controller helpers for URLs

gistfile1.rb

# I'm looking for URL helpers that allow me to generate URLs from within the controller.

# All controllers inherit from a common base:

class UsersController < ApplicationController
  …
end

# This is an API, not a web site: there are no views. Instead, controller methods
# use ApplicationController#render_result() to format the result in the requested
# format (we support several reply formats, for user convenience).

UsersController < ApplicationController
  def index
    result = do_stuff()
    render_result(result)
  end
  …
end

# Within ApplicationController#render_result(), I want to compose URLs that are based
# in part on the actual, concrete controller class name. The URLs point to the on-line
# documentation for the resource:

ApplicationController << ActionController::Base
    def render_result(result, status=200)

      result['links'] ||= {}
      result['links'].merge!( { :rel => 'help', 
        :href => "/1/doc/#{self.class.to_s.snakecase[/(.*)_controller/, 1]}" } )
    end
    respond_to do |format|
      format.json { render :json => result, :status => status }
      format.xml { render :xml => result, :status => status }
    end

end

# The above works, but generates only a relative URL. I'd like an absolute URL, like
#   https://api.codesion.com/1/doc/organizations
# The schema might, under various assumptions, but http or https; 
# the host name might be api.codesion.com or several other possibilities;
# the help url has "/doc" interpolated into the base URL for the resource.
# That is, "GET .../1/users" shows the list of users, while
#  "GET .../1/doc/users" shows the documentation for the various users methods.

# Is there some link_to or url_for or something like that that will do this?