# frozen_string_literal: true

module SolidusPromotions
  module Conditions
    class NthOrder < Condition
      include OrderLevelCondition

      preference :nth_order, :integer, default: 2
      # It does not make sense to have this apply to the first order using preferred_nth_order == 1
      # Instead we could use the first_order condition
      validates :preferred_nth_order, numericality: { only_integer: true, greater_than: 1 }

      # This is never eligible if the order does not have a user, and that user does not have any previous completed orders.
      #
      # Use the first order condition if you want a promotion to be applied to the first order for a user.
      # @param order [Spree::Order]
      def eligible?(order, _options = {})
        return false unless order.user

        nth_order?(order)
      end

      private

      def completed_order_count(order)
        order
          .user
          .orders
          .complete
          .where(Spree::Order.arel_table[:completed_at].lt(order.completed_at || Time.current))
          .count
      end

      def nth_order?(order)
        count = completed_order_count(order) + 1
        count == preferred_nth_order
      end
    end
  end
end
