Song.hxx

/*
 * Copyright 2003-2020 The Music Player Daemon Project
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef MPD_SONG_HXX
#define MPD_SONG_HXX

#include "Ptr.hxx"
#include "Chrono.hxx"
#include "tag/Tag.hxx"
#include "pcm/AudioFormat.hxx"
#include "util/Compiler.h"
#include "config.h"

#include <boost/intrusive/list.hpp>

#include <string>

struct StringView;
struct LightSong;
struct Directory;
class DetachedSong;
class Storage;
class ArchiveFile;

/**
 * A song file inside the configured music directory.  Internal
 * #SimpleDatabase class.
 */
struct Song {
	static constexpr auto link_mode = boost::intrusive::normal_link;
	typedef boost::intrusive::link_mode<link_mode> LinkMode;
	typedef boost::intrusive::list_member_hook<LinkMode> Hook;

	/**
	 * Pointers to the siblings of this directory within the
	 * parent directory.  It is unused (undefined) if this song is
	 * not in the database.
	 *
	 * This attribute is protected with the global #db_mutex.
	 * Read access in the update thread does not need protection.
	 */
	Hook siblings;

	Tag tag;

	/**
	 * The #Directory that contains this song.
	 */
	Directory &parent;

	/**
	 * The time stamp of the last file modification.  A negative
	 * value means that this is unknown/unavailable.
	 */
	std::chrono::system_clock::time_point mtime =
		std::chrono::system_clock::time_point::min();

	/**
	 * Start of this sub-song within the file.
	 */
	SongTime start_time = SongTime::zero();

	/**
	 * End of this sub-song within the file.
	 * Unused if zero.
	 */
	SongTime end_time = SongTime::zero();

	/**
	 * The audio format of the song, if given by the decoder
	 * plugin.  May be undefined if unknown.
	 */
	AudioFormat audio_format = AudioFormat::Undefined();

	/**
	 * The file name.
	 */
	std::string filename;

	/**
	 * If non-empty, then this object does not describe a file
	 * within the `music_directory`, but some sort of symbolic
	 * link pointing to this value.  It can be an absolute URI
	 * (i.e. with URI scheme) or a URI relative to this object
	 * (which may begin with one or more "../").
	 */
	std::string target;

	template<typename F>
	Song(F &&_filename, Directory &_parent) noexcept
		:parent(_parent), filename(std::forward<F>(_filename)) {}

	Song(DetachedSong &&other, Directory &_parent) noexcept;

	/**
	 * allocate a new song structure with a local file name and attempt to
	 * load its metadata.  If all decoder plugin fail to read its meta
	 * data, nullptr is returned.
	 *
	 * Throws on error.
	 *
	 * @return the song on success, nullptr if the file was not
	 * recognized
	 */
	static SongPtr LoadFile(Storage &storage, const char *name_utf8,
				Directory &parent);

	/**
	 * Throws on error.
	 *
	 * @return true on success, false if the file was not recognized
	 */
	bool UpdateFile(Storage &storage);

#ifdef ENABLE_ARCHIVE
	static SongPtr LoadFromArchive(ArchiveFile &archive,
				       const char *name_utf8,
				       Directory &parent) noexcept;
	bool UpdateFileInArchive(ArchiveFile &archive) noexcept;
#endif

	/**
	 * Returns the URI of the song in UTF-8 encoding, including its
	 * location within the music directory.
	 */
	gcc_pure
	std::string GetURI() const noexcept;

	gcc_pure
	LightSong Export() const noexcept;
};

typedef boost::intrusive::list<Song,
			       boost::intrusive::member_hook<Song, Song::Hook,
							     &Song::siblings>,
			       boost::intrusive::constant_time_size<false>> SongList;

#endif