 * `tr_torrentSetLocation()` overrules the incomplete dir: when a user specifies
 * a new location, that becomes the torrent's new `download_dir` and the torrent
 * is moved there immediately regardless of whether or not it's complete.
 *
 * @see `tr_sessionInit()`
 * @see `tr_sessionGetIncompleteDir()`
 * @see `tr_sessionSetIncompleteDirEnabled()`
 * @see `tr_sessionGetIncompleteDirEnabled()`
 */
void tr_sessionSetIncompleteDir(tr_session* session, std::string_view dir);

/** @brief get whether or not the incomplete download folder is enabled */
bool tr_sessionIsIncompleteDirEnabled(tr_session const* session);

/** @brief enable or disable use of the incomplete download folder */
void tr_sessionSetIncompleteDirEnabled(tr_session* session, bool enabled);

/** @brief return true if files will end in ".part" until they're complete */
bool tr_sessionIsIncompleteFileNamingEnabled(tr_session const* session);

/**
 * @brief When enabled, newly-created files will have ".part" appended
 *        to their filename until the file is fully downloaded
 *
 * This is not retroactive -- toggling this will not rename existing files.
 * It only applies to new files created by Transmission after this API call.
 *
 * @see `tr_sessionIsIncompleteFileNamingEnabled()`
 */
void tr_sessionSetIncompleteFileNamingEnabled(tr_session* session, bool enabled);

/** @brief Get whether or not RPC calls are allowed in this session.
    @see `tr_sessionInit()`
    @see `tr_sessionSetRPCEnabled()` */
bool tr_sessionIsRPCEnabled(tr_session const* session);

/**
 * @brief Set whether or not RPC calls are allowed in this session.
 *
 * @details If true, libtransmission will open a server socket to listen
 * for incoming http RPC requests as described in docs/rpc-spec.md.
 *
 * This is initially set by `tr_sessionInit()` and can be
 * queried by `tr_sessionIsRPCEnabled()`.
 */
void tr_sessionSetRPCEnabled(tr_session* session, bool is_enabled);

/** @brief Get which port to listen for RPC requests on.
    @see `tr_sessionInit()`
    @see `tr_sessionSetRPCPort` */
uint16_t tr_sessionGetRPCPort(tr_session const* session);

/** @brief Specify which port to listen for RPC requests on.
    @see `tr_sessionInit()`
    @see `tr_sessionGetRPCPort` */
void tr_sessionSetRPCPort(tr_session* session, uint16_t port);

/** @brief get the Access Control List for allowing/denying RPC requests.
    @return a comma-separated string of whitelist domains.
    @see `tr_sessionInit`
    @see `tr_sessionSetRPCWhitelist` */
[[nodiscard]] std::string tr_sessionGetRPCWhitelist(tr_session const* session);

/**
 * @brief Specify a whitelist for remote RPC access
 *
 * The whitelist is a comma-separated list of dotted-quad IP addresses
 * to be allowed. Wildmat notation is supported, meaning that
 * `'?'` is interpreted as a single-character wildcard and
 * `'*'` is interpreted as a multi-character wildcard.
 */
void tr_sessionSetRPCWhitelist(tr_session* session, std::string_view whitelist);

bool tr_sessionGetRPCWhitelistEnabled(tr_session const* session);
void tr_sessionSetRPCWhitelistEnabled(tr_session* session, bool is_enabled);

// TODO(ckerr): rename function to indicate it returns the salted value
/** @brief get the salted version of the password used to restrict RPC requests.
    @return the password string.
    @see `tr_sessionInit()`
    @see `tr_sessionSetRPCPassword()` */
[[nodiscard]] std::string tr_sessionGetRPCPassword(tr_session const* session);
void tr_sessionSetRPCPassword(tr_session* session, std::string_view password);

[[nodiscard]] std::string tr_sessionGetRPCUsername(tr_session const* session);
void tr_sessionSetRPCUsername(tr_session* session, std::string_view username);

bool tr_sessionIsRPCPasswordEnabled(tr_session const* session);
void tr_sessionSetRPCPasswordEnabled(tr_session* session, bool is_enabled);

void tr_sessionSetDefaultTrackers(tr_session* session, std::string_view trackers);

/**
 * Register to be notified whenever something is changed via RPC,
 * such as a torrent being added, removed, started, stopped, etc.
 *
 * func is invoked FROM LIBTRANSMISSION'S THREAD!
 * This means func must be fast (to avoid blocking peers),
 * shouldn't call libtransmission functions (to avoid deadlock),
 * and shouldn't modify client-level memory without using a mutex!
 */
void tr_sessionSetRPCCallback(tr_session* session, tr_rpc_func func);

// ---

/** @brief Get bandwidth use statistics for the current session */
tr_session_stats tr_sessionGetStats(tr_session const* session);

/** @brief Get cumulative bandwidth statistics for current and past sessions */
tr_session_stats tr_sessionGetCumulativeStats(tr_session const* session);

void tr_sessionClearStats(tr_session* session);

/**
 * @brief Set whether or not torrents are allowed to do peer exchanges.
 *
 * PEX is always disabled in private torrents regardless of this.
 * In public torrents, PEX is enabled by default.
 */
bool tr_sessionIsPexEnabled(tr_session const* session);
void tr_sessionSetPexEnabled(tr_session* session, bool is_enabled);

bool tr_sessionIsDHTEnabled(tr_session const* session);
void tr_sessionSetDHTEnabled(tr_session* session, bool is_enabled);

bool tr_sessionIsUTPEnabled(tr_session const* session);
void tr_sessionSetUTPEnabled(tr_session* session, bool is_enabled);

bool tr_sessionIsLPDEnabled(tr_session const* session);
void tr_sessionSetLPDEnabled(tr_session* session, bool is_enabled);

tr_encryption_mode tr_sessionGetEncryption(tr_session const* session);
void tr_sessionSetEncryption(tr_session* session, tr_encryption_mode mode);

// --- Incoming Peer Connections Port

bool tr_sessionIsPortForwardingEnabled(tr_session const* session);
void tr_sessionSetPortForwardingEnabled(tr_session* session, bool enabled);

uint16_t tr_sessionGetPeerPort(tr_session const* session);
void tr_sessionSetPeerPort(tr_session* session, uint16_t port);

uint16_t tr_sessionSetPeerPortRandom(tr_session* session);

bool tr_sessionGetPeerPortRandomOnStart(tr_session const* session);
void tr_sessionSetPeerPortRandomOnStart(tr_session* session, bool random);

tr_port_forwarding_state tr_sessionGetPortForwarding(tr_session const* session);

// --- Session primary speed limits

size_t tr_sessionGetSpeedLimit_KBps(tr_session const* session, tr_direction dir);
void tr_sessionSetSpeedLimit_KBps(tr_session* session, tr_direction dir, size_t limit_kbyps);

bool tr_sessionIsSpeedLimited(tr_session const* session, tr_direction dir);
void tr_sessionLimitSpeed(tr_session* session, tr_direction dir, bool limited);

// --- Session alt speed limits

size_t tr_sessionGetAltSpeed_KBps(tr_session const* session, tr_direction dir);
void tr_sessionSetAltSpeed_KBps(tr_session* session, tr_direction dir, size_t limit_kbyps);

bool tr_sessionUsesAltSpeed(tr_session const* session);
void tr_sessionUseAltSpeed(tr_session* session, bool enabled);

bool tr_sessionUsesAltSpeedTime(tr_session const* session);
void tr_sessionUseAltSpeedTime(tr_session* session, bool enabled);

size_t tr_sessionGetAltSpeedBegin(tr_session const* session);
void tr_sessionSetAltSpeedBegin(tr_session* session, size_t minutes_since_midnight);

size_t tr_sessionGetAltSpeedEnd(tr_session const* session);
void tr_sessionSetAltSpeedEnd(tr_session* session, size_t minutes_since_midnight);

tr_sched_day tr_sessionGetAltSpeedDay(tr_session const* session);
void tr_sessionSetAltSpeedDay(tr_session* session, tr_sched_day day);

void tr_sessionSetAltSpeedFunc(tr_session* session, tr_altSpeedFunc func);

// ---

double tr_sessionGetRawSpeed_KBps(tr_session const* session, tr_direction dir);

bool tr_sessionIsRatioLimited(tr_session const* session);
void tr_sessionSetRatioLimited(tr_session* session, bool is_limited);

double tr_sessionGetRatioLimit(tr_session const* session);
void tr_sessionSetRatioLimit(tr_session* session, double desired_ratio);

bool tr_sessionIsIdleLimited(tr_session const* session);
void tr_sessionSetIdleLimited(tr_session* session, bool is_limited);

uint16_t tr_sessionGetIdleLimit(tr_session const* session);
void tr_sessionSetIdleLimit(tr_session* session, uint16_t idle_minutes);

uint16_t tr_sessionGetPeerLimit(tr_session const* session);
void tr_sessionSetPeerLimit(tr_session* session, uint16_t max_global_peers);

uint16_t tr_sessionGetPeerLimitPerTorrent(tr_session const* session);
void tr_sessionSetPeerLimitPerTorrent(tr_session* session, uint16_t max_peers);

bool tr_sessionGetPaused(tr_session const* session);
void tr_sessionSetPaused(tr_session* session, bool is_paused);

void tr_sessionSetDeleteSource(tr_session* session, bool delete_source);

tr_priority_t tr_torrentGetPriority(tr_torrent const* tor);
void tr_torrentSetPriority(tr_torrent* tor, tr_priority_t priority);

// ---

/**
 * Torrent Queueing
 *
 * There are independent queues for seeding (`tr_direction::Up`) and leeching (`tr_direction::Down`).
 *
 * If the session already has enough non-stalled seeds/leeches when
 * `tr_torrentStart()` is called, the torrent will be moved into the
 * appropriate queue and its state will be `TR_STATUS_{DOWNLOAD,SEED}_WAIT`.
 *
 * To bypass the queue and unconditionally start the torrent use
 * `tr_torrentStartNow()`.
 *
 * Torrents can be moved to arbitrary points in the queue with
 * `tr_torrentSetQueuePosition()`.
 */

/** @brief Like `tr_torrentStart()`, but resumes right away regardless of the queues. */
void tr_torrentStartNow(tr_torrent* tor);

/** @brief Set the queued torrent's position in the queue it's in.
 * Edge cases: `pos <= 0` moves to the front; `pos >= queue's length` moves to the back */
void tr_torrentSetQueuePosition(tr_torrent* tor, size_t queue_position);

// ---

/** @brief Return the number of torrents allowed to download (if direction is `tr_direction::Down`) or seed (if direction is `tr_direction::Up`) at the same time */
size_t tr_sessionGetQueueSize(tr_session const* session, tr_direction dir);

/** @brief Set the number of torrents allowed to download (if direction is `tr_direction::Down`) or seed (if direction is `tr_direction::Up`) at the same time */
void tr_sessionSetQueueSize(tr_session* session, tr_direction dir, size_t max_simultaneous_torrents);

/** @brief Return true if we're limiting how many torrents can concurrently download (`tr_direction::Down`) or seed (`tr_direction::Up`) at the same time */
bool tr_sessionGetQueueEnabled(tr_session const* session, tr_direction dir);

/** @brief Set whether or not to limit how many torrents can download (`tr_direction::Down`) or seed (`tr_direction::Up`) at the same time */
void tr_sessionSetQueueEnabled(tr_session* session, tr_direction dir, bool do_limit_simultaneous_torrents);

// ---

/** @return the number of minutes a torrent can be idle before being considered as stalled */
size_t tr_sessionGetQueueStalledMinutes(tr_session const* session);

/** @brief Consider torrent as 'stalled' when it's been inactive for N minutes.
    Stalled torrents are left running but are not counted by `tr_sessionGetQueueSize()`. */
void tr_sessionSetQueueStalledMinutes(tr_session* session, int minutes);

/** @return true if torrents idle for over N minutes will be flagged as 'stalled' */
bool tr_sessionGetQueueStalledEnabled(tr_session const* session);

/** @brief Set whether or not to count torrents idle for over N minutes as 'stalled' */
void tr_sessionSetQueueStalledEnabled(tr_session* session, bool enabled);

/** @brief Set a callback that is invoked when the queue starts a torrent */
void tr_sessionSetQueueStartCallback(tr_session* session, tr_session_queue_start_func callback);

// ---

/** @brief Set whether or not to verify data when torrent download is complete */
void tr_sessionSetCompleteVerifyEnabled(tr_session* session, bool enabled);

// ---

/**
 * Load all the torrents in the session's torrent folder.
 * This can be used at startup to kickstart all the torrents from the previous session.
 *
 * @return the number of torrents in the session
 */
size_t tr_sessionLoadTorrents(tr_session* session, tr_ctor* ctor);

/**
 * Get pointers to all the torrents in a session.
 *
 * Iff `buflen` is large enough to hold the torrents pointers,
 * then all of them are copied into `buf`.
 *
 * @return the number of torrents in the session
 */
size_t tr_sessionGetAllTorrents(tr_session* session, tr_torrent** buf, size_t buflen);

// ---

[[nodiscard]] std::string tr_sessionGetScript(tr_session const* session, TrScript type);

void tr_sessionSetScript(tr_session* session, TrScript type, std::string_view script_filename);

bool tr_sessionIsScriptEnabled(tr_session const* session, TrScript type);

void tr_sessionSetScriptEnabled(tr_session* session, TrScript type, bool enabled);

/** @} */

// ---

/** @addtogroup Blocklists
    @{ */

/**
 * Specify a range of IPs for Transmission to block.
 *
 * Filename must be an uncompressed ascii file.
 *
 * libtransmission does not keep a handle to `filename`
 * after this call returns, so the caller is free to
 * keep or delete `filename` as it wishes.
 * libtransmission makes its own copy of the file
 * massaged into a binary format easier to search.
 *
 * The caller only needs to invoke this when the blocklist
 * has changed.
 */
size_t tr_blocklistSetContent(tr_session* session, std::string_view content_filename);

size_t tr_blocklistGetRuleCount(tr_session const* session);

bool tr_blocklistExists(tr_session const* session);

bool tr_blocklistIsEnabled(tr_session const* session);

void tr_blocklistSetEnabled(tr_session* session, bool is_enabled);

[[nodiscard]] std::string tr_blocklistGetURL(tr_session const* session);

/** @brief The blocklist that gets updated when an RPC client
           invokes the "blocklist_update" method */
void tr_blocklistSetURL(tr_session* session, std::string_view url);

/** @} */

/**
 * Instantiating tr_torrents and wrangling torrent file metadata
 *
 * 1. Torrent metadata is handled in the `tr_torrent_metadata` class.
 *
 * 2. Torrents should be instantiated using a torrent builder (`tr_ctor`).
 * Calling one of the `tr_ctorSetMetainfo*()` functions is required.
 * Other settings, e.g. torrent priority, are optional.
 * When ready, pass the builder object to `tr_torrentNew()`.
 */

/** @brief Create a torrent constructor object used to instantiate a `tr_torrent`
    @param session the tr_session. */
tr_ctor* tr_ctorNew(tr_session* session);

/** @brief Free a torrent constructor object */
void tr_ctorFree(tr_ctor* ctor);

/** @brief Get the "delete torrent file" flag from this peer constructor */
bool tr_ctorGetDeleteSource(tr_ctor const* ctor, bool* setme_do_delete);

/** @brief Set whether or not to delete the source torrent file
           when the torrent is added. (Default: False) */
void tr_ctorSetDeleteSource(tr_ctor* ctor, bool delete_source);

/** @brief Set the constructor's metainfo from a magnet link */
bool tr_ctorSetMetainfoFromMagnetLink(tr_ctor* ctor, std::string_view magnet, tr_error* error = nullptr);

tr_torrent_metainfo const* tr_ctorGetMetainfo(tr_ctor const* ctor);

/** @brief Set the constructor's metainfo from a raw benc already in memory */
bool tr_ctorSetMetainfo(tr_ctor* ctor, char const* metainfo, size_t len, tr_error* error);

/** @brief Set the constructor's metainfo from a local torrent file */
bool tr_ctorSetMetainfoFromFile(tr_ctor* ctor, std::string_view filename, tr_error* error = nullptr);

/** @brief Get this peer constructor's peer limit */
bool tr_ctorGetPeerLimit(tr_ctor const* ctor, tr_ctorMode mode, uint16_t* setme_count);

/** @brief Set how many peers this torrent can connect to. (Default: 50) */
void tr_ctorSetPeerLimit(tr_ctor* ctor, tr_ctorMode mode, uint16_t limit);

/** @brief Get the download path from this peer constructor */
std::optional<std::string> tr_ctorGetDownloadDir(tr_ctor const* ctor, tr_ctorMode mode);

/** @brief Set the download folder for the torrent being added with this ctor.
    @see `tr_sessionInit()` */
void tr_ctorSetDownloadDir(tr_ctor* ctor, tr_ctorMode mode, std::string_view dir);

/**
 * @brief Set the incompleteDir for this torrent.
 *
 * This is not a supported API call.
 * It only exists so the mac client can migrate
 * its older incompleteDir settings, and that's
 * the only place where it should be used.
 */
void tr_ctorSetIncompleteDir(tr_ctor* ctor, std::string_view dir);

/** @brief Get the "isPaused" flag from this peer constructor */
bool tr_ctorGetPaused(tr_ctor const* ctor, tr_ctorMode mode, bool* setme_is_paused);

/** Set whether or not the torrent begins downloading/seeding when created.
  (Default: not paused) */
void tr_ctorSetPaused(tr_ctor* ctor, tr_ctorMode mode, bool is_paused);

/** @brief Get the torrent file that this ctor's metainfo came from,
           or empty if `tr_ctorSetMetainfoFromFile()` wasn't used */
std::optional<std::string> tr_ctorGetSourceFile(tr_ctor const* ctor);

/**
 * Instantiate a single torrent.
 *
 * Returns a pointer to the torrent on success, or nullptr on failure.
 *
 * @param ctor               the builder struct
 * @param setme_duplicate_of If the torrent couldn't be created because it's a duplicate,
 *                           this is set to point to the original torrent.
 */
tr_torrent* tr_torrentNew(tr_ctor* ctor, tr_torrent** setme_duplicate_of);

/** @} */

// --- Torrents

/** @addtogroup tr_torrent Torrents
    @{ */

/**
 * @brief Removes our torrent and .resume files for this torrent
 * @param remove_func A function that deletes a file.
 *                    The default is `tr_sys_path_remove()`
 *                    Clients can use this arg to pass in platform-specific code e.g.
 *                    to move to a recycle bin instead of deleting.
 *                    The callback is invoked in the session thread and the filename view
 *                    is only valid for the duration of the call.
 */
void tr_torrentRemove(tr_torrent* tor, bool delete_flag, tr_torrent_remove_func remove_func = {});

/** @brief Start a torrent */
void tr_torrentStart(tr_torrent* torrent);

/** @brief Stop (pause) a torrent */
void tr_torrentStop(tr_torrent* torrent);

/**
 * @brief Rename a file or directory in a torrent.
 *
 * @param tor           the torrent whose path will be renamed
 * @param oldpath       the path to the file or folder that will be renamed
 * @param newname       the file or folder's new name
 * @param callback      the callback invoked when the renaming finishes, or nullptr
 *
 * As a special case, renaming the root file in a torrent will also
 * update tr_torrentName().
 *
 * EXAMPLES
 *
 *   Consider a tr_torrent where its
 *   tr_torrentFile(tor, 0).name is "frobnitz-linux/checksum" and
 *   tr_torrentFile(tor, 1).name is "frobnitz-linux/frobnitz.iso".
 *
 *   1. tr_torrentRenamePath(tor, "frobnitz-linux", "foo") will rename
 *      the "frotbnitz-linux" folder as "foo", and update both
 *      tr_torrentName(tor) and tr_torrentFile(tor, *).name.
 *
 *   2. tr_torrentRenamePath(tor, "frobnitz-linux/checksum", "foo") will
 *      rename the "frobnitz-linux/checksum" file as "foo" and update
 *      files[0].name to "frobnitz-linux/foo".
 *
 * RETURN
 *
 *   Changing the torrent's internal fields requires a session thread lock,
 *   so this function returns asynchronously to avoid blocking. If you don't
 *   want to be notified when the function has finished, you can pass nullptr
 *   as the callback arg.
 *
 *   On success, the callback's error argument will be 0.
 *
 *   If oldpath can't be found in files[*].name, or if newname is already
 *   in files[*].name, or contains a directory separator, or is nullptr, "",
 *   ".", or "..", the error argument will be EINVAL.
 *
 *   If the path exists on disk but can't be renamed, the callback's `error`
 *   argument will be set via `set_with_errno()` with `rename()`'s errno.
 */
void tr_torrentRenamePath(
    tr_torrent* tor,
    std::string_view oldpath,
    std::string_view newname,
    tr_torrent_rename_done_func callback);

/**
 * @brief Tell transmission where to find this torrent's local data.
 *
 * if `move_from_old_path` is `true`, the torrent's incompleteDir
 * will be clobbered s.t. additional files being added will be saved
 * to the torrent's downloadDir.
 */
void tr_torrentSetLocation(tr_torrent* torrent, char const* location, bool move_from_old_path, int volatile* setme_state);

uint64_t tr_torrentGetBytesLeftToAllocate(tr_torrent const* torrent);

/**
 * @brief Returns this torrent's unique ID.
 *
 * IDs are fast lookup keys, but are not persistent between sessions.
 * If you need that, use `tr_torrentView().hash_string`.
 */
tr_torrent_id_t tr_torrentId(tr_torrent const* torrent);

tr_torrent* tr_torrentFindFromId(tr_session* session, tr_torrent_id_t id);

tr_torrent* tr_torrentFindFromMetainfo(tr_session* session, tr_torrent_metainfo const* metainfo);

[[nodiscard]] tr_torrent* tr_torrentFindFromMagnetLink(tr_session* session, std::string_view magnet_link);

/**
 * @brief Set metainfo if possible.
 * @return True if given metainfo was set.
 *
 */
bool tr_torrentSetMetainfoFromFile(tr_torrent* torrent, tr_torrent_metainfo const* metainfo, char const* filename);

/**
 * @return this torrent's name.
 */
[[nodiscard]] std::string tr_torrentName(tr_torrent const* tor);

/**
 * @brief find the location of a torrent's file by looking with and without
 *        the ".part" suffix, looking in downloadDir and incompleteDir, etc.
 * @return the path of this file, or an empty string if no file exists yet.
 * @param tor the torrent whose file we're looking for
 * @param file_num the fileIndex, in [0...tr_torrentFileCount())
 */
[[nodiscard]] std::string tr_torrentFindFile(tr_torrent const* tor, tr_file_index_t file_num);

// --- Torrent speed limits

size_t tr_torrentGetSpeedLimit_KBps(tr_torrent const* tor, tr_direction dir);
void tr_torrentSetSpeedLimit_KBps(tr_torrent* tor, tr_direction dir, size_t limit_kbyps);

bool tr_torrentUsesSpeedLimit(tr_torrent const* tor, tr_direction dir);
void tr_torrentUseSpeedLimit(tr_torrent* tor, tr_direction dir, bool enabled);

bool tr_torrentUsesSessionLimits(tr_torrent const* tor);
void tr_torrentUseSessionLimits(tr_torrent* tor, bool enabled);

// --- Ratio Limits

tr_ratiolimit tr_torrentGetRatioMode(tr_torrent const* tor);
void tr_torrentSetRatioMode(tr_torrent* tor, tr_ratiolimit mode);

double tr_torrentGetRatioLimit(tr_torrent const* tor);
void tr_torrentSetRatioLimit(tr_torrent* tor, double desired_ratio);

bool tr_torrentGetSeedRatio(tr_torrent const* tor, double* ratio);

// --- Idle Time Limits

tr_idlelimit tr_torrentGetIdleMode(tr_torrent const* tor);
void tr_torrentSetIdleMode(tr_torrent* tor, tr_idlelimit mode);

uint16_t tr_torrentGetIdleLimit(tr_torrent const* tor);
void tr_torrentSetIdleLimit(tr_torrent* tor, uint16_t idle_minutes);

// --- Peer Limits

uint16_t tr_torrentGetPeerLimit(tr_torrent const* tor);
void tr_torrentSetPeerLimit(tr_torrent* tor, uint16_t max_connected_peers);

// --- File Priorities

/**
 * @brief Set a batch of files to a particular priority.
 *
 * @param priority must be one of TR_PRI_NORMAL, _HIGH, or _LOW
 */
void tr_torrentSetFilePriorities(
    tr_torrent* torrent,
    tr_file_index_t const* files,
    tr_file_index_t file_count,
    tr_priority_t priority);

/** @brief Set a batch of files to be downloaded or not. */
void tr_torrentSetFileDLs(tr_torrent* torrent, tr_file_index_t const* files, tr_file_index_t n_files, bool wanted);

/**
 * Returns a permanently interned string of the torrent's download directory.
 */
[[nodiscard]] std::string_view tr_torrentGetDownloadDir(tr_torrent const* torrent);

/* Raw function to change the torrent's downloadDir field.
   This should only be used by libtransmission or to bootstrap
   a newly-instantiated tr_torrent object. */
void tr_torrentSetDownloadDir(tr_torrent* torrent, std::string_view path);

/**
 * Returns a permanently interned string of the torrent's root directory.
 *
 * This will usually be the downloadDir. However if the torrent
 * has an incompleteDir enabled and hasn't finished downloading
 * yet, that will be returned instead.
 */
[[nodiscard]] std::string_view tr_torrentGetCurrentDir(tr_torrent const* tor);

/**
 * Returns a the magnet link to the torrent.
 */
[[nodiscard]] std::string tr_torrentGetMagnetLink(tr_torrent const* tor);

// ---

/**
 * Returns a string listing its tracker's announce URLs.
 * One URL per line, with a blank line between tiers.
 *
 * NOTE: this only includes the trackers included in the torrent and,
 * along with `tr_torrentSetTrackerList()`, is intended for import/export
 * and user editing. It does *not* include the "default trackers" that
 * are applied to all public torrents. If you want a full display of all
 * trackers, use `tr_torrentTracker()` and `tr_torrentTrackerCount()`
 */
[[nodiscard]] std::string tr_torrentGetTrackerList(tr_torrent const* tor);

/**
 * Sets a torrent's tracker list from a list of announce URLs with one
 * URL per line and a blank line between tiers.
 *
 * This updates both the `torrent` object's tracker list
 * and the metainfo file in `tr_sessionGetConfigDir()`'s torrent subdirectory.
 */
bool tr_torrentSetTrackerList(tr_torrent* tor, std::string_view txt);

// ---

/**
 * Register to be notified whenever a torrent's "completeness"
 * changes. This will be called, for example, when a torrent
 * finishes downloading and changes from `TR_LEECH` to
 * either `TR_SEED` or `TR_PARTIAL_SEED`.
 *
 * callback is invoked FROM LIBTRANSMISSION'S THREAD!
 * This means callback must be fast (to avoid blocking peers),
 * shouldn't call libtransmission functions (to avoid deadlock),
 * and shouldn't modify client-level memory without using a mutex!
 *
 * @see `tr_completeness`
 */
void tr_sessionSetCompletenessCallback(tr_session* session, tr_torrent_completeness_func callback);

/**
 * Register to be notified whenever a torrent changes from
 * having incomplete metadata to having complete metadata.
 * This happens when a magnet link finishes downloading
 * metadata from its peers.
 */
void tr_sessionSetMetadataCallback(tr_session* session, tr_session_metadata_func callback);

/**
 * Register to be notified whenever a torrent's ratio limit
 * has been hit. This will be called when the torrent's
 * ul/dl ratio has met or exceeded the designated ratio limit.
 *
 * Has the same restrictions as `tr_sessionSetCompletenessCallback`
 */
void tr_sessionSetRatioLimitHitCallback(tr_session* session, tr_session_ratio_limit_hit_func callback);

/**
 * Register to be notified whenever a torrent's idle limit
 * has been hit. This will be called when the seeding torrent's
 * idle time has met or exceeded the designated idle limit.
 *
 * Has the same restrictions as `tr_sessionSetCompletenessCallback`
 */
void tr_sessionSetIdleLimitHitCallback(tr_session* session, tr_session_idle_limit_hit_func callback);

/**
 * MANUAL ANNOUNCE
 *
 * Trackers usually set an announce interval of 15 or 30 minutes.
 * Users can send one-time announce requests that override this
 * interval by calling `tr_torrentManualUpdate()`.
 *
 * The wait interval for `tr_torrentManualUpdate()` is much smaller.
 * You can test whether or not a manual update is possible
 * (for example, to desensitize the button) by calling
 * `tr_torrentCanManualUpdate()`.
 */

void tr_torrentManualUpdate(tr_torrent* torrent);

bool tr_torrentCanManualUpdate(tr_torrent const* torrent);

std::vector<tr_peer_stat> tr_torrentPeers(tr_torrent const* torrent);

// --- tr_tracker_stat

struct tr_tracker_view tr_torrentTracker(tr_torrent const* torrent, size_t i);

/**
 * Count all the trackers (both active and backup) this torrent is using.
 *
 * NOTE: this is for a status display only and may include trackers from
 * the default tracker list if this is a public torrent. If you want a
 * list of trackers the  user can edit, see `tr_torrentGetTrackerList()`.
 */
size_t tr_torrentTrackerCount(tr_torrent const* torrent);

tr_file_view tr_torrentFile(tr_torrent const* torrent, tr_file_index_t file);

size_t tr_torrentFileCount(tr_torrent const* torrent);

struct tr_webseed_view tr_torrentWebseed(tr_torrent const* torrent, size_t nth);

size_t tr_torrentWebseedCount(tr_torrent const* torrent);

struct tr_torrent_view tr_torrentView(tr_torrent const* tor);

/*
 * Get the filename of Transmission's internal copy of the torrent file.
 */
[[nodiscard]] std::string tr_torrentFilename(tr_torrent const* tor);

/**
 * Use this to draw an advanced progress bar which is 'size' pixels
 * wide. Fills 'tab' which you must have allocated: each byte is set
 * to either -1 if we have the piece, otherwise it is set to the number
 * of connected peers who have the piece.
 */
void tr_torrentAvailability(tr_torrent const* torrent, int8_t* tab, int size);

void tr_torrentAmountFinished(tr_torrent const* torrent, float* tab, int n_tabs);

/**
 * Queue a torrent for verification.
 */
void tr_torrentVerify(tr_torrent* torrent);

bool tr_torrentHasMetadata(tr_torrent const* tor);

// Return a `tr_stat` structure with updated information on the torrent.
// This is typically called by the GUI clients every
// second or so to get a new snapshot of the torrent's status.
tr_stat tr_torrentStat(tr_torrent* torrent);

// Batch version of tr_torrentStat().
// Prefer calling this over calling the single-torrent version in a loop.
// TODO(c++20) take a std::span argument
std::vector<tr_stat> tr_torrentStat(tr_torrent* const* torrents, size_t n_torrents);