1 files changed, 73 insertions, 0 deletions
diff --git a/app/graphql/mutations/boards/lists/create.rb b/app/graphql/mutations/boards/lists/create.rb
new file mode 100644
index 00000000000..4f545709ee9
--- /dev/null
+++ b/app/graphql/mutations/boards/lists/create.rb
@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+module Mutations
+  module Boards
+    module Lists
+      class Create < Base
+        graphql_name 'BoardListCreate'
+
+        argument :backlog, GraphQL::BOOLEAN_TYPE,
+                 required: false,
+                 description: 'Create the backlog list'
+
+        argument :label_id, ::Types::GlobalIDType[::Label],
+                 required: false,
+                 description: 'ID of an existing label'
+
+        def ready?(**args)
+          if args.slice(*mutually_exclusive_args).size != 1
+            arg_str = mutually_exclusive_args.map { |x| x.to_s.camelize(:lower) }.join(' or ')
+            raise Gitlab::Graphql::Errors::ArgumentError, "one and only one of #{arg_str} is required"
+          end
+
+          super
+        end
+
+        def resolve(**args)
+          board  = authorized_find!(id: args[:board_id])
+          params = create_list_params(args)
+
+          authorize_list_type_resource!(board, params)
+
+          list = create_list(board, params)
+
+          {
+            list: list.valid? ? list : nil,
+            errors: errors_on_object(list)
+          }
+        end
+
+        private
+
+        def authorize_list_type_resource!(board, params)
+          return unless params[:label_id]
+
+          labels = ::Labels::AvailableLabelsService.new(current_user, board.resource_parent, params)
+            .filter_labels_ids_in_param(:label_id)
+
+          unless labels.present?
+            raise Gitlab::Graphql::Errors::ArgumentError, 'Label not found!'
+          end
+        end
+
+        def create_list(board, params)
+          create_list_service =
+            ::Boards::Lists::CreateService.new(board.resource_parent, current_user, params)
+
+          create_list_service.execute(board)
+        end
+
+        def create_list_params(args)
+          params = args.slice(*mutually_exclusive_args).with_indifferent_access
+          params[:label_id] = GitlabSchema.parse_gid(params[:label_id]).model_id if params[:label_id]
+
+          params
+        end
+
+        def mutually_exclusive_args
+          [:backlog, :label_id]
+        end
+      end
+    end
+  end
+end