module MasterModel
  def self.included(base)
    #base.extend ClassMethods
    base.send :include, InstanceMethods
    base.class_eval do
      acts_as_list
      validates_uniqueness_of :name, case_sensitive: false
      validates :name, presence: true
      validate :name do
        valid_format?
      end
      validate :display_name do
        valid_yaml?
      end
      validates :display_name, presence: true
      before_validation :set_display_name, on: :create
      normalize_attributes :name
    end
  end

  module InstanceMethods
    def set_display_name
      self.display_name = "#{I18n.locale}: #{name}" if display_name.blank?
    end

    private
    def valid_format?
      unless name =~ /\A[A-Za-z][0-9A-Za-z_\s]*[0-9a-z]\Z/
        errors.add(:name, I18n.t('page.only_lowercase_letters_and_numbers_are_allowed'))
      end
    end

    def valid_yaml?
      begin
        YAML.load(display_name)
      rescue Psych::SyntaxError
        errors.add(:display_name, I18n.t('page.cannot_parse_yaml_header'))
      end
    end
  end
end