module RoutingFilter
  class Chain < Array
    def <<(filter)
      filter.previous, last.next = last, filter if last
      super
    end
    alias push <<

    def unshift(filter)
      filter.next, first.previous = first, filter if first
      super
    end

    def run(method, *args, &final)
      active? ? first.run(method, *args, &final) : final.call
    end

    def active?
      RoutingFilter.active? && !empty?
    end
  end
end