[gnome-music/wip/mschraal/remove-playlists-loaded-signal] Let consumers handle playlists availability

[Marinus Schraal <mschraal src gnome org>]

commit ee84d046d20afc4a5a882089169d141987179184
Author: Marinus Schraal <mschraal gnome org>
Date:   Wed Jan 8 17:11:14 2020 +0100

    Let consumers handle playlists availability
    
    PlaylistsView and MPRIS want to know when playlists become available to
    setup some actions.
    
    For example PlaylistsView by default selects a row for intial display if
    the list is filled. This was previously done by emitting a signal after
    the initial load of playlists. However, in certain  conditions this
    signal could already have fired before the view was even created, so no
    initial row would be selected.
    
    Now PlaylistsView instead directly listen to the playlists model for
    changes and uses an initial state variable to check if it is needed to
    activate a row.
    
    Closes: #348

 gnomemusic/coremodel.py                         |  1 -
 gnomemusic/grilowrappers/grltrackerplaylists.py |  1 -
 gnomemusic/mpris.py                             | 41 ++++++++++---------------
 gnomemusic/views/playlistsview.py               | 27 ++++++++++------
 4 files changed, 34 insertions(+), 36 deletions(-)
---
diff --git a/gnomemusic/coremodel.py b/gnomemusic/coremodel.py
index a8579159..37c8f230 100644
--- a/gnomemusic/coremodel.py
+++ b/gnomemusic/coremodel.py
@@ -68,7 +68,6 @@ class CoreModel(GObject.GObject):
     __gsignals__ = {
         "artists-loaded": (GObject.SignalFlags.RUN_FIRST, None, ()),
         "playlist-loaded": (GObject.SignalFlags.RUN_FIRST, None, (int,)),
-        "playlists-loaded": (GObject.SignalFlags.RUN_FIRST, None, ()),
     }
 
     active_playlist = GObject.Property(type=Playlist, default=None)
diff --git a/gnomemusic/grilowrappers/grltrackerplaylists.py b/gnomemusic/grilowrappers/grltrackerplaylists.py
index acd626a9..546e2852 100644
--- a/gnomemusic/grilowrappers/grltrackerplaylists.py
+++ b/gnomemusic/grilowrappers/grltrackerplaylists.py
@@ -145,7 +145,6 @@ class GrlTrackerPlaylists(GObject.GObject):
             self._window.notifications_popup.pop_loading()
             return
         if not media:
-            self._coremodel.emit("playlists-loaded")
             self._window.notifications_popup.pop_loading()
             return
 
diff --git a/gnomemusic/mpris.py b/gnomemusic/mpris.py
index dc9822a4..60205d07 100644
--- a/gnomemusic/mpris.py
+++ b/gnomemusic/mpris.py
@@ -46,6 +46,7 @@ class DBusInterface:
         :param str path: object path
         """
         self._path = path
+        self._signals = None
         Gio.bus_get(Gio.BusType.SESSION, None, self._bus_get_sync, name)
 
     def _bus_get_sync(self, source, res, name):
@@ -124,6 +125,9 @@ class DBusInterface:
             invocation.return_value(None)
 
     def _dbus_emit_signal(self, signal_name, values):
+        if self._signals is None:
+            return
+
         signal = self._signals[signal_name]
         parameters = []
         for arg_name, arg_signature in signal['args'].items():
@@ -299,8 +303,11 @@ class MPRIS(DBusInterface):
             "playlist-loaded", self._on_player_playlist_changed)
 
         self._playlists_model = self._coremodel.props.playlists_sort
-        self._playlists_loaded_id = self._coremodel.connect(
-            "playlists-loaded", self._on_playlists_loaded)
+        n_items = self._playlists_model.get_n_items()
+        self._on_playlists_items_changed(
+            self._playlists_model, 0, n_items, n_items)
+        self._playlists_model.connect(
+            "items-changed", self._on_playlists_items_changed)
 
         self._player_playlist_type = None
         self._path_list = []
@@ -603,33 +610,19 @@ class MPRIS(DBusInterface):
         self._properties_changed(
             MPRIS.MEDIA_PLAYER2_PLAYLISTS_IFACE, properties, [])
 
-    def _on_playlists_loaded(self, klass):
-        self._coremodel.disconnect(self._playlists_loaded_id)
-        for playlist in self._playlists_model:
-            playlist.connect("notify::title", self._on_playlist_renamed)
-            playlist.connect(
-                "notify::active", self._on_player_playlist_changed)
-
-        self._playlists_model.connect(
-            "items-changed", self._on_playlists_count_changed)
-        self._on_playlists_count_changed(None, None, 0, 0)
-
-    @log
-    def _on_playlists_count_changed(self, model, position, removed, added):
-        playlist_count = self._playlists_model.get_n_items()
-        if playlist_count == self._previous_playlist_count:
-            return
+    def _on_playlists_items_changed(self, model, position, removed, added):
+        if added > 0:
+            for i in list(range(added)):
+                playlist = model[position + i]
+                playlist.connect("notify::title", self._on_playlist_renamed)
+                playlist.connect(
+                    "notify::active", self._on_player_playlist_changed)
 
-        self._previous_playlist_count = playlist_count
+        playlist_count = model.get_n_items()
         properties = {"PlaylistCount": GLib.Variant("u", playlist_count)}
         self._properties_changed(
             MPRIS.MEDIA_PLAYER2_PLAYLISTS_IFACE, properties, [])
 
-        if added == 0:
-            return
-
-        model[position].connect("notify::title", self._on_playlist_renamed)
-
     @log
     def _on_playlist_renamed(self, playlist, param):
         mpris_playlist = self._get_mpris_playlist_from_playlist(playlist)
diff --git a/gnomemusic/views/playlistsview.py b/gnomemusic/views/playlistsview.py
index e7c60755..8bc56b66 100644
--- a/gnomemusic/views/playlistsview.py
+++ b/gnomemusic/views/playlistsview.py
@@ -62,6 +62,8 @@ class PlaylistsView(BaseView):
         self._window = application.props.window
         self._player = player
 
+        self._clean_fill = True
+
         self._song_popover = PlaylistContextMenu(self._view)
 
         play_song = Gio.SimpleAction.new('play_song', None)
@@ -108,11 +110,12 @@ class PlaylistsView(BaseView):
 
         self._sidebar.bind_model(self._model, self._add_playlist_to_sidebar)
 
-        self._loaded_id = self._coremodel.connect(
-            "playlists-loaded", self._on_playlists_loaded)
         self._active_playlist_id = self._coremodel.connect(
             "notify::active-playlist", self._on_active_playlist_changed)
 
+        self._model.connect("items-changed", self._on_playlists_model_changed)
+        self._on_playlists_model_changed(self._model, 0, 0, 0)
+
         # Selection is only possible from the context menu
         self.disconnect(self._selection_mode_id)
 
@@ -147,15 +150,17 @@ class PlaylistsView(BaseView):
         row = PlaylistTile(playlist)
         return row
 
-    def _on_playlists_loaded(self, klass):
-        self._coremodel.disconnect(self._loaded_id)
-        self._model.connect("items-changed", self._on_playlists_model_changed)
-
-        first_row = self._sidebar.get_row_at_index(0)
-        self._sidebar.select_row(first_row)
-        first_row.emit("activate")
-
     def _on_playlists_model_changed(self, model, position, removed, added):
+        if model.get_n_items() == 0:
+            self._clean_fill = True
+            return
+        elif self._clean_fill:
+            first_row = self._sidebar.get_row_at_index(0)
+            self._sidebar.select_row(first_row)
+            first_row.emit("activate")
+            self._clean_fill = True
+            return
+
         if removed == 0:
             return
 
@@ -164,6 +169,7 @@ class PlaylistsView(BaseView):
         if row_next:
             self._sidebar.select_row(row_next)
             row_next.emit("activate")
+            self._clean_fill = True
 
     @log
     def _on_view_right_clicked(self, gesture, n_press, x, y):
@@ -218,6 +224,7 @@ class PlaylistsView(BaseView):
     @log
     def _on_playlist_activated(self, sidebar, row, data=None):
         """Update view with content from selected playlist"""
+        self._clean_fill = False
         playlist = row.props.playlist
 
         if self.rename_active: