add inbox view

app/routes/threads.py

@@ -148,15 +148,19 @@ def unsubscribe(thread_id):
 
     user = get_active_user()
     last_post_id = request.form.get('last_post_id', None)
-    if last_post_id is None:
+
+    return_to = request.form.get('return_to', None)
+    if return_to is None and last_post_id is None:
         abort(400)
+    elif return_to is None and last_post_id is not None:
+        return_to = url_for('.thread_by_id', thread_id=thread_id, after=last_post_id)
 
     subscription = Subscriptions.find({'user_id': user.id, 'thread_id': thread_id})
     if not subscription:
-        return redirect(url_for('.thread_by_id', thread_id=thread_id, after=last_post_id))
+        return redirect(return_to)
 
     subscription.delete()
-    return redirect(url_for('.thread_by_id', thread_id=thread_id, after=last_post_id))
+    return redirect(return_to)
 
 @bp.get('/<int:thread_id>/feed.atom/')
 def feed(thread_id):