class Item
  include DataMapper::Resource

  property      :name,                  String, :key => true
  has n,        :dosages

  has n,        :producing_recipes,     :class_name => 'Recipe',
                                        :child_key => [:product_name]
  has n,        :consuming_recipes,     :class_name => 'Recipe',
                                        :through => :dosages,
                                        :remote_relationship_name => :recipe

  # Only this one is not working
  has n,        :derivatives,           :class_name => 'Item',
                                        :through => :consuming_recipes,
                                        :near_relationship_name => :product
  has n,        :materials,             :class_name => 'Item',
                                        :through => :producing_recipes,
                                        :remote_relationship_name =>
                                                :ingredients,
                                        :child_key => [:product_name]
end

class Recipe
  include DataMapper::Resource

  property      :id,                    Serial
  belongs_to    :product,               :class_name => 'Item',
                                        :child_key => [:product_name]
  has n,        :dosages
  has n,        :ingredients,           :class_name => 'Item',
                                        :through => :dosages,
                                        :remote_relationship_name => :item
end


class Stack
  include DataMapper::Resource
  property      :id,                    Serial
  property      :type,                  Discriminator
  property      :quantity,              Integer
  property      :item_name,             String

  belongs_to    :item
end

class Dosage < Stack
  property      :recipe_id,             Integer
  belongs_to    :recipe
end