power: Use AppView for app page

Tests:

- Enable/disable button is not shown.

- Diagnostics menu item is not shown.

- If apt is busy a warning message is shown.

- Restart and Shutdown buttons are shown and work.

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

plinth/modules/power/__init__.py

@@ -21,6 +21,8 @@ class PowerApp(app_module.App):
 
     _version = 1
 
+    can_be_disabled = False
+
     def __init__(self):
         """Create components for the app."""
         super().__init__()

plinth/modules/power/urls.py

@@ -8,7 +8,7 @@ from django.urls import re_path
 from . import views
 
 urlpatterns = [
-    re_path(r'^sys/power/$', views.index, name='index'),
+    re_path(r'^sys/power/$', views.PowerAppView.as_view(), name='index'),
     re_path(r'^sys/power/restart$', views.restart, name='restart'),
     re_path(r'^sys/power/shutdown$', views.shutdown, name='shutdown'),
 ]

plinth/modules/power/views.py

@@ -11,17 +11,20 @@ from django.urls import reverse
 from plinth import actions
 from plinth import app as app_module
 from plinth import package
+from plinth.views import AppView
 
 
-def index(request):
-    """Serve power controls page."""
-    app = app_module.App.get('power')
-    return TemplateResponse(
-        request, 'power.html', {
-            'title': app.info.name,
-            'app_info': app.info,
-            'pkg_manager_is_busy': package.is_package_manager_busy()
-        })
+class PowerAppView(AppView):
+    """Show power app main page."""
+
+    app_id = 'power'
+    template_name = 'power.html'
+
+    def get_context_data(self, *args, **kwargs):
+        """Add additional context data for template."""
+        context = super().get_context_data(*args, **kwargs)
+        context['pkg_manager_is_busy'] = package.is_package_manager_busy()
+        return context
 
 
 def restart(request):