class Product
  include SimplyStored::Couch

  property :name
  property :code
  property :price, type: Float

  #belongs_to :product_category
  has_and_belongs_to_many :product_categories, storing_keys: false
  belongs_to :supplier # direct! category is an aid
  has_many :product_orders

  attr_protected :supplier_id

  validates :name, presence: true
  validates :supplier_id, presence: true
  validates :price, presence: true, numericality: true
  view :by_supplier_id_and_id, key: [:supplier_id, :_id]

  after_save :persist_product_category_ids

  def product_category_ids=(ids)
    @product_category_ids = ids.select(&:present?)
    is_dirty
  end

private

  def persist_product_category_ids
    @product_category_ids ||= []
    existing_product_categories = product_categories

    # do nothing if nothing has changed
    return if @product_category_ids == existing_product_categories.map(&:id)

    # clear removed product categories
    existing_product_categories.reject{|pc| @product_category_ids.include?(pc.id) }.each{|pc| pc.remove_product(self) }


    # Add product to newly added product categories
    database.load(@product_category_ids - existing_product_categories.map(&:id)).each do |product_category|
      product_category.add_product(self)
    end
  end

end