[gnome-music] Update songs when they are being added or deleted.

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit 5d16c7b03b3e09a83161fede26b1d6d010025e85
Author: Sai Suman Prayaga <suman sai14 gmail com>
Date:   Fri Mar 7 03:38:46 2014 +0530

    Update songs when they are being added or deleted.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=700726

 gnomemusic/grilo.py   |   29 +++++++++++++++++++-
 gnomemusic/toolbar.py |    8 +++++-
 gnomemusic/view.py    |   26 +++++++++++++++++
 gnomemusic/window.py  |   72 +++++++++++++++++++++++++++++++++++-------------
 4 files changed, 113 insertions(+), 22 deletions(-)
---
diff --git a/gnomemusic/grilo.py b/gnomemusic/grilo.py
index cf852ac..b93b00f 100644
--- a/gnomemusic/grilo.py
+++ b/gnomemusic/grilo.py
@@ -34,7 +34,8 @@ from gnomemusic.query import Query
 class Grilo(GObject.GObject):
 
     __gsignals__ = {
-        'ready': (GObject.SIGNAL_RUN_FIRST, None, ())
+        'ready': (GObject.SIGNAL_RUN_FIRST, None, ()),
+        'changes-pending': (GObject.SIGNAL_RUN_FIRST, None, ())
     }
 
     METADATA_KEYS = [
@@ -48,6 +49,9 @@ class Grilo(GObject.GObject):
         Grl.METADATA_KEY_THUMBNAIL,
     ]
 
+    CHANGED_MEDIA_MAX_ITEMS = 500
+    CHANGED_MEDIA_SIGNAL_TIMEOUT = 2000
+
     def __init__(self):
         GObject.GObject.__init__(self)
         self.playlist_path = GLib.build_filenamev([GLib.get_user_data_dir(),
@@ -60,6 +64,8 @@ class Grilo(GObject.GObject):
 
         self.sources = {}
         self.tracker = None
+        self.changed_media_ids = []
+        self.pending_event_id = 0
 
         self.registry = Grl.Registry.get_default()
         self.registry.connect('source_added', self._on_source_added)
@@ -69,6 +75,25 @@ class Grilo(GObject.GObject):
             self.registry.load_all_plugins()
         except GLib.GError:
             print('Failed to load plugins.')
+        if self.tracker is not None:
+            print("tracker is not none")
+
+    def _on_content_changed(self, mediaSource, changedMedias, changeType, locationUnknown):
+        if changeType == Grl.SourceChangeType.ADDED or changeType == Grl.SourceChangeType.REMOVED:
+            self.changed_media_ids.append(changedMedias[0].get_id())
+            if len(self.changed_media_ids) >= self.CHANGED_MEDIA_MAX_ITEMS:
+                self.emit_change_signal()
+            else:
+                if self.pending_event_id > 0:
+                    GLib.Source.remove(self.pending_event_id)
+                    self.pending_event_id = 0
+                self.pending_event_id = GLib.timeout_add(self.CHANGED_MEDIA_SIGNAL_TIMEOUT, 
self.emit_change_signal)
+
+    def emit_change_signal(self):
+        self.changed_media_ids = []
+        self.pending_event_id = 0
+        self.emit('changes-pending')
+        return False
 
     def _on_source_added(self, pluginRegistry, mediaSource):
         id = mediaSource.get_id()
@@ -83,6 +108,8 @@ class Grilo(GObject.GObject):
 
                 if self.tracker is not None:
                     self.emit('ready')
+                    self.tracker.notify_change_start()
+                    self.tracker.connect('content-changed', self._on_content_changed)
 
     def _on_source_removed(self, pluginRegistry, mediaSource):
         print('source removed')
diff --git a/gnomemusic/toolbar.py b/gnomemusic/toolbar.py
index 2890ae5..09d9541 100644
--- a/gnomemusic/toolbar.py
+++ b/gnomemusic/toolbar.py
@@ -56,7 +56,7 @@ class Toolbar(GObject.GObject):
 
     def __init__(self):
         GObject.GObject.__init__(self)
-        self._stack_switcher = StackSwitcher(margin_top=2, margin_bottom=2)
+        self._stack_switcher = StackSwitcher(margin_top=2, margin_bottom=2, can_focus=False)
         self._stack_switcher.show()
         self._ui = Gtk.Builder()
         self._ui.add_from_resource('/org/gnome/Music/headerbar.ui')
@@ -119,6 +119,12 @@ class Toolbar(GObject.GObject):
     def get_stack(self):
         return self._stack_switcher.get_stack()
 
+    def hide_stack(self):
+        self._stack_switcher.hide()
+
+    def show_stack(self):
+        self._stack_switcher.show()
+
     def set_selection_mode(self, selectionMode):
         self._selectionMode = selectionMode
         if selectionMode:
diff --git a/gnomemusic/view.py b/gnomemusic/view.py
index b52a403..b969b36 100644
--- a/gnomemusic/view.py
+++ b/gnomemusic/view.py
@@ -149,6 +149,10 @@ class ViewContainer(Stack):
                           self._on_view_selection_changed)
 
         self._discovering_urls = {}
+        grilo.connect('changes-pending', self._on_changes_pending)
+
+    def _on_changes_pending(self, data=None):
+        pass
 
     def _get_remaining_item_count(self):
         if self._cached_count < 0:
@@ -333,6 +337,13 @@ class Albums(ViewContainer):
         self.items_selected = []
         self.items_selected_callback = None
 
+    def _on_changes_pending(self, data=None):
+        if (self._init):
+            self._offset = 0
+            self._cached_count = -1
+            self._model.clear()
+            self.populate()
+
     def _back_button_clicked(self, widget, data=None):
         self.set_visible_child(self._grid)
 
@@ -406,6 +417,13 @@ class Songs(ViewContainer):
         self.player = player
         self.player.connect('playlist-item-changed', self.update_model)
 
+    def _on_changes_pending(self, data=None):
+        if (self._init):
+            self._model.clear()
+            self._offset = 0
+            self._cached_count = -1
+            self.populate()
+
     def _on_item_activated(self, widget, id, path):
         _iter = self.filter.get_iter(path)
         child_iter = self.filter.convert_iter_to_child_iter(_iter)
@@ -579,6 +597,14 @@ class Artists (ViewContainer):
                 add_class('artist-panel-white')
         self.show_all()
 
+    def _on_changes_pending(self, data=None):
+        if (self._init):
+            self._model.clear()
+            self._artists.clear()
+            self._offset = 0
+            self._cached_count = -1
+            self._populate()
+
     def _populate(self, data=None):
         selection = self.view.get_generic_view().get_selection()
         if not selection.get_selected()[1]:
diff --git a/gnomemusic/window.py b/gnomemusic/window.py
index 194d64d..d433332 100644
--- a/gnomemusic/window.py
+++ b/gnomemusic/window.py
@@ -39,6 +39,7 @@ from gnomemusic.query import Query
 import gnomemusic.view as Views
 import gnomemusic.widgets as Widgets
 from gnomemusic.playlists import Playlists
+from gnomemusic.grilo import grilo
 
 playlist = Playlists.get_default()
 tracker = Tracker.SparqlConnection.get(None)
@@ -95,6 +96,31 @@ class Window(Gtk.ApplicationWindow):
         except GLib.GError:
             # We cannot grab media keys if no settings daemon is running
             pass
+        grilo.connect('changes-pending', self._on_changes_pending)
+
+    def _on_changes_pending(self, data=None):
+        count = 1
+        cursor = tracker.query(Query.SONGS_COUNT, None)
+        if cursor is not None and cursor.next(None):
+            count = cursor.get_integer(0)
+        if not count > 0:
+            print("switching to Empty view")
+            self._stack.disconnect(self._on_notify_model_id)
+            self.disconnect(self._key_press_event_id)
+            for i in range(0, 4):
+                view = self.views.pop()
+                view.destroy()
+            self.toolbar.hide_stack()
+            self._switch_to_empty_view()
+        else:
+            if (self.views[0] == self.views[-1]):
+                print("switching to player view")
+                view = self.views.pop()
+                view.destroy()
+                self._switch_to_player_view()
+                self.toolbar._search_button.set_sensitive(True)
+                self.toolbar._select_button.set_sensitive(True)
+                self.toolbar.show_stack()
 
     def _on_configure_event(self, widget, event):
         size = widget.get_size()
@@ -160,28 +186,10 @@ class Window(Gtk.ApplicationWindow):
         if cursor is not None and cursor.next(None):
             count = cursor.get_integer(0)
         if count > 0:
-            self.views.append(Views.Albums(self.toolbar, self.selection_toolbar, self.player))
-            self.views.append(Views.Artists(self.toolbar, self.selection_toolbar, self.player))
-            self.views.append(Views.Songs(self.toolbar, self.selection_toolbar, self.player))
-            self.views.append(Views.Playlist(self.toolbar, self.selection_toolbar, self.player))
-
-            for i in self.views:
-                self._stack.add_titled(i, i.title, i.title)
-
-            self.toolbar.set_stack(self._stack)
-            self.toolbar.searchbar.show()
-
-            self._on_notify_model_id = self._stack.connect('notify::visible-child', self._on_notify_mode)
-            self.connect('destroy', self._notify_mode_disconnect)
-            self.connect('key_press_event', self._on_key_press)
-
-            self.views[0].populate()
+            self._switch_to_player_view()
         #To revert to the No Music View when no songs are found
         else:
-            self.views.append(Views.Empty(self.toolbar, self.player))
-            self._stack.add_titled(self.views[0], _("Empty"), _("Empty"))
-            self.toolbar._search_button.set_sensitive(False)
-            self.toolbar._select_button.set_sensitive(False)
+            self._switch_to_empty_view()
 
         self.toolbar._search_button.connect('toggled', self._on_search_toggled)
         self.toolbar.connect('selection-mode-changed', self._on_selection_mode_changed)
@@ -196,6 +204,30 @@ class Window(Gtk.ApplicationWindow):
         self._box.show()
         self.show()
 
+    def _switch_to_empty_view(self):
+        self.views.append(Views.Empty(self.toolbar, self.player))
+        self._stack.add_titled(self.views[0], _("Empty"), _("Empty"))
+        self.toolbar._search_button.set_sensitive(False)
+        self.toolbar._select_button.set_sensitive(False)
+
+    def _switch_to_player_view(self):
+        self.views.append(Views.Albums(self.toolbar, self.selection_toolbar, self.player))
+        self.views.append(Views.Artists(self.toolbar, self.selection_toolbar, self.player))
+        self.views.append(Views.Songs(self.toolbar, self.selection_toolbar, self.player))
+        self.views.append(Views.Playlist(self.toolbar, self.selection_toolbar, self.player))
+
+        for i in self.views:
+            self._stack.add_titled(i, i.title, i.title)
+
+        self.toolbar.set_stack(self._stack)
+        self.toolbar.searchbar.show()
+
+        self._on_notify_model_id = self._stack.connect('notify::visible-child', self._on_notify_mode)
+        self.connect('destroy', self._notify_mode_disconnect)
+        self._key_press_event_id = self.connect('key_press_event', self._on_key_press)
+
+        self.views[0].populate()
+
     def _on_select_all(self, action, param):
         if self.toolbar._state != ToolbarState.SINGLE:
             model = self._stack.get_visible_child()._model