mysociety/alaveteli

module AlaveteliPro
  module RequestSummaries
    extend ActiveSupport::Concern

    included do
      has_one :request_summary, as: :summarisable,
                                class_name: "AlaveteliPro::RequestSummary",
                                dependent: :destroy
      after_commit :create_or_update_request_summary,
                   on: [:create, :update]
    end

    # Creates a RequestSummary item for this model on first save, or updates
    # the existing one otherwise.
    def create_or_update_request_summary
      if should_summarise?
        self.request_summary =
          AlaveteliPro::RequestSummary.create_or_update_from(self)
      elsif should_update_parent_summary?
        parent = request_summary_parent
        parent.create_or_update_request_summary unless parent.blank?
      end
    end

    # Should a particular instance of a model have a request summary made of
    # it? Override this if you want to have more fine-grained control over
    # which records get RequestSummaries made for them
    def should_summarise?
      true
    end

    # Should a particular instance of a model trigger an update to its parent
    # when its updated?
    def should_update_parent_summary?
      false
    end

    # Return the parent model instance that should be updated if
    # #should_update_parent_summary? returns true
    def request_summary_parent
      nil
    end

    def request_summary_body
      raise NotImplementedError("You must implement this method in the " \
                                "class that includes this concern")
    end

    def request_summary_public_body_names
      raise NotImplementedError("You must implement this method in the " \
                                "class that includes this concern")
    end

    def request_summary_categories
      raise NotImplementedError("You must implement this method in the " \
                                "class that includes this concern")
    end
  end
end