views: Implement retrieving breadcrumbs of a page

Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Veiko Aasa <veiko17@disroot.org>

plinth/tests/data/urls.py

@@ -3,13 +3,20 @@
 Django URL patterns for running tests.
 """
 
-from django.urls import re_path
+from django.urls import include, re_path
 from django.views.generic import TemplateView
 
 _test_view = TemplateView.as_view(template_name='index.html')
+
+app_urls = [
+    re_path(r'^apps/testapp/$', _test_view, name='index'),
+    re_path(r'^apps/testapp/create/$', _test_view, name='create'),
+]
+
 urlpatterns = [
     re_path(r'^$', _test_view, name='index'),
     re_path(r'^apps/$', _test_view, name='apps'),
+    re_path(r'', include((app_urls, 'testapp'))),
     re_path(r'^sys/$', _test_view, name='system'),
     re_path(r'^test/(?P<a>\d+)/(?P<b>\d+)/(?P<c>\d+)/$', _test_view,
             name='test'),

plinth/tests/test_views.py

@@ -4,8 +4,69 @@ Tests for common FreedomBox views.
 """
 
 import pytest
+from django.urls import resolve
 
-from plinth.views import is_safe_url
+from plinth import menu as menu_module
+from plinth.views import get_breadcrumbs, is_safe_url
+
+
+@pytest.fixture(name='menu')
+def fixture_menu():
+    """Initialized menu module."""
+    menu_module.Menu._all_menus = set()
+    menu_module.init()
+    menu_module.Menu('home-id', name='Home', url_name='index')
+    menu_module.Menu('apps-id', name='Apps', url_name='apps',
+                     parent_url_name='index')
+    menu_module.Menu('testapp-id', name='Test App', url_name='testapp:index',
+                     parent_url_name='apps')
+
+
+def test_get_breadcrumbs(rf, menu):
+    """Test that computing breadcrumbs works."""
+
+    def _crumb(name: str, is_active: bool = False, url_name: str | None = None,
+               is_active_section: bool = False):
+        crumb = {'name': name, 'is_active': is_active, 'url_name': url_name}
+        if is_active_section:
+            crumb['is_active_section'] = True
+
+        return crumb
+
+    def _get(path: str):
+        request = rf.get(path)
+        request.resolver_match = resolve(path)
+        return get_breadcrumbs(request)
+
+    def _compare(dict1: dict[str, dict[str, str | bool]],
+                 dict2: dict[str, dict[str, str | bool]]):
+        """Compare dictionaries with order."""
+        assert list(dict1.items()) == list(dict2.items())
+
+    _compare(_get('/'), {'/': _crumb('Home', True, 'index', True)})
+    _compare(
+        _get('/apps/'), {
+            '/apps/': _crumb('Apps', True, 'apps', True),
+            '/': _crumb('Home', False, 'index'),
+        })
+    _compare(
+        _get('/apps/testapp/'), {
+            '/apps/testapp/': _crumb('Test App', True, 'testapp:index'),
+            '/apps/': _crumb('Apps', False, 'apps', True),
+            '/': _crumb('Home', False, 'index'),
+        })
+    _compare(
+        _get('/apps/testapp/create/'), {
+            '/apps/testapp/create/': _crumb('Here', True, 'testapp:create'),
+            '/apps/testapp/': _crumb('Test App', False, 'testapp:index'),
+            '/apps/': _crumb('Apps', False, 'apps', True),
+            '/': _crumb('Home', False, 'index'),
+        })
+    _compare(
+        _get('/test/1/2/3/'), {
+            '/test/1/2/3/': _crumb('Here', True, 'test', True),
+            '/': _crumb('Home', False, 'index'),
+        })
 
 
 @pytest.mark.parametrize('url', [

plinth/views.py

@@ -11,7 +11,8 @@ import urllib.parse
 from django.contrib import messages
 from django.core.exceptions import ImproperlyConfigured
 from django.forms import Form
-from django.http import Http404, HttpResponseBadRequest, HttpResponseRedirect
+from django.http import (Http404, HttpRequest, HttpResponseBadRequest,
+                         HttpResponseRedirect)
 from django.shortcuts import redirect
 from django.template.response import TemplateResponse
 from django.urls import reverse
@@ -62,6 +63,53 @@ def is_safe_url(url):
     return True
 
 
+def get_breadcrumbs(request: HttpRequest) -> dict[str, dict[str, str | bool]]:
+    """Return all the URL ancestors that can be show as breadcrumbs."""
+    breadcrumbs = {}
+
+    def _add(url: str, name: str, url_name: str | None = None):
+        """Add item into the breadcrumb dictionary."""
+        breadcrumbs[url] = {
+            'name': name,
+            'is_active': request.path == url,
+            'url_name': url_name
+        }
+
+    url_name = request.resolver_match.url_name
+    full_url_name = ':'.join(request.resolver_match.app_names + [url_name])
+    try:
+        menu_item = menu.Menu.get_with_url_name(full_url_name)
+    except LookupError:
+        # There is no menu entry for this page, find it's app.
+        _add(request.path, _('Here'), full_url_name)
+        app_url_name = ':'.join(request.resolver_match.app_names + ['index'])
+        try:
+            menu_item = menu.Menu.get_with_url_name(app_url_name)
+        except LookupError:
+            # Don't know which app this page belongs to, assume parent is Home.
+            menu_item = menu.Menu.get_with_url_name('index')
+
+    for _number in range(10):
+        _add(menu_item.url, menu_item.name, menu_item.url_name)
+        if not menu_item.parent_url_name:
+            # We have reached the top
+            break
+
+        menu_item = menu.Menu.get_with_url_name(menu_item.parent_url_name)
+    else:
+        # Too much hierarchy, we must be in a recursive loop.
+        breadcrumbs = {}
+        menu_item = menu.Menu.get_with_url_name('index')
+        _add(menu_item.url, menu_item.name, menu_item.url_name)
+
+    # Find the active section: 'index', 'apps', 'system' or 'help'.
+    active_section_index = -2 if len(breadcrumbs) >= 2 else -1
+    active_section_key = list(breadcrumbs.keys())[active_section_index]
+    breadcrumbs[active_section_key]['is_active_section'] = True
+
+    return breadcrumbs
+
+
 def messages_error(request, message, exception):
     """Show an error message using Django messages framework.