[gnome-music/wip/jfelder/mpris-cleanup: 45/67] mpris: Cleanup _get_metadata method

[Jean Felder <jfelder src gnome org>]

commit b58cbc455f79b0c5cebba68a8108d2891ba0ce72
Author: Jean Felder <jfelder src gnome org>
Date:   Tue Sep 4 19:05:30 2018 +0200

    mpris: Cleanup _get_metadata method
    
    Do not allow a default media parameter equal to None. It creates
    counter intuitive checks at the start of the function.
    Update codestyle.
    Do not use exceptions.
    Most of the media properties cannot be None (length, track_number,
    play_count, title).
    
    In case no media can be found, set 'mpris:trackid' to the 'NoTrack'
    path and return it.

 gnomemusic/mpris.py | 102 ++++++++++++++++++----------------------------------
 1 file changed, 35 insertions(+), 67 deletions(-)
---
diff --git a/gnomemusic/mpris.py b/gnomemusic/mpris.py
index fe9c9649..56b758f3 100644
--- a/gnomemusic/mpris.py
+++ b/gnomemusic/mpris.py
@@ -294,77 +294,41 @@ class MPRIS(DBusInterface):
             return 'Playlist'
 
     @log
-    def _get_metadata(self, media=None):
-        if not media:
-            media = self.player.props.current_song
+    def _get_metadata(self, media):
+        song_dbus_path = self._get_song_dbus_path(media)
         if not media:
-            return {}
+            return {
+                'mpris:trackid': GLib.Variant('o', song_dbus_path)
+            }
+
+        length = media.get_duration() * 1e6
+        user_rating = 1.0 if media.get_favourite() else 0.0
+        artist = utils.get_artist_name(media)
 
-        song_dbus_path = self._get_song_dbus_path(media)
         metadata = {
             'mpris:trackid': GLib.Variant('o', song_dbus_path),
-            'xesam:url': GLib.Variant('s', media.get_url())
+            'xesam:url': GLib.Variant('s', media.get_url()),
+            'mpris:length': GLib.Variant('x', length),
+            'xesam:trackNumber': GLib.Variant('i', media.get_track_number()),
+            'xesam:useCount': GLib.Variant('i', media.get_play_count()),
+            'xesam:userRating': GLib.Variant('d', user_rating),
+            'xesam:title': GLib.Variant('s', utils.get_media_title(media)),
+            'xesam:album': GLib.Variant('s', utils.get_album_title(media)),
+            'xesam:artist': GLib.Variant('as', [artist]),
+            'xesam:albumArtist': GLib.Variant('as', [artist])
         }
 
-        try:
-            length = media.get_duration() * 1000000
-            assert length is not None
-            metadata['mpris:length'] = GLib.Variant('x', length)
-        except:
-            pass
-
-        try:
-            trackNumber = media.get_track_number()
-            assert trackNumber is not None
-            metadata['xesam:trackNumber'] = GLib.Variant('i', trackNumber)
-        except:
-            pass
-
-        try:
-            useCount = media.get_play_count()
-            assert useCount is not None
-            metadata['xesam:useCount'] = GLib.Variant('i', useCount)
-        except:
-            pass
-
-        user_rating = 1.0 if media.get_favourite() else 0.0
-        metadata['xesam:userRating'] = GLib.Variant('d', user_rating)
+        genre = media.get_genre()
+        if genre is not None:
+            metadata['xesam:genre'] = GLib.Variant('as', [genre])
 
-        try:
-            title = utils.get_media_title(media)
-            assert title is not None
-            metadata['xesam:title'] = GLib.Variant('s', title)
-        except:
-            pass
+        last_played = media.get_last_played()
+        if last_played is not None:
+            metadata['xesam:lastUsed'] = GLib.Variant('s', last_played)
 
-
-        album = utils.get_album_title(media)
-        metadata['xesam:album'] = GLib.Variant('s', album)
-
-        artist = utils.get_artist_name(media)
-        metadata['xesam:artist'] = GLib.Variant('as', [artist])
-        metadata['xesam:albumArtist'] = GLib.Variant('as', [artist])
-
-        try:
-            genre = media.get_genre()
-            assert genre is not None
-            metadata['xesam:genre'] = GLib.Variant('as', genre)
-        except:
-            pass
-
-        try:
-            lastUsed = media.get_last_played()
-            assert lastUsed is not None
-            metadata['xesam:lastUsed'] = GLib.Variant('s', lastUsed)
-        except:
-            pass
-
-        try:
-            artUrl = media.get_thumbnail()
-            assert artUrl is not None
-            metadata['mpris:artUrl'] = GLib.Variant('s', artUrl)
-        except:
-            pass
+        art_url = media.get_thumbnail()
+        if art_url is not None:
+            metadata['mpris:artUrl'] = GLib.Variant('s', art_url)
 
         return metadata
 
@@ -477,22 +441,24 @@ class MPRIS(DBusInterface):
 
         has_next = self.player.props.has_next
         has_previous = self.player.props.has_previous
+        metadata = self._get_metadata(self.player.props.current_song)
         self.PropertiesChanged(MPRIS.MEDIA_PLAYER2_PLAYER_IFACE,
                                {
-                                   'Metadata': GLib.Variant('a{sv}', self._get_metadata()),
                                    'CanGoNext': GLib.Variant('b', has_next),
                                    'CanGoPrevious': GLib.Variant(
                                        'b', has_previous),
                                    'CanPlay': GLib.Variant('b', True),
                                    'CanPause': GLib.Variant('b', True),
+                                   'Metadata': GLib.Variant('a{sv}', metadata),
                                },
                                [])
 
     @log
     def _on_thumbnail_updated(self, player, data=None):
+        metadata = self._get_metadata(self.player.props.current_song)
         self.PropertiesChanged(MPRIS.MEDIA_PLAYER2_PLAYER_IFACE,
                                {
-                                   'Metadata': GLib.Variant('a{sv}', self._get_metadata()),
+                                   'Metadata': GLib.Variant('a{sv}', metadata),
                                },
                                [])
 
@@ -619,7 +585,8 @@ class MPRIS(DBusInterface):
         :param str track_id: The currently playing track's identifier
         :param int position_msecond: new position in microseconds
         """
-        if track_id != self._get_metadata().get('mpris:trackid').get_string():
+        current_track_id = self._get_metadata(self.player.props.current_song)
+        if current_track_id != current_track_id.get_string():
             return
         self.player.set_position(position_msecond / 1e6)
 
@@ -731,12 +698,13 @@ class MPRIS(DBusInterface):
             }
         elif interface_name == MPRIS.MEDIA_PLAYER2_PLAYER_IFACE:
             position_msecond = int(self.player.get_position() * 1e6)
+            metadata = self._get_metadata(self.player.props.current_song)
             return {
                 'PlaybackStatus': GLib.Variant('s', self._get_playback_status()),
                 'LoopStatus': GLib.Variant('s', self._get_loop_status()),
                 'Rate': GLib.Variant('d', 1.0),
                 'Shuffle': GLib.Variant('b', self.player.props.repeat_mode == RepeatMode.SHUFFLE),
-                'Metadata': GLib.Variant('a{sv}', self._get_metadata()),
+                'Metadata': GLib.Variant('a{sv}', metadata),
                 'Volume': GLib.Variant('d', self.player.get_volume()),
                 'Position': GLib.Variant('x', position_msecond),
                 'MinimumRate': GLib.Variant('d', 1.0),