Song.cxx

/*
 * Copyright 2003-2021 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.
 */

#include "Song.hxx"
#include "ExportedSong.hxx"
#include "Directory.hxx"
#include "tag/Tag.hxx"
#include "tag/Builder.hxx"
#include "song/DetachedSong.hxx"
#include "song/LightSong.hxx"
#include "fs/Traits.hxx"
#include "time/ChronoUtil.hxx"
#include "util/IterableSplitString.hxx"

Song::Song(DetachedSong &&other, Directory &_parent) noexcept
	:parent(_parent),
	 filename(other.GetURI()),
	 tag(std::move(other.WritableTag())),
	 mtime(other.GetLastModified()),
	 start_time(other.GetStartTime()),
	 end_time(other.GetEndTime()),
	 audio_format(other.GetAudioFormat())
{
}

const char *
Song::GetFilenameSuffix() const noexcept
{
	return target.empty()
		? PathTraitsUTF8::GetFilenameSuffix(filename.c_str())
		: PathTraitsUTF8::GetPathSuffix(target.c_str());
}

std::string
Song::GetURI() const noexcept
{
	if (parent.IsRoot())
		return filename;
	else {
		const char *path = parent.GetPath();
		return PathTraitsUTF8::Build(path, filename);
	}
}

/**
 * Path name traversal of a #Directory.
 */
gcc_pure
static const Directory *
FindTargetDirectory(const Directory &base, StringView path) noexcept
{
	const auto *directory = &base;
	for (const StringView name : IterableSplitString(path, '/')) {
		if (name.empty() || name.Equals("."))
			continue;

		directory = name.Equals("..")
			? directory->parent
			: directory->FindChild(name);
		if (directory == nullptr)
			break;
	}

	return directory;
}

/**
 * Path name traversal of a #Song.
 */
gcc_pure
static const Song *
FindTargetSong(const Directory &_directory, StringView target) noexcept
{
	auto [path, last] = target.SplitLast('/');
	if (last == nullptr) {
		last = path;
		path = nullptr;
	}

	if (last.empty())
		return nullptr;

	const auto *directory = FindTargetDirectory(_directory, path);
	if (directory == nullptr)
		return nullptr;

	return directory->FindSong(last);
}

ExportedSong
Song::Export() const noexcept
{
	const auto *target_song = !target.empty()
		? FindTargetSong(parent, (std::string_view)target)
		: nullptr;

	Tag merged_tag;
	if (target_song != nullptr) {
		/* if we found the target song (which may be the
		   underlying song file of a CUE file), merge the tags
		   from that song with this song's tags (from the CUE
		   file) */
		TagBuilder builder(tag);
		builder.Complement(target_song->tag);
		merged_tag = builder.Commit();
	}

	ExportedSong dest = merged_tag.IsDefined()
		? ExportedSong(filename.c_str(), std::move(merged_tag))
		: ExportedSong(filename.c_str(), tag);
	if (!parent.IsRoot())
		dest.directory = parent.GetPath();
	if (!target.empty())
		dest.real_uri = target.c_str();
	dest.mtime = IsNegative(mtime) && target_song != nullptr
		? target_song->mtime
		: mtime;
	dest.start_time = start_time.IsZero() && target_song != nullptr
		? target_song->start_time
		: start_time;
	dest.end_time = end_time.IsZero() && target_song != nullptr
		? target_song->end_time
		: end_time;
	dest.audio_format = audio_format.IsDefined() || target_song == nullptr
		? audio_format
		: target_song->audio_format;
	return dest;
}