Use class in rails helper

product_price_helper.rb

module ProductPriceHelper
  # Render detailed product's price
  def product_price(product)
    ProductPrice.new(self, product).render
  end

  # render price for listing of products
  def listing_price(product)
    ProductPrice.new(self, product).render_for_listing
  end

  class ProductPrice < Struct.new(:view, :product)
    delegate :content_tag, :number_to_currency, to: :view

    def render
      price = if product.has_variations?
        price_range = if product.lowest_price && product.highest_price && product.lowest_price != product.highest_price
          "#{format_price(product.lowest_price)} - #{format_price(product.highest_price)}"
        elsif product.lowest_price
          format_price(product.lowest_price)
        else
          format_price(product.price)
        end
        price_tag('price', 'Price', price_range)

      elsif product.sale_price
        if product.price > product.sale_price
          price_tag('price', 'Price', format_price(product.price), 'cross-out') +
          price_tag('sale-price', 'Sale', format_price(product.sale_price)) +
          save_price_tag
        else
          price_tag('price', 'Price', format_price(product.price))
        end

      elsif product.list_price && product.amount_saved
        price_tag('list-price', 'List Price', format_price(product.list_price), 'cross-out') +
        price_tag('price', 'Price', format_price(product.price)) +
        save_price_tag

      else
        price_tag('price', 'Price', format_price(product.price))
      end

      content_tag(:div, price, id: 'product-prices')
    end

    def render_for_listing
      price = if product.lowest_price && product.highest_price && product.lowest_price != product.highest_price
        "#{format_price(product.lowest_price)} - #{format_price(product.highest_price)}"

      elsif product.lowest_price
        format_price(product.lowest_price)

      elsif product.sale_price
        if product.price > product.sale_price
          content_tag(:span, format_price(product.sale_price), class: 'sale-price') +
          content_tag(:span, format_price(product.price), class: 'cross-out')
        else
          format_price(product.price)
        end
        
      else
        format_price(product.price)
      end

      content_tag(:div, price, class: 'price')
    end

    private

    def price_tag(id, label, value, css_class='')
      content_tag(:div, id: id, class: "price #{css_class}") do
        content_tag(:div, label, class: 'label') + content_tag(:div, value, class: 'value')
      end
    end

    def save_price_tag
      content_tag(:div, id: 'amount-saved', class: 'price') do
        content_tag(:div, 'Saved', class: 'label') +
        content_tag(:div, format_price(product.amount_saved), class: 'value') +
        content_tag(:span, "(%#{product.percentage_saved})", id: 'percentage-saved')
      end
    end

    def format_price(amount)
      number_to_currency(amount / 100.0) if amount
    end
  end
end