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

16 files changed, 160 insertions, 81 deletions

diff --git a/lib/api/boards.rb b/lib/api/boards.rb
index b14dd4f6e83..4ac491edc1b 100644
--- a/lib/api/boards.rb
+++ b/lib/api/boards.rb
@@ -65,8 +65,8 @@ module API
           requires :label_id, type: Integer, desc: 'The ID of an existing label'
         end
         post '/lists' do
-          unless user_project.labels.exists?(params[:label_id])
-            render_api_error!({ error: "Label not found!" }, 400)
+          unless available_labels.exists?(params[:label_id])
+            render_api_error!({ error: 'Label not found!' }, 400)
           end
 
           authorize!(:admin_list, user_project)
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 67473f300c9..45120898b76 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -71,6 +71,10 @@ module API
       @project ||= find_project(params[:id])
     end
 
+    def available_labels
+      @available_labels ||= LabelsFinder.new(current_user, project_id: user_project.id).execute
+    end
+
     def find_project(id)
       project = Project.find_with_namespace(id) || Project.find_by(id: id)
 
@@ -118,7 +122,7 @@ module API
     end
 
     def find_project_label(id)
-      label = user_project.labels.find_by_id(id) || user_project.labels.find_by_title(id)
+      label = available_labels.find_by_id(id) || available_labels.find_by_title(id)
       label || not_found!('Label')
     end
 
@@ -197,16 +201,11 @@ module API
     def validate_label_params(params)
       errors = {}
 
-      if params[:labels].present?
-        params[:labels].split(',').each do |label_name|
-          label = user_project.labels.create_with(
-            color: Label::DEFAULT_COLOR).find_or_initialize_by(
-              title: label_name.strip)
+      params[:labels].to_s.split(',').each do |label_name|
+        label = available_labels.find_or_initialize_by(title: label_name.strip)
+        next if label.valid?
 
-          if label.invalid?
-            errors[label.title] = label.errors
-          end
-        end
+        errors[label.title] = label.errors
       end
 
       errors
diff --git a/lib/api/labels.rb b/lib/api/labels.rb
index c806829d69e..642e6345b9e 100644
--- a/lib/api/labels.rb
+++ b/lib/api/labels.rb
@@ -11,7 +11,7 @@ module API
       # Example Request:
       #   GET /projects/:id/labels
       get ':id/labels' do
-        present user_project.labels, with: Entities::Label, current_user: current_user
+        present available_labels, with: Entities::Label, current_user: current_user
       end
 
       # Creates a new label
diff --git a/lib/api/merge_requests.rb b/lib/api/merge_requests.rb
index 2b685621da9..bf8504e1101 100644
--- a/lib/api/merge_requests.rb
+++ b/lib/api/merge_requests.rb
@@ -86,14 +86,11 @@ module API
           render_api_error!({ labels: errors }, 400)
         end
 
+        attrs[:labels] = params[:labels] if params[:labels]
+
         merge_request = ::MergeRequests::CreateService.new(user_project, current_user, attrs).execute
 
         if merge_request.valid?
-          # Find or create labels and attach to issue
-          if params[:labels].present?
-            merge_request.add_labels_by_names(params[:labels].split(","))
-          end
-
           present merge_request, with: Entities::MergeRequest, current_user: current_user
         else
           handle_merge_request_errors! merge_request.errors
@@ -195,15 +192,11 @@ module API
             render_api_error!({ labels: errors }, 400)
           end
 
+          attrs[:labels] = params[:labels] if params[:labels]
+
           merge_request = ::MergeRequests::UpdateService.new(user_project, current_user, attrs).execute(merge_request)
 
           if merge_request.valid?
-            # Find or create labels and attach to issue
-            unless params[:labels].nil?
-              merge_request.remove_labels
-              merge_request.add_labels_by_names(params[:labels].split(","))
-            end
-
             present merge_request, with: Entities::MergeRequest, current_user: current_user
           else
             handle_merge_request_errors! merge_request.errors
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
diff --git a/lib/gitlab/fogbugz_import/importer.rb b/lib/gitlab/fogbugz_import/importer.rb
index 501d5a95547..65ee85ca5a9 100644
--- a/lib/gitlab/fogbugz_import/importer.rb
+++ b/lib/gitlab/fogbugz_import/importer.rb
@@ -74,8 +74,8 @@ module Gitlab
       end
 
       def create_label(name)
-        color = nice_label_color(name)
-        Label.create!(project_id: project.id, title: name, color: color)
+        params = { title: name, color: nice_label_color(name) }
+        ::Labels::FindOrCreateService.new(project.owner, project, params).execute
       end
 
       def user_info(person_id)
@@ -122,25 +122,21 @@ module Gitlab
           author_id = user_info(bug['ixPersonOpenedBy'])[:gitlab_id] || project.creator_id
 
           issue = Issue.create!(
-            project_id:   project.id,
-            title:        bug['sTitle'],
-            description:  body,
-            author_id:    author_id,
-            assignee_id:  assignee_id,
-            state:        bug['fOpen'] == 'true' ? 'opened' : 'closed'
+            iid:         bug['ixBug'],
+            project_id:  project.id,
+            title:       bug['sTitle'],
+            description: body,
+            author_id:   author_id,
+            assignee_id: assignee_id,
+            state:       bug['fOpen'] == 'true' ? 'opened' : 'closed',
+            created_at:  date,
+            updated_at:  DateTime.parse(bug['dtLastUpdated'])
           )
-          issue.add_labels_by_names(labels)
 
-          if issue.iid != bug['ixBug']
-            issue.update_attribute(:iid, bug['ixBug'])
-          end
+          issue_labels = ::LabelsFinder.new(project.owner, project_id: project.id, title: labels).execute
+          issue.update_attribute(:label_ids, issue_labels.pluck(:id))
 
           import_issue_comments(issue, comments)
-
-          issue.update_attribute(:created_at, date)
-
-          last_update = DateTime.parse(bug['dtLastUpdated'])
-          issue.update_attribute(:updated_at, last_update)
         end
       end
 
diff --git a/lib/gitlab/gfm/reference_rewriter.rb b/lib/gitlab/gfm/reference_rewriter.rb
index 78d7a4f27cf..a7c596dced0 100644
--- a/lib/gitlab/gfm/reference_rewriter.rb
+++ b/lib/gitlab/gfm/reference_rewriter.rb
@@ -58,7 +58,7 @@ module Gitlab
         referable = find_referable(reference)
         return reference unless referable
 
-        cross_reference = referable.to_reference(target_project)
+        cross_reference = build_cross_reference(referable, target_project)
         return reference if reference == cross_reference
 
         new_text = before + cross_reference + after
@@ -72,6 +72,14 @@ module Gitlab
         extractor.all.first
       end
 
+      def build_cross_reference(referable, target_project)
+        if referable.respond_to?(:project)
+          referable.to_reference(target_project)
+        else
+          referable.to_reference(@source_project, target_project)
+        end
+      end
+
       def substitution_valid?(substituted)
         @original_html == markdown(substituted)
       end
diff --git a/lib/gitlab/github_import/label_formatter.rb b/lib/gitlab/github_import/label_formatter.rb
index 2cad7fca88e..942dfb3312b 100644
--- a/lib/gitlab/github_import/label_formatter.rb
+++ b/lib/gitlab/github_import/label_formatter.rb
@@ -14,9 +14,13 @@ module Gitlab
       end
 
       def create!
-        project.labels.find_or_create_by!(title: title) do |label|
-          label.color = color
-        end
+        params  = attributes.except(:project)
+        service = ::Labels::FindOrCreateService.new(project.owner, project, params)
+        label   = service.execute
+
+        raise ActiveRecord::RecordInvalid.new(label) unless label.persisted?
+
+        label
       end
 
       private
diff --git a/lib/gitlab/google_code_import/importer.rb b/lib/gitlab/google_code_import/importer.rb
index 62da327931f..6a68e786b4f 100644
--- a/lib/gitlab/google_code_import/importer.rb
+++ b/lib/gitlab/google_code_import/importer.rb
@@ -92,19 +92,17 @@ module Gitlab
           end
 
           issue = Issue.create!(
-            project_id:   project.id,
-            title:        raw_issue["title"],
-            description:  body,
-            author_id:    project.creator_id,
-            assignee_id:  assignee_id,
-            state:        raw_issue["state"] == "closed" ? "closed" : "opened"
+            iid:         raw_issue['id'],
+            project_id:  project.id,
+            title:       raw_issue['title'],
+            description: body,
+            author_id:   project.creator_id,
+            assignee_id: assignee_id,
+            state:       raw_issue['state'] == 'closed' ? 'closed' : 'opened'
           )
 
-          issue.add_labels_by_names(labels)
-
-          if issue.iid != raw_issue["id"]
-            issue.update_attribute(:iid, raw_issue["id"])
-          end
+          issue_labels = ::LabelsFinder.new(project.owner, project_id: project.id, title: labels).execute
+          issue.update_attribute(:label_ids, issue_labels.pluck(:id))
 
           import_issue_comments(issue, comments)
         end
@@ -236,8 +234,8 @@ module Gitlab
       end
 
       def create_label(name)
-        color = nice_label_color(name)
-        Label.create!(project_id: project.id, name: name, color: color)
+        params = { name: name, color: nice_label_color(name) }
+        ::Labels::FindOrCreateService.new(project.owner, project, params).execute
       end
 
       def format_content(raw_content)
diff --git a/lib/gitlab/import_export.rb b/lib/gitlab/import_export.rb
index 181e288a014..eb667a85b78 100644
--- a/lib/gitlab/import_export.rb
+++ b/lib/gitlab/import_export.rb
@@ -3,7 +3,7 @@ module Gitlab
     extend self
 
     # For every version update, the version history in import_export.md has to be kept up to date.
-    VERSION = '0.1.4'
+    VERSION = '0.1.5'
     FILENAME_LIMIT = 50
 
     def export_path(relative_path:)
diff --git a/lib/gitlab/import_export/attribute_cleaner.rb b/lib/gitlab/import_export/attribute_cleaner.rb
index b9e4042220a..f755a404693 100644
--- a/lib/gitlab/import_export/attribute_cleaner.rb
+++ b/lib/gitlab/import_export/attribute_cleaner.rb
@@ -1,7 +1,7 @@
 module Gitlab
   module ImportExport
     class AttributeCleaner
-      ALLOWED_REFERENCES = RelationFactory::PROJECT_REFERENCES + RelationFactory::USER_REFERENCES
+      ALLOWED_REFERENCES = RelationFactory::PROJECT_REFERENCES + RelationFactory::USER_REFERENCES + ['group_id']
 
       def self.clean!(relation_hash:)
         relation_hash.reject! do |key, _value|
diff --git a/lib/gitlab/import_export/import_export.yml b/lib/gitlab/import_export/import_export.yml
index bb9d1080330..e6ecd118609 100644
--- a/lib/gitlab/import_export/import_export.yml
+++ b/lib/gitlab/import_export/import_export.yml
@@ -1,6 +1,7 @@
 # Model relationships to be included in the project import/export
 project_tree:
-  - :labels
+  - labels:
+      :priorities
   - milestones:
     - :events
   - issues:
@@ -9,7 +10,8 @@ project_tree:
       - :author
       - :events
     - label_links:
-      - :label
+      - label:
+          :priorities
     - milestone:
       - :events
   - snippets:
@@ -26,7 +28,8 @@ project_tree:
     - :merge_request_diff
     - :events
     - label_links:
-      - :label
+      - label:
+          :priorities
     - milestone:
       - :events
   - pipelines:
@@ -71,6 +74,10 @@ excluded_attributes:
     - :awardable_id
 
 methods:
+  labels:
+    - :type
+  label:
+    - :type
   statuses:
     - :type
   services:
diff --git a/lib/gitlab/import_export/json_hash_builder.rb b/lib/gitlab/import_export/json_hash_builder.rb
index 0cc10f40087..48c09dafcb6 100644
--- a/lib/gitlab/import_export/json_hash_builder.rb
+++ b/lib/gitlab/import_export/json_hash_builder.rb
@@ -65,11 +65,17 @@ module Gitlab
       # +value+ existing model to be included in the hash
       # +parsed_hash+ the original hash
       def parse_hash(value)
+        return nil if already_contains_methods?(value)
+
         @attributes_finder.parse(value) do |hash|
           { include: hash_or_merge(value, hash) }
         end
       end
 
+      def already_contains_methods?(value)
+        value.is_a?(Hash) && value.values.detect { |val| val[:methods]}
+      end
+
       # Adds new model configuration to an existing hash with key +current_key+
       # It may include exceptions or other attribute detail configuration, parsed by +@attributes_finder+
       #
diff --git a/lib/gitlab/import_export/project_tree_restorer.rb b/lib/gitlab/import_export/project_tree_restorer.rb
index 5a109f24f9f..7cdba880a93 100644
--- a/lib/gitlab/import_export/project_tree_restorer.rb
+++ b/lib/gitlab/import_export/project_tree_restorer.rb
@@ -110,7 +110,7 @@ module Gitlab
       def create_relation(relation, relation_hash_list)
         relation_array = [relation_hash_list].flatten.map do |relation_hash|
           Gitlab::ImportExport::RelationFactory.create(relation_sym: relation.to_sym,
-                                                       relation_hash: relation_hash,
+                                                       relation_hash: parsed_relation_hash(relation_hash),
                                                        members_mapper: members_mapper,
                                                        user: @user,
                                                        project_id: restored_project.id)
@@ -118,6 +118,10 @@ module Gitlab
 
         relation_hash_list.is_a?(Array) ? relation_array : relation_array.first
       end
+
+      def parsed_relation_hash(relation_hash)
+        relation_hash.merge!('group_id' => restored_project.group.try(:id), 'project_id' => restored_project.id)
+      end
     end
   end
 end
diff --git a/lib/gitlab/import_export/relation_factory.rb b/lib/gitlab/import_export/relation_factory.rb
index 9300f789e1b..dc630e76411 100644
--- a/lib/gitlab/import_export/relation_factory.rb
+++ b/lib/gitlab/import_export/relation_factory.rb
@@ -9,7 +9,10 @@ module Gitlab
                     builds: 'Ci::Build',
                     hooks: 'ProjectHook',
                     merge_access_levels: 'ProtectedBranch::MergeAccessLevel',
-                    push_access_levels: 'ProtectedBranch::PushAccessLevel' }.freeze
+                    push_access_levels: 'ProtectedBranch::PushAccessLevel',
+                    labels: :project_labels,
+                    priorities: :label_priorities,
+                    label: :project_label }.freeze
 
       USER_REFERENCES = %w[author_id assignee_id updated_by_id user_id].freeze
 
@@ -19,9 +22,7 @@ module Gitlab
 
       IMPORTED_OBJECT_MAX_RETRIES = 5.freeze
 
-      EXISTING_OBJECT_CHECK = %i[milestone milestones label labels].freeze
-
-      FINDER_ATTRIBUTES = %w[title project_id].freeze
+      EXISTING_OBJECT_CHECK = %i[milestone milestones label labels project_label project_labels project_label group_label].freeze
 
       def self.create(*args)
         new(*args).create
@@ -56,6 +57,8 @@ module Gitlab
 
         update_user_references
         update_project_references
+
+        handle_group_label if group_label?
         reset_ci_tokens if @relation_name == 'Ci::Trigger'
         @relation_hash['data'].deep_symbolize_keys! if @relation_name == :events && @relation_hash['data']
         set_st_diffs if @relation_name == :merge_request_diff
@@ -123,6 +126,20 @@ module Gitlab
         @relation_hash['target_project_id'] && @relation_hash['target_project_id'] == @relation_hash['source_project_id']
       end
 
+      def group_label?
+        @relation_hash['type'] == 'GroupLabel'
+      end
+
+      def handle_group_label
+        # If there's no group, move the label to a project label
+        if @relation_hash['group_id']
+          @relation_hash['project_id'] = nil
+          @relation_name = :group_label
+        else
+          @relation_hash['type'] = 'ProjectLabel'
+        end
+      end
+
       def reset_ci_tokens
         return unless Gitlab::ImportExport.reset_tokens?
 
@@ -171,11 +188,9 @@ module Gitlab
         # Otherwise always create the record, skipping the extra SELECT clause.
         @existing_or_new_object ||= begin
           if EXISTING_OBJECT_CHECK.include?(@relation_name)
-            events = parsed_relation_hash.delete('events')
+            attribute_hash = attribute_hash_for(['events', 'priorities'])
 
-            unless events.blank?
-              existing_object.assign_attributes(events: events)
-            end
+            existing_object.assign_attributes(attribute_hash) if attribute_hash.any?
 
             existing_object
           else
@@ -184,14 +199,22 @@ module Gitlab
         end
       end
 
+      def attribute_hash_for(attributes)
+        attributes.inject({}) do |hash, value|
+          hash[value] = parsed_relation_hash.delete(value) if parsed_relation_hash[value]
+          hash
+        end
+      end
+
       def existing_object
         @existing_object ||=
           begin
-            finder_hash = parsed_relation_hash.slice(*FINDER_ATTRIBUTES)
+            finder_attributes = @relation_name == :group_label ? %w[title group_id] : %w[title project_id]
+            finder_hash = parsed_relation_hash.slice(*finder_attributes)
             existing_object = relation_class.find_or_create_by(finder_hash)
             # Done in two steps, as MySQL behaves differently than PostgreSQL using
             # the +find_or_create_by+ method and does not return the ID the second time.
-            existing_object.update(parsed_relation_hash)
+            existing_object.update!(parsed_relation_hash)
             existing_object
           end
       end
diff --git a/lib/gitlab/issues_labels.rb b/lib/gitlab/issues_labels.rb
index 1bec6088292..01a2c19ab23 100644
--- a/lib/gitlab/issues_labels.rb
+++ b/lib/gitlab/issues_labels.rb
@@ -18,8 +18,8 @@ module Gitlab
           { title: "enhancement", color: green }
         ]
 
-        labels.each do |label|
-          project.labels.create(label)
+        labels.each do |params|
+          ::Labels::FindOrCreateService.new(project.owner, project).execute(params)
         end
       end
     end