Attempt at extracting subdomain mapping to a simple class for use with a whitelabel solution

application_controller.rb

require 'subdomain_mapper'
class ApplicationController < ActionController::Base
  before_filter :check_whitelabel

  def check_whitelabel
    sd = SubdomainMapper.new(request.subdomain)
    prepend_view_path(sd.whitelabel_view_path)
  end

end

config.yml

# scoped by env which makes dev easier
development:  &base
  # folder name which is located within app/whitelabels
  subdomains:
    shopping:
      # mapped subdomains
      values:
      - shopping
      - shopping.dev

test:
  <<: *base

production:
  <<: *base

subdomain_mapper.rb

class SubdomainMapper
  # maps the requested subdomain to one in the config file
  def initialize(key)
    @subdomain = key 
  end

  def reserved_subdomains
    APP_CONFIG['subdomains']
  end

  def with_key
    # we need to always return an array
    reserved_subdomains.find { |k,v| v['values'].include?(subdomain_key) } || []
  end

  def whitelabel_view_path
    "app/whitelabels/#{with_key.first}/views" if with_key.present?
  end

  def subdomain_key
    @subdomain
  end

end