Merge branch 'feature/group-level-labels' into 'master'

Add group level labels

## What does this MR do?

Add group level labels.

## Are there points in the code the reviewer needs to double check?

* `LabelsFinder`
* `Gitlab::Gfm::ReferenceRewriter`
* `Banzai::Filter::LabelReferenceFilter`

## Why was this MR needed?

We'll be adding more feature that allow you to do cross-project management of issues.

## Screenshots (if relevant)

* Group Labels
    ![Group Labels](/uploads/2244c06ad68eae4fb246fb4c81bf8060/2.png)

* Project Labels
    ![Project Labels](/uploads/c5839516d2282b51f7418d9dadbeceb4/1.png)

* Expanded references for group labels when moving issue to another project
    ![Expanded references for group labels when moving issue to another project](/uploads/0c9ab248a8420d4978d59349ae3d42e5/3.png)

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [x] API support added
- Tests
  - [x] Added for this feature/bug
  - [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [ ] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

#19997

See merge request !6425

1 files changed, 46 insertions, 5 deletions

diff --git a/lib/banzai/filter/label_reference_filter.rb b/lib/banzai/filter/label_reference_filter.rb
index 8f262ef3d8d..c24831e68ee 100644
--- a/lib/banzai/filter/label_reference_filter.rb
+++ b/lib/banzai/filter/label_reference_filter.rb
@@ -9,7 +9,7 @@ module Banzai
       end
 
       def find_object(project, id)
-        project.labels.find(id)
+        find_labels(project).find(id)
       end
 
       def self.references_in(text, pattern = Label.reference_pattern)
@@ -35,7 +35,11 @@ module Banzai
         return unless project
 
         label_params = label_params(label_id, label_name)
-        project.labels.find_by(label_params)
+        find_labels(project).find_by(label_params)
+      end
+
+      def find_labels(project)
+        LabelsFinder.new(nil, project_id: project.id).execute(authorized_only: false)
       end
 
       # Parameters to pass to `Label.find_by` based on the given arguments
@@ -60,13 +64,50 @@ module Banzai
       end
 
       def object_link_text(object, matches)
-        if context[:project] == object.project
-          LabelsHelper.render_colored_label(object)
+        if same_group?(object) && namespace_match?(matches)
+          render_same_project_label(object)
+        elsif same_project?(object)
+          render_same_project_label(object)
         else
-          LabelsHelper.render_colored_cross_project_label(object)
+          render_cross_project_label(object, matches)
         end
       end
 
+      def same_group?(object)
+        object.is_a?(GroupLabel) && object.group == project.group
+      end
+
+      def namespace_match?(matches)
+        matches[:project].blank? || matches[:project] == project.path_with_namespace
+      end
+
+      def same_project?(object)
+        object.is_a?(ProjectLabel) && object.project == project
+      end
+
+      def user
+        context[:current_user] || context[:author]
+      end
+
+      def project
+        context[:project]
+      end
+
+      def render_same_project_label(object)
+        LabelsHelper.render_colored_label(object)
+      end
+
+      def render_cross_project_label(object, matches)
+        source_project =
+          if matches[:project]
+            Project.find_with_namespace(matches[:project])
+          else
+            object.project
+          end
+
+        LabelsHelper.render_colored_cross_project_label(object, source_project)
+      end
+
       def unescape_html_entities(text)
         CGI.unescapeHTML(text.to_s)
       end