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, 60 insertions, 22 deletions

diff --git a/app/helpers/labels_helper.rb b/app/helpers/labels_helper.rb
index b9f3d6c75c2..221a84b042f 100644
--- a/app/helpers/labels_helper.rb
+++ b/app/helpers/labels_helper.rb
@@ -4,9 +4,8 @@ module LabelsHelper
   # Link to a Label
   #
   # label   - Label object to link to
-  # project - Project object which will be used as the context for the label's
-  #           link. If omitted, defaults to `@project`, or the label's own
-  #           project.
+  # subject - Project/Group object which will be used as the context for the
+  #           label's link. If omitted, defaults to the label's own group/project.
   # type    - The type of item the link will point to (:issue or
   #           :merge_request). If omitted, defaults to :issue.
   # block   - An optional block that will be passed to `link_to`, forming the
@@ -15,15 +14,14 @@ module LabelsHelper
   #
   # Examples:
   #
-  #   # Allow the generated link to use the label's own project
+  #   # Allow the generated link to use the label's own subject
   #   link_to_label(label)
   #
-  #   # Force the generated link to use @project
-  #   @project = Project.first
-  #   link_to_label(label)
+  #   # Force the generated link to use a provided group
+  #   link_to_label(label, subject: Group.last)
   #
   #   # Force the generated link to use a provided project
-  #   link_to_label(label, project: Project.last)
+  #   link_to_label(label, subject: Project.last)
   #
   #   # Force the generated link to point to merge requests instead of issues
   #   link_to_label(label, type: :merge_request)
@@ -32,9 +30,8 @@ module LabelsHelper
   #   link_to_label(label) { "My Custom Label Text" }
   #
   # Returns a String
-  def link_to_label(label, project: nil, type: :issue, tooltip: true, css_class: nil, &block)
-    project ||= @project || label.project
-    link = label_filter_path(project, label, type: type)
+  def link_to_label(label, subject: nil, type: :issue, tooltip: true, css_class: nil, &block)
+    link = label_filter_path(subject || label.subject, label, type: type)
 
     if block_given?
       link_to link, class: css_class, &block
@@ -43,15 +40,40 @@ module LabelsHelper
     end
   end
 
-  def label_filter_path(project, label, type: issue)
-    send("namespace_project_#{type.to_s.pluralize}_path",
-                project.namespace,
-                project,
-                label_name: [label.name])
+  def label_filter_path(subject, label, type: :issue)
+    case subject
+    when Group
+      send("#{type.to_s.pluralize}_group_path",
+                  subject,
+                  label_name: [label.name])
+    when Project
+      send("namespace_project_#{type.to_s.pluralize}_path",
+                  subject.namespace,
+                  subject,
+                  label_name: [label.name])
+    end
+  end
+
+  def edit_label_path(label)
+    case label
+    when GroupLabel then edit_group_label_path(label.group, label)
+    when ProjectLabel then edit_namespace_project_label_path(label.project.namespace, label.project, label)
+    end
+  end
+
+  def destroy_label_path(label)
+    case label
+    when GroupLabel then group_label_path(label.group, label)
+    when ProjectLabel then namespace_project_label_path(label.project.namespace, label.project, label)
+    end
   end
 
-  def project_label_names
-    @project.labels.pluck(:title)
+  def toggle_subscription_data(label)
+    return unless label.is_a?(ProjectLabel)
+
+    {
+      url: toggle_subscription_namespace_project_label_path(label.project.namespace, label.project, label)
+    }
   end
 
   def render_colored_label(label, label_suffix = '', tooltip: true)
@@ -68,8 +90,8 @@ module LabelsHelper
     span.html_safe
   end
 
-  def render_colored_cross_project_label(label, tooltip: true)
-    label_suffix = label.project.name_with_namespace
+  def render_colored_cross_project_label(label, source_project = nil, tooltip: true)
+    label_suffix = source_project ? source_project.name_with_namespace : label.project.name_with_namespace
     label_suffix = " <i>in #{escape_once(label_suffix)}</i>"
     render_colored_label(label, label_suffix, tooltip: tooltip)
   end
@@ -115,7 +137,10 @@ module LabelsHelper
   end
 
   def labels_filter_path
+    return group_labels_path(@group, :json) if @group
+
     project = @target_project || @project
+
     if project
       namespace_project_labels_path(project.namespace, project, :json)
     else
@@ -124,11 +149,24 @@ module LabelsHelper
   end
 
   def label_subscription_status(label)
-    label.subscribed?(current_user) ? 'subscribed' : 'unsubscribed'
+    case label
+    when GroupLabel then 'Subscribing to group labels is currently not supported.'
+    when ProjectLabel then label.subscribed?(current_user) ? 'subscribed' : 'unsubscribed'
+    end
   end
 
   def label_subscription_toggle_button_text(label)
-    label.subscribed?(current_user) ? 'Unsubscribe' : 'Subscribe'
+    case label
+    when GroupLabel then 'Subscribing to group labels is currently not supported.'
+    when ProjectLabel then label.subscribed?(current_user) ? 'Unsubscribe' : 'Subscribe'
+    end
+  end
+
+  def label_deletion_confirm_text(label)
+    case label
+    when GroupLabel then 'Remove this label? This will affect all projects within the group. Are you sure?'
+    when ProjectLabel then 'Remove this label? Are you sure?'
+    end
   end
 
   # Required for Banzai::Filter::LabelReferenceFilter