openfoodnetwork/app/models/spree/stock/quantifier.rb

# frozen_string_literal: true

module Spree
  module Stock
    class Quantifier
      attr_reader :stock_items

      def initialize(variant)
        @variant = variant
        @stock_items = fetch_stock_items
      end

      def total_on_hand
        stock_items.sum(&:count_on_hand)
      end

      def backorderable?
        stock_items.any?(&:backorderable)
      end

      def can_supply?(required)
        total_on_hand >= required || backorderable?
      end

      private

      def fetch_stock_items
        # Don't re-fetch associated stock items from the DB if we've already eager-loaded them
        return @variant.stock_items.to_a if @variant.stock_items.loaded?

        Spree::StockItem.joins(:stock_location).
          where(:variant_id => @variant, Spree::StockLocation.table_name => { active: true })
      end
    end
  end
end