order_factory.rb

class OrderFactory
  attr_accessor :order

  attr_reader :user

  def initialize user, params
    @user = user

    @params = params&.symbolize_keys || {}

    @products = params.delete(:products)

    @discount_code = params.delete(:discount_code)
  end

  def create!
    Order.transaction do
      initialize_order

      build

      Calculator.new(order).calculate

      order.save!

      after_create_callbacks
    end
  end

  def build
    @products.map do |params|
      PurchaseFactory.build order: order, params: params
    end

    order.attributes = @params

    order.location_id ||= DeliveryZone.find_by_postal_code(order.postal_code).id

    order.out_of_worktime = !delivery_zone.open? if order.in_zone?

    build_discount

    order
  end

  private
  def initialize_order
    self.order = user.orders.initialize_with_default_params
  end

  def build_discount
    discount = DiscountFinder.find(user, @discount_code)

    case discount.class.name
    when 'Coupon'
      @order.coupon = discount
    when 'GiftVoucher'
      @order.gift_voucher = discount
    end
  end

  def after_create_callbacks
    user.update location_id: order.location_id, orders_total: user.orders_total += order.total

    order.update alcohol: order.categories.alcohol.any?, previous_total: order.total

    user.decrement! :points, order.total_points

    if order.coupon&.single_use?
      order.coupon.update active: false
    end

    V2::OrderMailer.delay(queue: :email).email order
  end

  class << self
    def create! user: nil, params: nil
      new(user, params).create!
    end
  end
end