Add option to share bookmarks publicly (#503)

* Make shared view public, add user profile fallback

* Allow unauthenticated access to shared bookmarks API

* Link shared bookmarks in unauthenticated layout

* Add public sharing setting

* Only show shared bookmarks link if there are publicly shared bookmarks

* Disable public sharing if sharing is disabled

* Show specific helper text when public sharing is enabled

* Fix tests

* Add more tests

* Improve setting description

bookmarks/context_processors.py

@@ -1,12 +1,25 @@
+from bookmarks import queries
 from bookmarks.models import Toast
 
 
 def toasts(request):
-    user = request.user if hasattr(request, 'user') else None
-    toast_messages = Toast.objects.filter(owner=user, acknowledged=False) if user and user.is_authenticated else []
+    user = request.user
+    toast_messages = Toast.objects.filter(owner=user, acknowledged=False) if user.is_authenticated else []
     has_toasts = len(toast_messages) > 0
 
     return {
         'has_toasts': has_toasts,
         'toast_messages': toast_messages,
     }
+
+
+def public_shares(request):
+    # Only check for public shares for anonymous users
+    if not request.user.is_authenticated:
+        query_set = queries.query_shared_bookmarks(None, request.user_profile, '', True)
+        has_public_shares = query_set.count() > 0
+        return {
+            'has_public_shares': has_public_shares,
+        }
+
+    return {}