parsley/app/models/ingredient.rb

class Ingredient < ActiveRecord::Base
  include TokenizedLike

  validates :name, presence: true
  validates :density, density: true, allow_blank: true

  def self.search(query)
    tokens = query.to_s.split(' ')

    if tokens.empty?
      Ingredient.none
    else
      Ingredient.matches_tokens(:name, tokens)
    end
  end

  def ndbn=(value)
    @usda_food = nil
    super
  end

  def usda_food
    if self.ndbn.present?
      @usda_food ||= UsdaFood.find_by_ndbn(self.ndbn)
    else
      nil
    end
  end

  def usda_food_name
    if usda_food
      usda_food.long_description
    end
  end

  def set_usda_food(food)
    return unless food

    self.ndbn = food.ndbn
    self.water = food.water
    self.protein = food.protein
    self.lipids = food.lipid
    self.ash = food.ash
    self.kcal = food.kcal
    self.fiber = food.fiber
    self.sugar = food.sugar
    self.density = calculate_density(food.gram_weight_1, food.gram_weight_desc_1) || calculate_density(food.gram_weight_2, food.gram_weight_desc_2)
  end

  def calculate_density(grams, description)
    return nil if grams.blank? || description.blank?

    begin
      value_unit = UnitConversion.parse(description)
      if value_unit.volume?
        density_value = grams.to_d / value_unit.raw_value
        density_units = "g/#{value_unit.unit.unit}"
        density = UnitConversion.parse(density_value, density_units)
        return density.convert('oz/cup').to_s
      else
        return nil
      end
    rescue UnitConversion::UnparseableUnitError
      return nil
    end
  end

end