ProxyDatabasePlugin: new database plugin using libmpdclient

Implementation incomplete, but sort-of-works.  DumpDatabase works, but
MPD is still hard-coded on the "simple" plugin.

Makefile.am

@@ -20,6 +20,7 @@ noinst_LIBRARIES = \
 	liboutput_plugins.a
 
 src_mpd_CPPFLAGS = $(AM_CPPFLAGS) \
+	$(LIBMPDCLIENT_CFLAGS) \
 	$(AVAHI_CFLAGS) \
 	$(LIBWRAP_CFLAGS) \
 	$(SQLITE_CFLAGS)
@@ -437,7 +438,13 @@ libdb_plugins_a_SOURCES = \
 	src/DatabaseRegistry.cxx src/DatabaseRegistry.hxx \
 	src/db/SimpleDatabasePlugin.cxx src/db/SimpleDatabasePlugin.hxx
 
+if HAVE_LIBMPDCLIENT
+libdb_plugins_a_SOURCES += \
+	src/db/ProxyDatabasePlugin.cxx src/db/ProxyDatabasePlugin.hxx
+endif
+
 DB_LIBS = \
+	$(LIBMPDCLIENT_LIBS) \
 	libdb_plugins.a
 
 # archive plugins
@@ -1043,7 +1050,7 @@ test_run_resolver_SOURCES = test/run_resolver.c \
 	src/resolver.c
 
 test_DumpDatabase_LDADD = \
-	libdb_plugins.a \
+	$(DB_LIBS) \
 	libutil.a \
 	$(GLIB_LIBS)
 test_DumpDatabase_SOURCES = test/DumpDatabase.cxx \

configure.ac

@@ -144,6 +144,12 @@ AC_CHECK_HEADERS(valgrind/memcheck.h)
 dnl ---------------------------------------------------------------------------
 dnl Allow tools to be specifically built
 dnl ---------------------------------------------------------------------------
+
+AC_ARG_ENABLE(mpdclient,
+	AS_HELP_STRING([--enable-libmpdclient],
+		[enable support for the MPD client]),,
+	enable_libmpdclient=auto)
+
 AC_ARG_ENABLE(alsa,
 	AS_HELP_STRING([--enable-alsa], [enable ALSA support]),,
 	[enable_alsa=auto])
@@ -534,6 +540,15 @@ dnl ---------------------------------------------------------------------------
 dnl Miscellaneous Libraries
 dnl ---------------------------------------------------------------------------
 
+dnl -------------------------------- libmpdclient --------------------------------
+MPD_AUTO_PKG(libmpdclient, LIBMPDCLIENT, [libmpdclient >= 2.2],
+	[MPD client library], [libmpdclient not found])
+if test x$enable_libmpdclient = xyes; then
+	AC_DEFINE(HAVE_LIBMPDCLIENT, 1, [Define to use libmpdclient])
+fi
+
+AM_CONDITIONAL(HAVE_LIBMPDCLIENT, test x$enable_libmpdclient = xyes)
+
 dnl --------------------------------- inotify ---------------------------------
 AC_CHECK_FUNCS(inotify_init inotify_init1)
 

src/DatabaseRegistry.cxx

@@ -17,13 +17,18 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include "config.h"
 #include "DatabaseRegistry.hxx"
 #include "db/SimpleDatabasePlugin.hxx"
+#include "db/ProxyDatabasePlugin.hxx"
 
 #include <string.h>
 
 const DatabasePlugin *const database_plugins[] = {
 	&simple_db_plugin,
+#ifdef HAVE_LIBMPDCLIENT
+	&proxy_db_plugin,
+#endif
 	NULL
 };
 

src/db/ProxyDatabasePlugin.cxx

@@ -0,0 +1,345 @@
+/*
+ * 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 "gcc.h"
+
+extern "C" {
+#include "db_error.h"
+#include "db_visitor.h"
+#include "db_save.h"
+#include "db_lock.h"
+#include "conf.h"
+#include "song.h"
+#include "tag.h"
+}
+
+#include "directory.h"
+#include "playlist_vector.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;
+
+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 bool Visit(const DatabaseSelection &selection,
+			   VisitDirectory visit_directory,
+			   VisitSong visit_song,
+			   VisitPlaylist visit_playlist,
+			   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 bool
+CheckError(const 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));
+	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;
+	}
+
+	return true;
+}
+
+void
+ProxyDatabase::Close()
+{
+	assert(connection != nullptr);
+
+	mpd_connection_free(connection);
+}
+
+struct song *
+ProxyDatabase::GetSong(const char *uri, GError **error_r) const
+{
+	// TODO: implement
+	// TODO: auto-reconnect
+
+	g_set_error(error_r, db_quark(), DB_NOT_FOUND,
+		    "No such song: %s", uri);
+	return nullptr;
+}
+
+static bool
+Visit(struct mpd_connection *connection, directory &parent,
+      bool recursive, VisitDirectory visit_directory, VisitSong visit_song,
+      VisitPlaylist visit_playlist, GError **error_r);
+
+static bool
+Visit(struct mpd_connection *connection, directory &parent,
+      bool recursive, const struct mpd_directory *directory,
+      VisitDirectory visit_directory, VisitSong visit_song,
+      VisitPlaylist visit_playlist, GError **error_r)
+{
+	if (!recursive && !visit_directory)
+		return true;
+
+	struct directory *d =
+		directory_new(mpd_directory_get_path(directory), &parent);
+
+	bool success = (!visit_directory || visit_directory(*d, error_r)) &&
+		Visit(connection, *d, recursive,
+		      visit_directory, visit_song, visit_playlist, error_r);
+	directory_free(d);
+
+	return success;
+}
+
+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(struct directory &parent, const struct mpd_song *song)
+{
+	char *name = g_path_get_basename(mpd_song_get_uri(song));
+	struct song *s = song_file_new(name, &parent);
+	g_free(name);
+
+	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);
+
+	static constexpr struct {
+		enum tag_type d;
+		enum mpd_tag_type s;
+	} 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 }
+	};
+
+	tag_begin_add(tag);
+	for (auto i = 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(struct directory &parent, const struct mpd_song *song,
+      VisitSong visit_song, GError **error_r)
+{
+	if (!visit_song)
+		return true;
+
+	struct song *s = Convert(parent, song);
+	bool success = visit_song(*s, error_r);
+	song_free(s);
+
+	return success;
+}
+
+static bool
+Visit(struct directory &parent, const struct mpd_playlist *playlist,
+      VisitPlaylist visit_playlist, GError **error_r)
+{
+	if (!visit_playlist)
+		return true;
+
+	char *name = g_path_get_basename(mpd_playlist_get_path(playlist));
+	struct playlist_metadata p;
+	p.name = name;
+	p.mtime = mpd_playlist_get_last_modified(playlist);
+
+	bool success = visit_playlist(p, parent, error_r);
+	g_free(name);
+
+	return success;
+}
+
+static std::list<struct mpd_entity *>
+ReceiveEntities(struct mpd_connection *connection)
+{
+	std::list<struct mpd_entity *> entities;
+	struct mpd_entity *entity;
+	while ((entity = mpd_recv_entity(connection)) != NULL)
+		entities.push_back(entity);
+
+	mpd_response_finish(connection);
+	return entities;
+}
+
+static bool
+Visit(struct mpd_connection *connection, struct directory &parent,
+      bool recursive, VisitDirectory visit_directory, VisitSong visit_song,
+      VisitPlaylist visit_playlist, GError **error_r)
+{
+	if (!mpd_send_list_meta(connection, directory_get_path(&parent)))
+		return CheckError(connection, error_r);
+
+	std::list<struct mpd_entity *> entities = ReceiveEntities(connection);
+	if (!CheckError(connection, error_r)) {
+		for (auto entity : entities)
+			mpd_entity_free(entity);
+		return false;
+	}
+
+	for (auto entity : entities) {
+		switch (mpd_entity_get_type(entity)) {
+		case MPD_ENTITY_TYPE_UNKNOWN:
+			break;
+
+		case MPD_ENTITY_TYPE_DIRECTORY:
+			Visit(connection, parent, recursive,
+			      mpd_entity_get_directory(entity),
+			      visit_directory, visit_song, visit_playlist,
+			      error_r);
+			break;
+
+		case MPD_ENTITY_TYPE_SONG:
+			Visit(parent, mpd_entity_get_song(entity), visit_song,
+			      error_r);
+			break;
+
+		case MPD_ENTITY_TYPE_PLAYLIST:
+			Visit(parent, mpd_entity_get_playlist(entity),
+			      visit_playlist, error_r);
+			break;
+		}
+
+		mpd_entity_free(entity);
+	}
+
+	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
+
+	struct directory *parent = directory_new(selection.uri, nullptr);
+	bool success = ::Visit(connection, *parent, selection.recursive,
+			       visit_directory, visit_song, visit_playlist,
+			       error_r);
+	directory_free(parent);
+	return success;
+}
+
+const DatabasePlugin proxy_db_plugin = {
+	"proxy",
+	ProxyDatabase::Create,
+};

src/db/ProxyDatabasePlugin.hxx

@@ -0,0 +1,27 @@
+/*
+ * 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.
+ */
+
+#ifndef MPD_PROXY_DATABASE_PLUGIN_HXX
+#define MPD_PROXY_DATABASE_PLUGIN_HXX
+
+struct DatabasePlugin;
+
+extern const DatabasePlugin proxy_db_plugin;
+
+#endif