limit_one_per_user_promotion_rule.rb

module Spree
  class Promotion
    module Rules
      class LimitOnePerUserPromotionRule < PromotionRule

        def eligible?(order)
          @email = order.email
          return completed_orders_using_promotion < 1
        end

        private
        attr_reader :email

        def completed_orders
          ::Spree::Order.where(email: email).complete
        end

        def promotions
          completed_orders.map{|o| o.adjustments.promotion}.flatten
        end

        def completed_orders_using_promotion
          promotions.select{|p| ::Spree::PromotionAction.find(p.originator_id).
                            activator_id == self.activator_id}.size
        end
      end
    end
  end
end