Refactor `UserReferenceFilter#user_link_filter`

lib/gitlab/markdown/user_reference_filter.rb

@@ -38,57 +38,65 @@ module Gitlab
       # Returns a String with `@user` references replaced with links. All links
       # have `gfm` and `gfm-project_member` class names attached for styling.
       def user_link_filter(text)
-        project = context[:project]
+        self.class.references_in(text) do |match, username|
+          if username == 'all'
+            link_to_all
+          elsif namespace = Namespace.find_by(path: username)
+            link_to_namespace(namespace) || match
+          else
+            match
+          end
+        end
+      end
+
+      private
+
+      def urls
+        Rails.application.routes.url_helpers
+      end
 
-        self.class.references_in(text) do |match, user|
-          klass = reference_class(:project_member)
+      def link_class
+        reference_class(:project_member)
+      end
+
+      def link_to_all
+        project = context[:project]
 
-          if user == 'all'
         # FIXME (rspeicher): Law of Demeter
         push_result(:user, *project.team.members.flatten)
 
-            url = link_to_all(project)
-
-            %(<a href="#{url}" class="#{klass}">@#{user}</a>)
-          elsif namespace = Namespace.find_by(path: user)
-            if namespace.is_a?(Group)
-              if user_can_reference_group?(namespace)
-                push_result(:user, *namespace.users)
+        url = urls.namespace_project_url(project.namespace, project,
+                                         only_path: context[:only_path])
 
-                url = group_url(user, only_path: context[:only_path])
-                %(<a href="#{url}" class="#{klass}">@#{user}</a>)
-              else
-                match
+        %(<a href="#{url}" class="#{link_class}">@all</a>)
       end
-            else
-              push_result(:user, namespace.owner)
 
-              url = user_url(user, only_path: context[:only_path])
-              %(<a href="#{url}" class="#{klass}">@#{user}</a>)
-            end
+      def link_to_namespace(namespace)
+        if namespace.is_a?(Group)
+          link_to_group(namespace.path, namespace)
         else
-            match
-          end
+          link_to_user(namespace.path, namespace)
         end
       end
 
-      private
+      def link_to_group(group, namespace)
+        if user_can_reference_group?(namespace)
+          push_result(:user, *namespace.users)
 
-      def urls
-        Rails.application.routes.url_helpers
-      end
+          url = urls.group_url(group, only_path: context[:only_path])
 
-      def group_url(*args)
-        urls.group_url(*args)
+          %(<a href="#{url}" class="#{link_class}">@#{group}</a>)
+        else
+          nil
         end
-
-      def user_url(*args)
-        urls.user_url(*args)
       end
 
-      def link_to_all(project)
-        urls.namespace_project_url(project.namespace, project,
-                                   only_path: context[:only_path])
+      def link_to_user(user, namespace)
+        push_result(:user, namespace.owner)
+
+        url = urls.user_url(user, only_path: context[:only_path])
+
+        %(<a href="#{url}" class="#{link_class}">@#{user}</a>)
       end
 
       def user_can_reference_group?(group)