class ActiveModelSerializers::Model

def self.attributes(*names)
  self.attribute_names |= names.map(&:to_sym)
  # Silence redefinition of methods warnings
  ActiveModelSerializers.silence_warnings do
    attr_accessor(*names)
  end
end

def self.derive_attributes_from_names_and_fix_accessors
  unless included_modules.include?(DeriveAttributesFromNamesAndFixAccessors)
    prepend(DeriveAttributesFromNamesAndFixAccessors)
  end
end

def cache_key
  ActiveSupport::Cache.expand_cache_key([
    self.class.model_name.name.downcase,
    "#{id}-#{updated_at.strftime('%Y%m%d%H%M%S%9N')}"
  ].compact)
end

def id
  attributes.fetch(:id) do
    defined?(@id) ? @id : self.class.model_name.name && self.class.model_name.name.downcase
  end
end

def initialize(attributes = {})
  attributes ||= {} # protect against nil
  @attributes = attributes.symbolize_keys.with_indifferent_access
  @errors = ActiveModel::Errors.new(self)
  super
end

def updated_at
  attributes.fetch(:updated_at) do
    defined?(@updated_at) ? @updated_at : File.mtime(__FILE__)
  end
end