mpd/src/playlist.c

/* the Music Player Daemon (MPD)
 * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com)
 * This project's homepage is: http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "playlist.h"
#include "playlist_save.h"
#include "queue_print.h"
#include "queue_save.h"
#include "locate.h"
#include "player_control.h"
#include "command.h"
#include "ls.h"
#include "tag.h"
#include "song.h"
#include "conf.h"
#include "database.h"
#include "mapper.h"
#include "path.h"
#include "stored_playlist.h"
#include "ack.h"
#include "idle.h"
#include "event_pipe.h"

#include <glib.h>

#include <assert.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>

/**
 * When the "prev" command is received, rewind the current track if
 * this number of seconds has already elapsed.
 */
#define PLAYLIST_PREV_UNLESS_ELAPSED    10

#define PLAYLIST_STATE_FILE_STATE		"state: "
#define PLAYLIST_STATE_FILE_RANDOM		"random: "
#define PLAYLIST_STATE_FILE_REPEAT		"repeat: "
#define PLAYLIST_STATE_FILE_CURRENT		"current: "
#define PLAYLIST_STATE_FILE_TIME		"time: "
#define PLAYLIST_STATE_FILE_CROSSFADE		"crossfade: "
#define PLAYLIST_STATE_FILE_PLAYLIST_BEGIN	"playlist_begin"
#define PLAYLIST_STATE_FILE_PLAYLIST_END	"playlist_end"

#define PLAYLIST_STATE_FILE_STATE_PLAY		"play"
#define PLAYLIST_STATE_FILE_STATE_PAUSE		"pause"
#define PLAYLIST_STATE_FILE_STATE_STOP		"stop"

#define PLAYLIST_BUFFER_SIZE	2*MPD_PATH_MAX

#define PLAYLIST_HASH_MULT	4

#define DEFAULT_PLAYLIST_MAX_LENGTH		(1024*16)
#define DEFAULT_PLAYLIST_SAVE_ABSOLUTE_PATHS	false

/** random number generator fur shuffling */
static GRand *g_rand;

/** the global playlist object */
static struct playlist playlist;
unsigned playlist_max_length;

bool playlist_saveAbsolutePaths = DEFAULT_PLAYLIST_SAVE_ABSOLUTE_PATHS;

static void playPlaylistOrderNumber(int orderNum);

static void incrPlaylistVersion(void)
{
	queue_increment_version(&playlist.queue);

	idle_add(IDLE_PLAYLIST);
}

void playlistVersionChange(void)
{
	queue_modify_all(&playlist.queue);
	idle_add(IDLE_PLAYLIST);
}

static void
playlist_tag_event(void)
{
	if (!playlist.playing)
		return;

	assert(playlist.current >= 0);

	queue_modify(&playlist.queue, playlist.current);
	idle_add(IDLE_PLAYLIST);
}

void initPlaylist(void)
{
	g_rand = g_rand_new();

	playlist_max_length = config_get_positive(CONF_MAX_PLAYLIST_LENGTH,
						  DEFAULT_PLAYLIST_MAX_LENGTH);

	queue_init(&playlist.queue, playlist_max_length);

	playlist.queued = -1;
	playlist.current = -1;

	playlist_saveAbsolutePaths =
		config_get_bool(CONF_SAVE_ABSOLUTE_PATHS,
				DEFAULT_PLAYLIST_SAVE_ABSOLUTE_PATHS);

	event_pipe_register(PIPE_EVENT_TAG, playlist_tag_event);
}

void finishPlaylist(void)
{
	queue_finish(&playlist.queue);

	g_rand_free(g_rand);
	g_rand = NULL;
}

const struct queue *
playlist_get_queue(void)
{
	return &playlist.queue;
}

void clearPlaylist(void)
{
	stopPlaylist();

	/* make sure there are no references to allocated songs
	   anymore */
	for (unsigned i = 0; i < queue_length(&playlist.queue); i++) {
		const struct song *song = queue_get(&playlist.queue, i);
		if (!song_in_database(song))
			pc_song_deleted(song);
	}

	queue_clear(&playlist.queue);

	playlist.current = -1;

	incrPlaylistVersion();
}

void savePlaylistState(FILE *fp)
{
	fprintf(fp, "%s", PLAYLIST_STATE_FILE_STATE);

	if (playlist.playing) {
		switch (getPlayerState()) {
		case PLAYER_STATE_PAUSE:
			fprintf(fp, "%s\n", PLAYLIST_STATE_FILE_STATE_PAUSE);
			break;
		default:
			fprintf(fp, "%s\n", PLAYLIST_STATE_FILE_STATE_PLAY);
		}
		fprintf(fp, "%s%i\n", PLAYLIST_STATE_FILE_CURRENT,
			queue_order_to_position(&playlist.queue,
						playlist.current));
		fprintf(fp, "%s%i\n", PLAYLIST_STATE_FILE_TIME,
		        getPlayerElapsedTime());
	} else
		fprintf(fp, "%s\n", PLAYLIST_STATE_FILE_STATE_STOP);

	fprintf(fp, "%s%i\n", PLAYLIST_STATE_FILE_RANDOM,
		playlist.queue.random);
	fprintf(fp, "%s%i\n", PLAYLIST_STATE_FILE_REPEAT,
		playlist.queue.repeat);
	fprintf(fp, "%s%i\n", PLAYLIST_STATE_FILE_CROSSFADE,
	        (int)(getPlayerCrossFade()));
	fprintf(fp, "%s\n", PLAYLIST_STATE_FILE_PLAYLIST_BEGIN);
	queue_save(fp, &playlist.queue);
	fprintf(fp, "%s\n", PLAYLIST_STATE_FILE_PLAYLIST_END);
}

static void loadPlaylistFromStateFile(FILE *fp, char *buffer,
				      int state, int current, int seek_time)
{
	int song;

	if (!fgets(buffer, PLAYLIST_BUFFER_SIZE, fp)) {
		g_warning("No playlist in state file");
		return;
	}

	while (!g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_PLAYLIST_END)) {
		g_strchomp(buffer);

		song = queue_load_song(&playlist.queue, buffer);
		if (song >= 0 && song == current) {
			if (state != PLAYER_STATE_STOP) {
				playPlaylist(queue_length(&playlist.queue) - 1);
			}
			if (state == PLAYER_STATE_PAUSE) {
				playerPause();
			}
			if (state != PLAYER_STATE_STOP) {
				seekSongInPlaylist(queue_length(&playlist.queue) - 1,
						   seek_time);
			}
		}

		if (!fgets(buffer, PLAYLIST_BUFFER_SIZE, fp)) {
			g_warning("'%s' not found in state file",
				  PLAYLIST_STATE_FILE_PLAYLIST_END);
			break;
		}
	}
}

void readPlaylistState(FILE *fp)
{
	int current = -1;
	int seek_time = 0;
	int state = PLAYER_STATE_STOP;
	char buffer[PLAYLIST_BUFFER_SIZE];
	bool random_mode = false;

	while (fgets(buffer, sizeof(buffer), fp)) {
		g_strchomp(buffer);

		if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_STATE)) {
			if (strcmp(&(buffer[strlen(PLAYLIST_STATE_FILE_STATE)]),
				   PLAYLIST_STATE_FILE_STATE_PLAY) == 0) {
				state = PLAYER_STATE_PLAY;
			} else
			    if (strcmp
				(&(buffer[strlen(PLAYLIST_STATE_FILE_STATE)]),
				 PLAYLIST_STATE_FILE_STATE_PAUSE)
				== 0) {
				state = PLAYER_STATE_PAUSE;
			}
		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_TIME)) {
			seek_time =
			    atoi(&(buffer[strlen(PLAYLIST_STATE_FILE_TIME)]));
		} else
		    if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_REPEAT)) {
			if (strcmp
			    (&(buffer[strlen(PLAYLIST_STATE_FILE_REPEAT)]),
			     "1") == 0) {
				setPlaylistRepeatStatus(true);
			} else
				setPlaylistRepeatStatus(false);
		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_CROSSFADE)) {
			setPlayerCrossFade(atoi
					   (&
					    (buffer
					     [strlen
					      (PLAYLIST_STATE_FILE_CROSSFADE)])));
		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_RANDOM)) {
			random_mode =
				strcmp(buffer + strlen(PLAYLIST_STATE_FILE_RANDOM),
				       "1") == 0;
		} else if (g_str_has_prefix(buffer, PLAYLIST_STATE_FILE_CURRENT)) {
			current = atoi(&(buffer
					 [strlen
					  (PLAYLIST_STATE_FILE_CURRENT)]));
		} else if (g_str_has_prefix(buffer,
					    PLAYLIST_STATE_FILE_PLAYLIST_BEGIN)) {
			if (state == PLAYER_STATE_STOP)
				current = -1;
			loadPlaylistFromStateFile(fp, buffer, state,
						  current, seek_time);
		}
	}

	setPlaylistRandomStatus(random_mode);
}

/**
 * Queue a song, addressed by its order number.
 */
static void
playlist_queue_song_order(unsigned order)
{
	struct song *song;
	char *uri;

	assert(queue_valid_order(&playlist.queue, order));

	playlist.queued = order;

	song = queue_get_order(&playlist.queue, order);
	uri = song_get_uri(song);
	g_debug("playlist: queue song %i:\"%s\"",
		playlist.queued, uri);
	g_free(uri);

	queueSong(song);
}

/*
 * Queue the song following after the current one.  If no song is
 * played currently, start with the first song.
 */
static void queueNextSongInPlaylist(void)
{
	assert(playlist.queued < 0);

	if (playlist.current + 1 < (int)queue_length(&playlist.queue)) {
		playlist_queue_song_order(playlist.current + 1);
	} else if (!queue_is_empty(&playlist.queue) && playlist.queue.repeat) {
		/* end of queue: restart at the first song in repeat
		   mode */

		if (playlist.queue.random) {
			/* shuffle the song order again, so we get a
			   different order each time the playlist is
			   played completely */

			unsigned current_position =
				queue_order_to_position(&playlist.queue,
							playlist.current);
			queue_shuffle_order(&playlist.queue);

			/* make sure that the playlist.current still
			   points to the current song, after the song
			   order has been shuffled */
			playlist.current =
				queue_position_to_order(&playlist.queue,
							current_position);
		}

		playlist_queue_song_order(0);
	}
}

/**
 * Check if the player thread has already started playing the "queued"
 * song.
 */
static void syncPlaylistWithQueue(void)
{
	if (pc.next_song == NULL && playlist.queued != -1) {
		/* queued song has started: copy queued to current,
		   and notify the clients */

		playlist.current = playlist.queued;
		playlist.queued = -1;

		idle_add(IDLE_PLAYER);
	}
}

/**
 * Clears the currently queued song, and tells the player thread to
 * abort pre-decoding it.
 */
static void clearPlayerQueue(void)
{
	assert(playlist.queued >= 0);

	playlist.queued = -1;

	pc_cancel();
}

#ifndef WIN32
enum playlist_result
playlist_append_file(const char *path, int uid, unsigned *added_id)
{
	int ret;
	struct stat st;
	struct song *song;

	if (uid <= 0)
		/* unauthenticated client */
		return PLAYLIST_RESULT_DENIED;

	ret = stat(path, &st);
	if (ret < 0)
		return PLAYLIST_RESULT_ERRNO;

	if (st.st_uid != (uid_t)uid && (st.st_mode & 0444) != 0444)
		/* client is not owner */
		return PLAYLIST_RESULT_DENIED;

	song = song_file_load(path, NULL);
	if (song == NULL)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return addSongToPlaylist(song, added_id);
}
#endif

static struct song *
song_by_url(const char *url)
{
	struct song *song;

	song = db_get_song(url);
	if (song != NULL)
		return song;

	if (uri_has_scheme(url))
		return song_remote_new(url);

	return NULL;
}

enum playlist_result addToPlaylist(const char *url, unsigned *added_id)
{
	struct song *song;

	g_debug("add to playlist: %s", url);

	song = song_by_url(url);
	if (song == NULL)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return addSongToPlaylist(song, added_id);
}

enum playlist_result
addSongToPlaylist(struct song *song, unsigned *added_id)
{
	unsigned id;

	if (queue_is_full(&playlist.queue))
		return PLAYLIST_RESULT_TOO_LARGE;

	if (playlist.playing && playlist.queued >= 0 &&
	    playlist.current == (int)queue_length(&playlist.queue) - 1)
		/* currently, we are playing the last song in the
		   queue - the new song will be the new "queued song",
		   so we have to clear the old queued song first */
		clearPlayerQueue();

	id = queue_append(&playlist.queue, song);

	if (playlist.queue.random) {
		/* shuffle the new song into the list of remaining
		   songs to play */

		unsigned start;
		if (playlist.queued >= 0)
			start = playlist.queued + 1;
		else
			start = playlist.current + 1;
		if (start < queue_length(&playlist.queue)) {
			unsigned swap = g_rand_int_range(g_rand, start,
							 queue_length(&playlist.queue));
			queue_swap_order(&playlist.queue,
					 queue_length(&playlist.queue) - 1, swap);
		}
	}

	incrPlaylistVersion();

	if (added_id)
		*added_id = id;

	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result swapSongsInPlaylist(unsigned song1, unsigned song2)
{
	if (!queue_valid_position(&playlist.queue, song1) ||
	    !queue_valid_position(&playlist.queue, song2))
		return PLAYLIST_RESULT_BAD_RANGE;

	if (playlist.playing && playlist.queued >= 0) {
		/* if song1 or song2 equals to the current or the
		   queued song, we must clear the player queue,
		   because the swap will result in a different
		   "queued" song */

		unsigned queuedSong = queue_order_to_position(&playlist.queue,
							      playlist.queued);
		unsigned currentSong = queue_order_to_position(&playlist.queue,
							       playlist.current);

		if (queuedSong == song1 || queuedSong == song2
		    || currentSong == song1 || currentSong == song2)
			clearPlayerQueue();
	}

	queue_swap(&playlist.queue, song1, song2);

	if (playlist.queue.random) {
		/* update the queue order, so that playlist.current
		   still points to the current song order */

		queue_swap_order(&playlist.queue,
				 queue_position_to_order(&playlist.queue,
							 song1),
				 queue_position_to_order(&playlist.queue,
							 song2));
	} else {
		/* correct the "current" song order */

		if (playlist.current == (int)song1)
			playlist.current = song2;
		else if (playlist.current == (int)song2)
			playlist.current = song1;
	}

	incrPlaylistVersion();

	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result swapSongsInPlaylistById(unsigned id1, unsigned id2)
{
	int song1 = queue_id_to_position(&playlist.queue, id1);
	int song2 = queue_id_to_position(&playlist.queue, id2);

	if (song1 < 0 || song2 < 0)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return swapSongsInPlaylist(song1, song2);
}

enum playlist_result deleteFromPlaylist(unsigned song)
{
	unsigned songOrder;

	if (song >= queue_length(&playlist.queue))
		return PLAYLIST_RESULT_BAD_RANGE;

	songOrder = queue_position_to_order(&playlist.queue, song);

	if (playlist.playing && playlist.queued >= 0
	    && (playlist.queued == (int)songOrder ||
		playlist.current == (int)songOrder))
		/* deleting the current or the queued song: clear the
		   queue, because this function will result in a
		   different "queued" song */
		clearPlayerQueue();

	if (playlist.playing && playlist.current == (int)songOrder) {
		bool paused = getPlayerState() == PLAYER_STATE_PAUSE;

		/* the current song is going to be deleted: stop the player */

		playerWait();

		/* see which song is going to be played instead */

		playlist.current = queue_next_order(&playlist.queue,
						    playlist.current);
		if (playlist.current == (int)songOrder)
			playlist.current = -1;

		if (playlist.current >= 0 && !paused)
			/* play the song after the deleted one */
			playPlaylistOrderNumber(playlist.current);
		else
			/* no songs left to play, stop playback
			   completely */
			stopPlaylist();
	}

	/* now do it: remove the song */

	if (!song_in_database(queue_get(&playlist.queue, song)))
		pc_song_deleted(queue_get(&playlist.queue, song));

	queue_delete(&playlist.queue, song);

	incrPlaylistVersion();

	/* update the "current" and "queued" variables */

	if (playlist.current > (int)songOrder) {
		playlist.current--;
	}

	if (playlist.queued > (int)songOrder) {
		playlist.queued--;
	}

	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result deleteFromPlaylistById(unsigned id)
{
	int song = queue_id_to_position(&playlist.queue, id);
	if (song < 0)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return deleteFromPlaylist(song);
}

void
deleteASongFromPlaylist(const struct song *song)
{
	for (int i = queue_length(&playlist.queue) - 1; i >= 0; --i)
		if (song == queue_get(&playlist.queue, i))
			deleteFromPlaylist(i);

	pc_song_deleted(song);
}

void stopPlaylist(void)
{
	if (!playlist.playing)
		return;

	assert(playlist.current >= 0);

	g_debug("playlist: stop");
	playerWait();
	playlist.queued = -1;
	playlist.playing = false;

	if (playlist.queue.random) {
		/* shuffle the playlist, so the next playback will
		   result in a new random order */

		unsigned current_position =
			queue_order_to_position(&playlist.queue,
						playlist.current);

		queue_shuffle_order(&playlist.queue);

		/* make sure that "current" stays valid, and the next
		   "play" command plays the same song again */
		playlist.current =
			queue_position_to_order(&playlist.queue,
						current_position);
	}
}

static void playPlaylistOrderNumber(int orderNum)
{
	struct song *song;
	char *uri;

	playlist.playing = true;
	playlist.queued = -1;

	song = queue_get_order(&playlist.queue, orderNum);

	uri = song_get_uri(song);
	g_debug("playlist: play %i:\"%s\"", orderNum, uri);
	g_free(uri);

	playerPlay(song);
	playlist.current = orderNum;
}

enum playlist_result playPlaylist(int song)
{
	unsigned i = song;

	clearPlayerError();

	if (song == -1) {
		/* play any song ("current" song, or the first song */

		if (queue_is_empty(&playlist.queue))
			return PLAYLIST_RESULT_SUCCESS;

		if (playlist.playing) {
			/* already playing: unpause playback, just in
			   case it was paused, and return */
			playerSetPause(0);
			return PLAYLIST_RESULT_SUCCESS;
		}

		/* select a song: "current" song, or the first one */
		i = playlist.current >= 0
			? playlist.current
			: 0;
	} else if (!queue_valid_position(&playlist.queue, song))
		return PLAYLIST_RESULT_BAD_RANGE;

	if (playlist.queue.random) {
		if (song >= 0)
			/* "i" is currently the song position (which
			   would be equal to the order number in
			   no-random mode); convert it to a order
			   number, because random mode is enabled */
			i = queue_position_to_order(&playlist.queue, song);

		if (!playlist.playing)
			playlist.current = 0;

		/* swap the new song with the previous "current" one,
		   so playback continues as planned */
		queue_swap_order(&playlist.queue,
				 i, playlist.current);
		i = playlist.current;
	}

	playlist.stop_on_error = false;
	playlist.error_count = 0;

	playPlaylistOrderNumber(i);
	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result playPlaylistById(int id)
{
	int song;

	if (id == -1) {
		return playPlaylist(id);
	}

	song = queue_id_to_position(&playlist.queue, id);
	if (song < 0)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return playPlaylist(song);
}

static void playPlaylistIfPlayerStopped(void);

/**
 * This is the "PLAYLIST" event handler.  It is invoked by the player
 * thread whenever it requests a new queued song, or when it exits.
 */
void syncPlayerAndPlaylist(void)
{
	if (!playlist.playing)
		/* this event has reached us out of sync: we aren't
		   playing anymore; ignore the event */
		return;

	if (getPlayerState() == PLAYER_STATE_STOP)
		/* the player thread has stopped: check if playback
		   should be restarted with the next song.  That can
		   happen if the playlist isn't filling the queue fast
		   enough */
		playPlaylistIfPlayerStopped();
	else {
		/* check if the player thread has already started
		   playing the queued song */
		syncPlaylistWithQueue();

		/* make sure the queued song is always set (if
		   possible) */
		if (pc.next_song == NULL)
			queueNextSongInPlaylist();
	}
}

void nextSongInPlaylist(void)
{
	int next_order;

	if (!playlist.playing)
		return;

	assert(!queue_is_empty(&playlist.queue));
	assert(queue_valid_order(&playlist.queue, playlist.current));

	syncPlaylistWithQueue();

	playlist.stop_on_error = false;

	/* determine the next song from the queue's order list */

	next_order = queue_next_order(&playlist.queue, playlist.current);
	if (next_order < 0) {
		/* no song after this one: stop playback */
		stopPlaylist();
		return;
	}

	if (next_order == 0 && playlist.queue.random) {
		/* The queue told us that the next song is the first
		   song.  This means we are in repeat mode.  Shuffle
		   the queue order, so this time, the user hears the
		   songs in a different than before */
		assert(playlist.queue.repeat);

		queue_shuffle_order(&playlist.queue);

		/* note that playlist.current and playlist.queued are
		   now invalid, but playPlaylistOrderNumber() will
		   discard them anyway */
	}

	playPlaylistOrderNumber(next_order);
}

/**
 * The player has stopped for some reason.  Check the error, and
 * decide whether to re-start playback
 */
static void playPlaylistIfPlayerStopped(void)
{
	enum player_error error;

	assert(playlist.playing);
	assert(getPlayerState() == PLAYER_STATE_STOP);

	error = getPlayerError();
	if (error == PLAYER_ERROR_NOERROR)
		playlist.error_count = 0;
	else
		++playlist.error_count;

	if ((playlist.stop_on_error && error != PLAYER_ERROR_NOERROR) ||
	    error == PLAYER_ERROR_AUDIO || error == PLAYER_ERROR_SYSTEM ||
	    playlist.error_count >= queue_length(&playlist.queue))
		/* too many errors, or critical error: stop
		   playback */
		stopPlaylist();
	else
		/* continue playback at the next song */
		nextSongInPlaylist();
}

bool getPlaylistRepeatStatus(void)
{
	return playlist.queue.repeat;
}

bool getPlaylistRandomStatus(void)
{
	return playlist.queue.random;
}

void setPlaylistRepeatStatus(bool status)
{
	if (status == playlist.queue.repeat)
		return;

	if (playlist.playing &&
	    playlist.queue.repeat && playlist.queued == 0)
		/* repeat mode will be switched off now - tell the
		   player thread not to play the first song again */
		clearPlayerQueue();

	playlist.queue.repeat = status;

	idle_add(IDLE_OPTIONS);
}

enum playlist_result moveSongInPlaylist(unsigned from, int to)
{
	int currentSong;

	if (!queue_valid_position(&playlist.queue, from))
		return PLAYLIST_RESULT_BAD_RANGE;

	if ((to >= 0 && to >= (int)queue_length(&playlist.queue)) ||
	    (to < 0 && abs(to) > (int)queue_length(&playlist.queue)))
		return PLAYLIST_RESULT_BAD_RANGE;

	if ((int)from == to) /* no-op */
		return PLAYLIST_RESULT_SUCCESS;

	/*
	 * (to < 0) => move to offset from current song
	 * (-playlist.length == to) => move to position BEFORE current song
	 */
	currentSong = playlist.current >= 0
		? (int)queue_order_to_position(&playlist.queue,
					      playlist.current)
		: -1;
	if (to < 0 && playlist.current >= 0) {
		if ((unsigned)currentSong == from)
			/* no-op, can't be moved to offset of itself */
			return PLAYLIST_RESULT_SUCCESS;
		to = (currentSong + abs(to)) % queue_length(&playlist.queue);
	}

	if (playlist.playing && playlist.queued >= 0) {
		int queuedSong = queue_order_to_position(&playlist.queue,
							 playlist.queued);
		if (queuedSong == (int)from || queuedSong == to
		    || currentSong == (int)from || currentSong == to)
			clearPlayerQueue();
	}

	queue_move(&playlist.queue, from, to);

	if (!playlist.queue.random) {
		/* update current/queued */
		if (playlist.current == (int)from)
			playlist.current = to;
		else if (playlist.current > (int)from &&
			 playlist.current <= to) {
			playlist.current--;
		} else if (playlist.current >= to &&
			   playlist.current < (int)from) {
			playlist.current++;
		}

		/* this first if statement isn't necessary since the queue
		 * would have been cleared out if queued == from */
		if (playlist.queued == (int)from)
			playlist.queued = to;
		else if (playlist.queued > (int)from && playlist.queued <= to) {
			playlist.queued--;
		} else if (playlist.queued>= to && playlist.queued < (int)from) {
			playlist.queued++;
		}
	}

	incrPlaylistVersion();

	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result moveSongInPlaylistById(unsigned id1, int to)
{
	int song = queue_id_to_position(&playlist.queue, id1);
	if (song < 0)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return moveSongInPlaylist(song, to);
}

static void orderPlaylist(void)
{
	if (playlist.current >= 0)
		/* update playlist.current, order==position now */
		playlist.current = queue_order_to_position(&playlist.queue,
							   playlist.current);

	if (playlist.playing && playlist.queued >= 0)
		/* clear the queue, because the next song will be
		   different now */
		clearPlayerQueue();

	queue_restore_order(&playlist.queue);
}

void setPlaylistRandomStatus(bool status)
{
	if (status == playlist.queue.random)
		return;

	if (playlist.queued >= 0)
		clearPlayerQueue();

	playlist.queue.random = status;

	if (playlist.queue.random) {
		/* shuffle the queue order, but preserve
		   playlist.current */

		int current_position = playlist.current >= 0
			? (int)queue_order_to_position(&playlist.queue,
						       playlist.current)
			: -1;

		queue_shuffle_order(&playlist.queue);

		if (current_position >= 0) {
			/* make sure the current song is the first in
			   the order list, so the whole rest of the
			   playlist is played after that */
			unsigned current_order =
				queue_position_to_order(&playlist.queue,
							current_position);
			queue_swap_order(&playlist.queue, 0, current_order);
			playlist.current = 0;
		}
	} else
		orderPlaylist();

	idle_add(IDLE_OPTIONS);
}

void previousSongInPlaylist(void)
{
	static time_t lastTime;
	time_t diff = time(NULL) - lastTime;

	lastTime += diff;

	if (!playlist.playing)
		return;

	syncPlaylistWithQueue();

	if (diff && getPlayerElapsedTime() > PLAYLIST_PREV_UNLESS_ELAPSED) {
		/* re-start playing the current song (just like the
		   "prev" button on CD players) */

		playPlaylistOrderNumber(playlist.current);
	} else {
		if (playlist.current > 0) {
			/* play the preceding song */
			playPlaylistOrderNumber(playlist.current - 1);
		} else if (playlist.queue.repeat) {
			/* play the last song in "repeat" mode */
			playPlaylistOrderNumber(queue_length(&playlist.queue) - 1);
		} else {
			/* re-start playing the current song if it's
			   the first one */
			playPlaylistOrderNumber(playlist.current);
		}
	}
}

void shufflePlaylist(void)
{
	unsigned i;

	if (queue_length(&playlist.queue) <= 1)
		return;

	if (playlist.playing) {
		if (playlist.queued >= 0)
			/* queue must be cleared, because the "next"
			   song will be different after shuffle */
			clearPlayerQueue();

		if (playlist.current >= 0)
			/* put current playing song first */
			queue_swap(&playlist.queue, 0,
				   queue_order_to_position(&playlist.queue,
							   playlist.current));

		if (playlist.queue.random) {
			playlist.current =
				queue_position_to_order(&playlist.queue, 0);
		} else
			playlist.current = 0;

		/* start shuffle after the current song */
		i = 1;
	} else {
		/* no playback currently: shuffle everything, and
		   reset playlist.current */

		i = 0;
		playlist.current = -1;
	}

	/* shuffle the rest of the list */
	queue_shuffle_range(&playlist.queue, i,
			    queue_length(&playlist.queue));

	incrPlaylistVersion();
}

enum playlist_result savePlaylist(const char *utf8file)
{
	FILE *fp;
	char *path;

	if (!is_valid_playlist_name(utf8file))
		return PLAYLIST_RESULT_BAD_NAME;

	path = map_spl_utf8_to_fs(utf8file);
	if (path == NULL)
		return PLAYLIST_RESULT_DISABLED;

	if (g_file_test(path, G_FILE_TEST_EXISTS)) {
		g_free(path);
		return PLAYLIST_RESULT_LIST_EXISTS;
	}

	while (!(fp = fopen(path, "w")) && errno == EINTR);
	g_free(path);

	if (fp == NULL)
		return PLAYLIST_RESULT_ERRNO;

	for (unsigned i = 0; i < queue_length(&playlist.queue); i++)
		playlist_print_song(fp, queue_get(&playlist.queue, i));

	while (fclose(fp) && errno == EINTR) ;

	idle_add(IDLE_STORED_PLAYLIST);
	return PLAYLIST_RESULT_SUCCESS;
}

int getPlaylistCurrentSong(void)
{
	if (playlist.current >= 0)
		return queue_order_to_position(&playlist.queue,
					       playlist.current);

	return -1;
}

unsigned long getPlaylistVersion(void)
{
	return playlist.queue.version;
}

int getPlaylistLength(void)
{
	return queue_length(&playlist.queue);
}

enum playlist_result seekSongInPlaylist(unsigned song, float seek_time)
{
	unsigned i;
	int ret;

	if (!queue_valid_position(&playlist.queue, song))
		return PLAYLIST_RESULT_BAD_RANGE;

	if (playlist.queue.random)
		i = queue_position_to_order(&playlist.queue, song);
	else
		i = song;

	clearPlayerError();
	playlist.stop_on_error = true;
	playlist.error_count = 0;

	if (playlist.playing) {
		if (playlist.queued >= 0)
			clearPlayerQueue();
	} else
		playPlaylistOrderNumber(i);

	if (playlist.current != (int)i) {
		playPlaylistOrderNumber(i);
	}

	ret = playerSeek(queue_get_order(&playlist.queue, i), seek_time);
	if (ret < 0)
		return PLAYLIST_RESULT_NOT_PLAYING;

	return PLAYLIST_RESULT_SUCCESS;
}

enum playlist_result seekSongInPlaylistById(unsigned id, float seek_time)
{
	int song = queue_id_to_position(&playlist.queue, id);
	if (song < 0)
		return PLAYLIST_RESULT_NO_SUCH_SONG;

	return seekSongInPlaylist(song, seek_time);
}

unsigned getPlaylistSongId(unsigned song)
{
	return queue_position_to_id(&playlist.queue, song);
}

enum playlist_result loadPlaylist(const char *utf8file)
{
	GPtrArray *list;

	if (!(list = spl_load(utf8file)))
		return PLAYLIST_RESULT_NO_SUCH_LIST;

	for (unsigned i = 0; i < list->len; ++i) {
		const char *temp = g_ptr_array_index(list, i);
		if ((addToPlaylist(temp, NULL)) != PLAYLIST_RESULT_SUCCESS) {
			/* for windows compatibility, convert slashes */
			char *temp2 = g_strdup(temp);
			char *p = temp2;
			while (*p) {
				if (*p == '\\')
					*p = '/';
				p++;
			}
			if ((addToPlaylist(temp, NULL)) != PLAYLIST_RESULT_SUCCESS) {
				g_warning("can't add file \"%s\"", temp2);
			}
			free(temp2);
		}
	}

	spl_free(list);
	return PLAYLIST_RESULT_SUCCESS;
}

/*
 * Not supporting '/' was done out of laziness, and we should really
 * strive to support it in the future.
 *
 * Not supporting '\r' and '\n' is done out of protocol limitations (and
 * arguably laziness), but bending over head over heels to modify the
 * protocol (and compatibility with all clients) to support idiots who
 * put '\r' and '\n' in filenames isn't going to happen, either.
 */
int is_valid_playlist_name(const char *utf8path)
{
	return strchr(utf8path, '/') == NULL &&
		strchr(utf8path, '\n') == NULL &&
		strchr(utf8path, '\r') == NULL;
}