[gnome-music/wip/jfelder/tracker-not-found-view: 2/2] app: Display an empty view when tracker cannot be found

[Jean Felder <jfelder src gnome org>]

commit 33b1617d0fb3e75862bb9edd36d557090d8aaf3c
Author: Jean Felder <jfelder src gnome org>
Date:   Wed Jan 30 11:26:44 2019 +0100

    app: Display an empty view when tracker cannot be found
    
    This new empty view is displayed if Tracker is not installed on the
    system.
    
    Closes: #165

 gnomemusic/__init__.py        |  6 ++----
 gnomemusic/grilo.py           |  9 +++++++++
 gnomemusic/views/emptyview.py | 15 ++++++++++++++-
 gnomemusic/window.py          |  4 +++-
 4 files changed, 28 insertions(+), 6 deletions(-)
---
diff --git a/gnomemusic/__init__.py b/gnomemusic/__init__.py
index 6da3044c..1deeccfc 100644
--- a/gnomemusic/__init__.py
+++ b/gnomemusic/__init__.py
@@ -81,14 +81,12 @@ class TrackerWrapper(GObject.GObject):
     """Create a connection to an instance of Tracker"""
 
     def __init__(self):
-        self._tracker = None
         try:
             self._tracker = Tracker.SparqlConnection.get(None)
         except Exception as e:
-            from sys import exit
+            self._tracker = None
             logger.error(
-                "Cannot connect to tracker, error {}\nExiting".format(str(e)))
-            exit(1)
+                "Cannot connect to tracker, error {}\n".format(str(e)))
 
     @GObject.Property(type=object, flags=GObject.ParamFlags.READABLE)
     def tracker(self):
diff --git a/gnomemusic/grilo.py b/gnomemusic/grilo.py
index 5f90e41f..73716d67 100644
--- a/gnomemusic/grilo.py
+++ b/gnomemusic/grilo.py
@@ -506,8 +506,17 @@ class Grilo(GObject.GObject):
 
         # TODO: currently just checks tracker, should work with any
         # queryable supported Grilo source.
+        if not self.props.tracker_available:
+            callback(False)
+            return
+
         self.sparqltracker.query_async(Query.all_songs_count(), None,
                                        songs_query_cb, None)
 
+    @GObject.Property(
+        type=bool, default=False, flags=GObject.ParamFlags.READABLE)
+    def tracker_available(self):
+        return self.sparqltracker is not None
+
 
 grilo = Grilo()
diff --git a/gnomemusic/views/emptyview.py b/gnomemusic/views/emptyview.py
index ff31654d..f44869e0 100644
--- a/gnomemusic/views/emptyview.py
+++ b/gnomemusic/views/emptyview.py
@@ -48,6 +48,7 @@ class EmptyView(Gtk.Stack):
         INITIAL = 0
         EMPTY = 1
         SEARCH = 2
+        NO_TRACKER = 3
 
     __gtype_name__ = "EmptyView"
 
@@ -72,7 +73,7 @@ class EmptyView(Gtk.Stack):
 
         self._state = EmptyView.State.INITIAL
 
-    @GObject.Property(type=int, default=0, minimum=0, maximum=2)
+    @GObject.Property(type=int, default=0, minimum=0, maximum=3)
     def state(self):
         """Get the state of the empty view
 
@@ -94,6 +95,8 @@ class EmptyView(Gtk.Stack):
             self._set_empty_state()
         elif self._state == EmptyView.State.SEARCH:
             self._set_search_state()
+        elif self._state == EmptyView.State.NO_TRACKER:
+            self._set_no_tracker_state()
         self.show_all()
 
     @log
@@ -118,3 +121,13 @@ class EmptyView(Gtk.Stack):
         self._main_label.props.label = _("No music found")
         self._icon.props.margin_bottom = 18
         self._information_label.props.label = _("Try a different search")
+
+    @log
+    def _set_no_tracker_state(self):
+        self._main_label.props.margin_bottom = 12
+        self._main_label.props.label = _(
+            "Unable to find Tracker on your operating system")
+        self._icon.props.margin_bottom = 18
+        self._information_label.props.label = ""
+
+        self._icon.props.icon_name = "dialog-error"
diff --git a/gnomemusic/window.py b/gnomemusic/window.py
index 539642a4..dd20b350 100644
--- a/gnomemusic/window.py
+++ b/gnomemusic/window.py
@@ -201,7 +201,9 @@ class Window(Gtk.ApplicationWindow):
     def _switch_to_empty_view(self):
         did_initial_state = self._settings.get_boolean('did-initial-state')
 
-        if did_initial_state:
+        if not grilo.props.tracker_available:
+            self.views[View.EMPTY].props.state = EmptyView.State.NO_TRACKER
+        elif did_initial_state:
             self.views[View.EMPTY].props.state = EmptyView.State.EMPTY
         else:
             self.views[View.EMPTY].props.state = EmptyView.State.INITIAL