Feed top products per vendor spree

feed_vendor_product.rb

module Feed
  class VendorProduct
    attr_accessor :vendor

    LIMIT = 4

    def initialize(vendor:, products:)
      @vendor = vendor
      @products = products
    end

    def products
      @products.blank? ? [] : @products
    end

    def self.call(vendor_ids, options={} )
      limit = options[:limit] || LIMIT
      return [] if vendor_ids.blank?

      vendors = Spree::Vendor.includes(:translations).find(vendor_ids)

      sub_query = query_product_in_vendor(vendor_ids).to_sql

      vendor_products = Spree::Product.select("*").from(" ( #{sub_query} ) AS spree_products")
                                .where(["spree_products.product_top_rank <= ?", limit])
                                .includes(:translations, master: :prices)

      vendor_products = vendor_products.to_a

      vendors.map do |vendor|
        products = vendor_products.select{|vendor_product| vendor_product.vendor_id == vendor.id}
        Feed::VendorProduct.new(vendor: vendor, products: products)
      end

    end

    def self.query_product_in_vendor(vendor_ids)
      select_stm = "spree_products.*, DENSE_RANK() OVER( PARTITION BY vendor_id ORDER BY created_at DESC ) AS product_top_rank"
      Feed::query_active_products.select(select_stm)
                                 .where(vendor_id: vendor_ids )
    end
  end
end