QR Code standard for food products

qr_code_parser.rb

# Ruby code to parse a food product QR Code

class FoodQRParser
  class << self
    def parse(qr_string)
      data = {}
      sections = qr_string.split(';')

      data[:upc] = sections[0]
      data[:expiration_date] = sections[1].to_date
      data[:servings] = sections[2].to_i if sections[2]

      if nutritional_data = sections[3]
        data[:nutritional_information] = parse_nutritional_data(nutritional_data)
      end

      sections[4..-1].each do |remaining_section|
        section_type, section_data = remaining_section.split(':')

        case section_type.to_sym
        when :m
          data[:cooking_instructions] ||= {}
          data[:cooking_instructions][:microwave] = parse_microwave_instructions(section_data)
        else
          raise "Unrecognized section type (#{section_type})!"
        end
      end

      data
    end


    private

    NUTRITIONAL_DATA_FIELDS = %w(calories protein total_fat saturated_fat carbohydrates fiber sugars sodium).map(&:to_sym).freeze
    def parse_nutritional_data(nutrition_string)
      nutrition_values = nutrition_string.split(',').map {|s| s == "" ? nil : s.to_i }
      field_value_pairs = NUTRITIONAL_DATA_FIELDS.zip(nutrition_values)
      Hash[field_value_pairs]
    end

    COOKING_POWER_LEVELS = %w(high medium low defrost).each_with_object({}) {|l, h| h[l[0].upcase.to_sym] = l }.freeze
    def parse_microwave_instructions(cooking_string)
      data = {steps: []}
      base_power, steps = cooking_string.split(',')
      data[:base_power] = base_power.to_i

      steps.scan(/[LMHW]\d+|S/).each do |step|
        step_type, step_data = step[0].to_sym, step[1..-1]

        case step_type
        when :H, :M, :L
          power_level = COOKING_POWER_LEVELS[step_type]
          data[:steps] << { step: "cook", power: power_level, time: step_data.to_i }
        when :W
          data[:steps] << { step: "wait", time: step_data.to_i }
        when :S
          data[:steps] << { step: "stir" }
        else
          raise "Unrecognized step type! (#{step_type})!"
        end
      end

      data
    end
  end
end


FoodQRParser.parse("0013800103420;20140828;2;340,15,16,7,33,,2,820;m:700,H480SH180W60")

#=> {
#                         :upc => "0013800103420",
#             :expiration_date => Thu, 28 Aug 2014,
#                    :servings => 2,
#     :nutritional_information => {
#              :calories => 340,
#               :protein => 15,
#             :total_fat => 16,
#         :saturated_fat => 7,
#         :carbohydrates => 33,
#                 :fiber => nil,
#                :sugars => 2,
#                :sodium => 820
#     },
#        :cooking_instructions => {
#         :microwave => {
#                  :steps => [
#                 [0] {
#                      :step => "cook",
#                     :power => "high",
#                      :time => 480
#                 },
#                 [1] {
#                     :step => "stir"
#                 },
#                 [2] {
#                      :step => "cook",
#                     :power => "high",
#                      :time => 180
#                 },
#                 [3] {
#                     :step => "wait",
#                     :time => 60
#                 }
#             ],
#             :base_power => 700
#         }
#     }
# }