1 files changed, 53 insertions, 0 deletions
diff --git a/app/services/work_items/parent_links/base_service.rb b/app/services/work_items/parent_links/base_service.rb
new file mode 100644
index 00000000000..6f22e09a3fc
--- /dev/null
+++ b/app/services/work_items/parent_links/base_service.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module WorkItems
+  module ParentLinks
+    class BaseService < IssuableLinks::CreateService
+      extend ::Gitlab::Utils::Override
+
+      private
+
+      def set_parent(issuable, work_item)
+        link = WorkItems::ParentLink.for_work_item(work_item)
+        link.work_item_parent = issuable
+        link
+      end
+
+      def create_notes(work_item)
+        SystemNoteService.relate_work_item(issuable, work_item, current_user)
+      end
+
+      def linkable_issuables(work_items)
+        @linkable_issuables ||= if can_admin_link?(issuable)
+                                  work_items.select { |work_item| linkable?(work_item) }
+                                else
+                                  []
+                                end
+      end
+
+      def linkable?(work_item)
+        can_admin_link?(work_item) && previous_related_issuables.exclude?(work_item)
+      end
+
+      def can_admin_link?(work_item)
+        can?(current_user, :admin_parent_link, work_item)
+      end
+
+      override :previous_related_issuables
+      def previous_related_issuables
+        @previous_related_issuables ||= issuable.work_item_children.to_a
+      end
+
+      override :target_issuable_type
+      def target_issuable_type
+        'work item'
+      end
+
+      override :issuables_not_found_message
+      def issuables_not_found_message
+        format(_('No matching %{issuable} found. Make sure that you are adding a valid %{issuable} ID.'),
+          issuable: target_issuable_type)
+      end
+    end
+  end
+end