module GraphQL::Schema::Resolver::HasPayloadType

def field_class(new_class = nil)
  if new_class
    @field_class = new_class
  elsif defined?(@field_class) && @field_class
    @field_class
  else
    find_inherited_value(:field_class, GraphQL::Schema::Field)
  end
end

def generate_payload_type
  resolver_name = graphql_name
  resolver_fields = fields
  Class.new(object_class) do
    graphql_name("#{resolver_name}Payload")
    description("Autogenerated return type of #{resolver_name}")
    resolver_fields.each do |name, f|
      # Reattach the already-defined field here
      # (The field's `.owner` will still point to the mutation, not the object type, I think)
      add_field(f)
    end
  end
end

def object_class(new_class = nil)
  if new_class
    @object_class = new_class
  else
    @object_class || find_inherited_value(:object_class, GraphQL::Schema::Object)
  end
end

def payload_type(new_payload_type = nil)
  if new_payload_type
    @payload_type = new_payload_type
  end
  @payload_type ||= generate_payload_type
end