module Authority
  module Abilities
    extend ActiveSupport::Concern

    included do
      class_attribute :authorizer_name

      self.authorizer_name = "#{name}Authorizer"
    end

    module ClassMethods

      Authority.adjectives.each do |adjective|

        # Metaprogram needed methods, allowing for nice backtraces
        class_eval <<-RUBY, __FILE__, __LINE__ + 1
          def #{adjective}_by?(user)
            authorizer.#{adjective}_by?(user)
          end
        RUBY
      end

      def authorizer
        @authorizer ||= authorizer_name.constantize
      rescue NameError => e
        raise Authority::NoAuthorizerError.new("#{authorizer_name} does not exist in your application")
      end
    end

    Authority.adjectives.each do |adjective|

      # Metaprogram needed methods, allowing for nice backtraces
      class_eval <<-RUBY, __FILE__, __LINE__ + 1
        def #{adjective}_by?(user)
          authorizer.#{adjective}_by?(user)
        end

        def authorizer
          self.class.authorizer.new(self)
        end
      RUBY
    end

  end
end