views: Link to apps-add page from a tag click in app page

Tests:

- On Coturn app page, clicking on a tag redirects to Add New App page with tag
filter set to clicked tag.

- On Names app page, clicking on a tag redirects to system page with tag filter
set to clicked tag.

- On Operations page such as when installing an app, clicking on a tag redirects
to Add New App page with tag filter set to clicked tag.

- On Index page such when OpenVPN is clicked description for OpenVPN is shown.
Clicking on a tag in the description redirects to Add New App page with tag
filter set to clicked tag.

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

plinth/templates/app-header.html

@@ -47,7 +47,7 @@
       <div class="app-tags d-flex align-items-center flex-wrap">
         {% for tag in app_info.tags %}
           {% if not forloop.first %}•{% endif %}
-          <a href="{{ active_section_url }}?tag={{ tag|urlencode }}"
+          <a href="{% if tag_search_url %}{% url tag_search_url %}?tag={{ tag|urlencode }}{% endif %}"
              class="btn btn-default rounded-pill tag">
             {% trans tag %}
           </a>

plinth/views.py

@@ -174,12 +174,16 @@ def index(request):
         shortcut for shortcut in shortcuts if shortcut.component_id == selected
     ]
     selected_shortcut = selected_shortcut[0] if selected_shortcut else None
+    tag_search_url = None
+    if selected_shortcut:
+        tag_search_url = _get_tag_search_url(selected_shortcut.app)
 
     return TemplateResponse(
         request, 'index.html', {
             'title': _('FreedomBox'),
             'shortcuts': shortcuts,
             'selected_shortcut': selected_shortcut,
+            'tag_search_url': tag_search_url,
         })
 
 
@@ -266,6 +270,34 @@ def _get_all_tags(menu_items: list[menu.Menu]) -> list[str]:
     return sorted(get_tags(menu_items), key=_)
 
 
+def _get_tag_search_url(app: app_module.App) -> str:
+    """Return the URL to which clicking on tags to redirect to."""
+    default_url = 'apps-add'
+
+    menus = list(app.get_components_of_type(menu.Menu))
+    if not menus:
+        return default_url  # When app has no menu item.
+
+    parent_section = menus[0]
+    for _index in range(10):
+        if parent_section.parent_url_name in ('index', None):
+            break
+
+        try:
+            parent_section = menu.Menu.get_with_url_name(
+                parent_section.parent_url_name)
+        except LookupError:
+            return default_url
+    else:
+        # There was a loop in traversing to the parent menu item.
+        return default_url
+
+    if parent_section.url_name == 'apps':
+        return default_url
+
+    return parent_section.url_name
+
+
 class AppsView(TemplateView):
     """View for showing installed apps.
 
@@ -507,6 +539,7 @@ class AppView(FormView):
         context['firewall'] = self.app.get_components_of_type(Firewall)
 
         context['has_backup_restore'] = _has_backup_restore(self.app)
+        context['tag_search_url'] = _get_tag_search_url(self.app)
 
         return context
 
@@ -532,6 +565,7 @@ class AppOperationsView(TemplateView):
         context['operations'] = operation.manager.filter(self.app.app_id)
         # Refresh periodically while operations are running
         context['refresh_page_sec'] = 3 if context['operations'] else 0
+        context['tag_search_url'] = _get_tag_search_url(self.app)
 
         return context
 
@@ -569,6 +603,8 @@ class SetupView(TemplateView):
         elif context['setup_state'] == app_module.App.SetupState.UP_TO_DATE:
             context['refresh_page_sec'] = 0
 
+        context['tag_search_url'] = _get_tag_search_url(app)
+
         return context
 
     def dispatch(self, request, *args, **kwargs):