# encoding: utf-8

module Uuids

  # The module contains services for managing uuids.
  #
  # Any service implements the Observer pattern using the 'wisper' gem.
  # This means a service doesn't return results to its caller, but calls
  # a corresponding methods of its subscribers ("notifies subscribers").
  #
  # @see http://en.wikipedia.org/wiki/Observer_pattern Observer pattern.
  # @see http://github.com/krisleech/wisper the Wisper gem.
  module Services

    # Adds the uuid to the record.
    #
    # @example
    #   service = Uuids::Services::Add.new(
    #     record: #<ActiveRecord::Base ...>,
    #     value:  "42037503-2753-0570-3257-230403275325",
    #   )
    #   service.subscribe some_listener
    #   service.run
    class Add < Hexx::Service

      # @!scope class
      # @!method new(params)
      # Constructs the service object.
      # @example (see Uuids::Services::Add)
      # @param [Hash] params The list of service options.
      # @option params [ActiveRecord::Base] :record The record for adding uuid.
      # @option params [String] :value The uuid to be added to the record.
      allow_params :record, :value

      # @!method subscribe(listener, options = {})
      # Subscribes a listener to receive the service's notifications.
      # @example (see Uuids::Services::Add)
      # @param [Object] listener Any object can be subscribed as a listener.
      #   It is expected (but not required) the listener to respond to
      #   notifications, published by the {#run}.
      # @param [Hash] options The subscription options.
      # @option options [Symbol] :prefix (nil) The prefix to be added
      #   to notifications to provide valid listener method names to call.

      # Runs the service and publishes its results.
      # @example (see Uuids::Services::Add)
      # @change Creates the uuid assigned to the record.
      # @publish created(uuid,messages) when the uuid has been created.
      # @publish error(messages) when the uuid cannot be created.
      def run
        escape { create_uuid }
      rescue => err
        publish :error, err.messages
      else
        publish :created, uuid, messages
      end

      private

      attr_reader :uuid

      def create_uuid
        @uuid = Models::Uuid.create! record: record, value: value
        add_message "success", :created, uuid: uuid, record: name
      end

      def name
        t :record, id: record.id
      end
    end
  end
end