mpd/src/db/ProxyDatabasePlugin.cxx

/*
 * Copyright (C) 2003-2012 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 "config.h"
#include "ProxyDatabasePlugin.hxx"
#include "DatabasePlugin.hxx"
#include "DatabaseSelection.hxx"
#include "PlaylistVector.hxx"
#include "Directory.hxx"
#include "gcc.h"

extern "C" {
#include "db_error.h"
#include "conf.h"
#include "song.h"
#include "tag.h"
}

#undef MPD_DIRECTORY_H
#undef MPD_SONG_H
#include <mpd/client.h>

#include <cassert>
#include <string>
#include <list>

class ProxyDatabase : public Database {
	std::string host;
	unsigned port;

	struct mpd_connection *connection;
	struct directory *root;

public:
	static Database *Create(const struct config_param *param,
				GError **error_r);

	virtual bool Open(GError **error_r) override;
	virtual void Close() override;
	virtual struct song *GetSong(const char *uri_utf8,
				     GError **error_r) const override;
	virtual void ReturnSong(struct song *song) const;

	virtual bool Visit(const DatabaseSelection &selection,
			   VisitDirectory visit_directory,
			   VisitSong visit_song,
			   VisitPlaylist visit_playlist,
			   GError **error_r) const override;

	virtual bool VisitUniqueTags(const DatabaseSelection &selection,
				     enum tag_type tag_type,
				     VisitString visit_string,
				     GError **error_r) const override;

	virtual bool GetStats(const DatabaseSelection &selection,
			      DatabaseStats &stats,
			      GError **error_r) const override;

protected:
	bool Configure(const struct config_param *param, GError **error_r);
};

G_GNUC_CONST
static inline GQuark
libmpdclient_quark(void)
{
	return g_quark_from_static_string("libmpdclient");
}

static constexpr struct {
	enum tag_type d;
	enum mpd_tag_type s;
} tag_table[] = {
	{ TAG_ARTIST, MPD_TAG_ARTIST },
	{ TAG_ALBUM, MPD_TAG_ALBUM },
	{ TAG_ALBUM_ARTIST, MPD_TAG_ALBUM_ARTIST },
	{ TAG_TITLE, MPD_TAG_TITLE },
	{ TAG_TRACK, MPD_TAG_TRACK },
	{ TAG_NAME, MPD_TAG_NAME },
	{ TAG_GENRE, MPD_TAG_GENRE },
	{ TAG_DATE, MPD_TAG_DATE },
	{ TAG_COMPOSER, MPD_TAG_COMPOSER },
	{ TAG_PERFORMER, MPD_TAG_PERFORMER },
	{ TAG_COMMENT, MPD_TAG_COMMENT },
	{ TAG_DISC, MPD_TAG_DISC },
	{ TAG_MUSICBRAINZ_ARTISTID, MPD_TAG_MUSICBRAINZ_ARTISTID },
	{ TAG_MUSICBRAINZ_ALBUMID, MPD_TAG_MUSICBRAINZ_ALBUMID },
	{ TAG_MUSICBRAINZ_ALBUMARTISTID,
	  MPD_TAG_MUSICBRAINZ_ALBUMARTISTID },
	{ TAG_MUSICBRAINZ_TRACKID, MPD_TAG_MUSICBRAINZ_TRACKID },
	{ TAG_NUM_OF_ITEM_TYPES, MPD_TAG_COUNT }
};

G_GNUC_CONST
static enum mpd_tag_type
Convert(enum tag_type tag_type)
{
	for (auto i = tag_table; i->d != TAG_NUM_OF_ITEM_TYPES; ++i)
		if (i->d == tag_type)
			return i->s;

	return MPD_TAG_COUNT;
}

static bool
CheckError(struct mpd_connection *connection, GError **error_r)
{
	const auto error = mpd_connection_get_error(connection);
	if (error == MPD_ERROR_SUCCESS)
		return true;

	g_set_error_literal(error_r, libmpdclient_quark(), (int)error,
			    mpd_connection_get_error_message(connection));
	mpd_connection_clear_error(connection);
	return false;
}

Database *
ProxyDatabase::Create(const struct config_param *param, GError **error_r)
{
	ProxyDatabase *db = new ProxyDatabase();
	if (!db->Configure(param, error_r)) {
		delete db;
		db = NULL;
	}

	return db;
}

bool
ProxyDatabase::Configure(const struct config_param *param, GError **)
{
	host = config_get_block_string(param, "host", "");
	port = config_get_block_unsigned(param, "port", 0);

	return true;
}

bool
ProxyDatabase::Open(GError **error_r)
{
	connection = mpd_connection_new(host.empty() ? NULL : host.c_str(),
					port, 0);
	if (connection == NULL) {
		g_set_error_literal(error_r, libmpdclient_quark(),
				    (int)MPD_ERROR_OOM, "Out of memory");
		return false;
	}

	if (!CheckError(connection, error_r)) {
		mpd_connection_free(connection);
		return false;
	}

	root = directory::NewRoot();

	return true;
}

void
ProxyDatabase::Close()
{
	assert(connection != nullptr);

	root->Free();
	mpd_connection_free(connection);
}

static song *
Convert(const struct mpd_song *song);

struct song *
ProxyDatabase::GetSong(const char *uri, GError **error_r) const
{
	// TODO: implement
	// TODO: auto-reconnect

	if (!mpd_send_list_meta(connection, uri)) {
		CheckError(connection, error_r);
		return nullptr;
	}

	struct mpd_song *song = mpd_recv_song(connection);
	struct song *song2 = song != nullptr
		? Convert(song)
		: nullptr;
	mpd_song_free(song);
	if (!mpd_response_finish(connection)) {
		if (song2 != nullptr)
			song_free(song2);

		CheckError(connection, error_r);
		return nullptr;
	}

	if (song2 == nullptr)
		g_set_error(error_r, db_quark(), DB_NOT_FOUND,
			    "No such song: %s", uri);

	return song2;
}

void
ProxyDatabase::ReturnSong(struct song *song) const
{
	assert(song != nullptr);
	assert(song_in_database(song));
	assert(song_is_detached(song));

	song_free(song);
}

static bool
Visit(struct mpd_connection *connection, const char *uri,
      bool recursive, VisitDirectory visit_directory, VisitSong visit_song,
      VisitPlaylist visit_playlist, GError **error_r);

static bool
Visit(struct mpd_connection *connection,
      bool recursive, const struct mpd_directory *directory,
      VisitDirectory visit_directory, VisitSong visit_song,
      VisitPlaylist visit_playlist, GError **error_r)
{
	const char *path = mpd_directory_get_path(directory);

	if (visit_directory) {
		struct directory *d =
			directory::NewGeneric(path, &detached_root);
		bool success = visit_directory(*d, error_r);
		d->Free();
		if (!success)
			return false;
	}

	if (recursive &&
	    !Visit(connection, path, recursive,
		   visit_directory, visit_song, visit_playlist, error_r))
		return false;

	return true;
}

static void
Copy(struct tag *tag, enum tag_type d_tag,
     const struct mpd_song *song, enum mpd_tag_type s_tag)
{

	for (unsigned i = 0;; ++i) {
		const char *value = mpd_song_get_tag(song, s_tag, i);
		if (value == NULL)
			break;

		tag_add_item(tag, d_tag, value);
	}
}

static song *
Convert(const struct mpd_song *song)
{
	struct song *s = song_detached_new(mpd_song_get_uri(song));

	s->mtime = mpd_song_get_last_modified(song);
	s->start_ms = mpd_song_get_start(song) * 1000;
	s->end_ms = mpd_song_get_end(song) * 1000;

	struct tag *tag = tag_new();
	tag->time = mpd_song_get_duration(song);

	tag_begin_add(tag);
	for (auto i = tag_table; i->d != TAG_NUM_OF_ITEM_TYPES; ++i)
		Copy(tag, i->d, song, i->s);
	tag_end_add(tag);

	s->tag = tag;

	return s;
}

static bool
Visit(const struct mpd_song *song,
      VisitSong visit_song, GError **error_r)
{
	if (!visit_song)
		return true;

	struct song *s = Convert(song);
	bool success = visit_song(*s, error_r);
	song_free(s);

	return success;
}

static bool
Visit(const struct mpd_playlist *playlist,
      VisitPlaylist visit_playlist, GError **error_r)
{
	if (!visit_playlist)
		return true;

	PlaylistInfo p(mpd_playlist_get_path(playlist),
		       mpd_playlist_get_last_modified(playlist));

	return visit_playlist(p, detached_root, error_r);
}

class ProxyEntity {
	struct mpd_entity *entity;

public:
	explicit ProxyEntity(struct mpd_entity *_entity)
		:entity(_entity) {}

	ProxyEntity(const ProxyEntity &other) = delete;

	ProxyEntity(ProxyEntity &&other)
		:entity(other.entity) {
		other.entity = nullptr;
	}

	~ProxyEntity() {
		if (entity != nullptr)
			mpd_entity_free(entity);
	}

	ProxyEntity &operator=(const ProxyEntity &other) = delete;

	operator const struct mpd_entity *() const {
		return entity;
	}
};

static std::list<ProxyEntity>
ReceiveEntities(struct mpd_connection *connection)
{
	std::list<ProxyEntity> entities;
	struct mpd_entity *entity;
	while ((entity = mpd_recv_entity(connection)) != NULL)
		entities.push_back(ProxyEntity(entity));

	mpd_response_finish(connection);
	return entities;
}

static bool
Visit(struct mpd_connection *connection, const char *uri,
      bool recursive, VisitDirectory visit_directory, VisitSong visit_song,
      VisitPlaylist visit_playlist, GError **error_r)
{
	if (!mpd_send_list_meta(connection, uri))
		return CheckError(connection, error_r);

	std::list<ProxyEntity> entities(ReceiveEntities(connection));
	if (!CheckError(connection, error_r))
		return false;

	for (const auto &entity : entities) {
		switch (mpd_entity_get_type(entity)) {
		case MPD_ENTITY_TYPE_UNKNOWN:
			break;

		case MPD_ENTITY_TYPE_DIRECTORY:
			if (!Visit(connection, recursive,
				   mpd_entity_get_directory(entity),
				   visit_directory, visit_song, visit_playlist,
				   error_r))
				return false;
			break;

		case MPD_ENTITY_TYPE_SONG:
			if (!Visit(mpd_entity_get_song(entity), visit_song,
				   error_r))
				return false;
			break;

		case MPD_ENTITY_TYPE_PLAYLIST:
			if (!Visit(mpd_entity_get_playlist(entity),
				   visit_playlist, error_r))
				return false;
			break;
		}
	}

	return CheckError(connection, error_r);
}

bool
ProxyDatabase::Visit(const DatabaseSelection &selection,
		     VisitDirectory visit_directory,
		     VisitSong visit_song,
		     VisitPlaylist visit_playlist,
		     GError **error_r) const
{
	// TODO: match
	// TODO: auto-reconnect

	return ::Visit(connection, selection.uri, selection.recursive,
		       visit_directory, visit_song, visit_playlist,
		       error_r);
}

bool
ProxyDatabase::VisitUniqueTags(const DatabaseSelection &selection,
			       enum tag_type tag_type,
			       VisitString visit_string,
			       GError **error_r) const
{
	enum mpd_tag_type tag_type2 = Convert(tag_type);
	if (tag_type2 == MPD_TAG_COUNT) {
		g_set_error_literal(error_r, libmpdclient_quark(), 0,
				    "Unsupported tag");
		return false;
	}

	if (!mpd_search_db_tags(connection, tag_type2))
		return CheckError(connection, error_r);

	// TODO: match
	(void)selection;

	if (!mpd_search_commit(connection))
		return CheckError(connection, error_r);

	bool result = true;

	struct mpd_pair *pair;
	while (result &&
	       (pair = mpd_recv_pair_tag(connection, tag_type2)) != nullptr) {
		result = visit_string(pair->value, error_r);
		mpd_return_pair(connection, pair);
	}

	return mpd_response_finish(connection) &&
		CheckError(connection, error_r) &&
		result;
}

bool
ProxyDatabase::GetStats(const DatabaseSelection &selection,
			DatabaseStats &stats, GError **error_r) const
{
	// TODO: match
	(void)selection;

	struct mpd_stats *stats2 =
		mpd_run_stats(connection);
	if (stats2 == nullptr)
		return CheckError(connection, error_r);

	stats.song_count = mpd_stats_get_number_of_songs(stats2);
	stats.total_duration = mpd_stats_get_db_play_time(stats2);
	stats.artist_count = mpd_stats_get_number_of_artists(stats2);
	stats.album_count = mpd_stats_get_number_of_albums(stats2);
	mpd_stats_free(stats2);

	return true;
}

const DatabasePlugin proxy_db_plugin = {
	"proxy",
	ProxyDatabase::Create,
};