riboseinc/activeuuid

require "active_support"

module ActiveID
  # Include this module into all models which are meant to store UUIDs.
  module Model
    extend ActiveSupport::Concern

    included do
      class_attribute :_natural_key, instance_writer: false
      class_attribute :_uuid_namespace, instance_writer: false
      class_attribute :_uuid_generator, instance_writer: false
      self._uuid_generator = :random

      before_create :generate_uuids_if_needed
    end

    module ClassMethods
      def natural_key(*attributes)
        self._natural_key = attributes
      end

      def uuid_namespace(namespace)
        namespace = Utils.cast_to_uuid(namespace)
        self._uuid_namespace = namespace
      end

      def uuid_generator(generator_name)
        self._uuid_generator = generator_name
      end
    end

    def create_uuid
      if _natural_key
        # TODO if all the attributes return nil you might want to warn about this
        chained = _natural_key.map { |attribute| send(attribute) }.join("-")
        UUIDTools::UUID.sha1_create(_uuid_namespace || UUIDTools::UUID_OID_NAMESPACE, chained)
      else
        case _uuid_generator
        when :random
          UUIDTools::UUID.random_create
        when :time
          UUIDTools::UUID.timestamp_create
        end
      end
    end

    def generate_uuids_if_needed
      primary_key = self.class.primary_key
      primary_key_attribute_type = self.class.type_for_attribute(primary_key)
      if ::ActiveID::Type::Base === primary_key_attribute_type
        send("#{primary_key}=", create_uuid) unless send("#{primary_key}?")
      end
    end
  end
end