1 files changed, 60 insertions, 0 deletions
diff --git a/app/services/work_items/parent_links/create_service.rb b/app/services/work_items/parent_links/create_service.rb
new file mode 100644
index 00000000000..9940776e367
--- /dev/null
+++ b/app/services/work_items/parent_links/create_service.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+module WorkItems
+  module ParentLinks
+    class CreateService < IssuableLinks::CreateService
+      private
+
+      # rubocop: disable CodeReuse/ActiveRecord
+      def relate_issuables(work_item)
+        link = WorkItems::ParentLink.find_or_initialize_by(work_item: work_item)
+        link.work_item_parent = issuable
+
+        if link.changed? && link.save
+          create_notes(work_item)
+        end
+
+        link
+      end
+      # rubocop: enable CodeReuse/ActiveRecord
+
+      def linkable_issuables(work_items)
+        @linkable_issuables ||= begin
+          return [] unless can?(current_user, :admin_parent_link, issuable)
+
+          work_items.select do |work_item|
+            linkable?(work_item)
+          end
+        end
+      end
+
+      def linkable?(work_item)
+        can?(current_user, :admin_parent_link, work_item) &&
+          !previous_related_issuables.include?(work_item)
+      end
+
+      def previous_related_issuables
+        @related_issues ||= issuable.work_item_children.to_a
+      end
+
+      def extract_references
+        params[:issuable_references]
+      end
+
+      # TODO: Create system notes when work item's parent or children are updated
+      # See https://gitlab.com/gitlab-org/gitlab/-/issues/362213
+      def create_notes(work_item)
+        # no-op
+      end
+
+      def target_issuable_type
+        issuable.issue_type == 'issue' ? 'task' : issuable.issue_type
+      end
+
+      def issuables_not_found_message
+        _('No matching %{issuable} found. Make sure that you are adding a valid %{issuable} ID.' %
+          { issuable: target_issuable_type })
+      end
+    end
+  end
+end