1 files changed, 58 insertions, 0 deletions
diff --git a/app/graphql/mutations/work_items/linked_items/base.rb b/app/graphql/mutations/work_items/linked_items/base.rb
new file mode 100644
index 00000000000..1d8d74b02ac
--- /dev/null
+++ b/app/graphql/mutations/work_items/linked_items/base.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+module Mutations
+  module WorkItems
+    module LinkedItems
+      class Base < BaseMutation
+        # Limit maximum number of items that can be linked at a time to avoid overloading the DB
+        # See https://gitlab.com/gitlab-org/gitlab/-/issues/419555
+        MAX_WORK_ITEMS = 3
+
+        argument :id, ::Types::GlobalIDType[::WorkItem],
+          required: true, description: 'Global ID of the work item.'
+        argument :work_items_ids, [::Types::GlobalIDType[::WorkItem]],
+          required: true,
+          description: "Global IDs of the items to link. Maximum number of IDs you can provide: #{MAX_WORK_ITEMS}."
+
+        field :work_item, Types::WorkItemType,
+          null: true, description: 'Updated work item.'
+
+        field :message, GraphQL::Types::String,
+          null: true, description: 'Linked items update result message.'
+
+        authorize :read_work_item
+
+        def ready?(**args)
+          if args[:work_items_ids].size > MAX_WORK_ITEMS
+            raise Gitlab::Graphql::Errors::ArgumentError,
+              format(
+                _('No more than %{max_work_items} work items can be linked at the same time.'),
+                max_work_items: MAX_WORK_ITEMS
+              )
+          end
+
+          super
+        end
+
+        def resolve(**args)
+          work_item = authorized_find!(id: args.delete(:id))
+          raise_resource_not_available_error! unless work_item.project.linked_work_items_feature_flag_enabled?
+
+          service_response = update_links(work_item, args)
+
+          {
+            work_item: work_item,
+            errors: service_response[:status] == :error ? Array.wrap(service_response[:message]) : [],
+            message: service_response[:status] == :success ? service_response[:message] : ''
+          }
+        end
+
+        private
+
+        def update_links(work_item, params)
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+end