class RecipeProxy

  attr_reader :recipe

  def initialize(recipe)
    @recipe = recipe
    parse_yields
  end

  def name
    @recipe.name
  end

  def density
    @density
  end

  def density?
    !self.density.nil?
  end

  def get_custom_unit_equivalent(custom_unit_name)
    unit = @custom_yields.detect { |vu| vu.unit.unit == custom_unit_name }
    known_unit = @unit_yields.first
    if unit && known_unit
      # ex:
      # custom_unit_name: "rolls"
      # yields: "3 rolls, 500 g"
      # desired return: 166.6 g

      ValueUnit.for(known_unit.value.value / unit.value.value, known_unit.unit)
    end
  end

  private

  def parse_yields
    @custom_yields = []
    @unit_yields = []
    @density = nil

    @recipe.yields_list.each do |y|
      begin
        vu = UnitConversion::parse(yield_string)
      rescue UnparseableUnitError
        vu = nil
      end

      if vu
        if vu.unit.nil?
          @custom_yields << ValueUnit.for(vu.value, 'servings')
        elsif vu.mass? || vu.volume?
          @unit_yields << vu
        else
          @custom_yields << vu
        end
      end

    end

    vol = @unit_yields.detect { |u| u.volume? }
    mas = @unit_yields.detect { |u| u.mass? }
    # ex
    # vol: 2 cups
    # mas: 7 oz
    if vol && mas
      @density = "#{mas.value.value / vol.value.value} #{mas.unit.original_unit}/#{vol.unit.original_unit}"
    end
  end

end