normalize_host

# File actionpack/lib/action_dispatch/http/url.rb, line 136
        def normalize_host(_host, options)
          return _host unless named_host?(_host)

          tld_length = options[:tld_length] || @@tld_length
          subdomain  = options.fetch :subdomain, true
          domain     = options[:domain]

          host = ""
          if subdomain == true
            return _host if domain.nil?

            host << extract_subdomains_from(_host, tld_length).join('.')
          elsif subdomain
            host << subdomain.to_param
          end
          host << "." unless host.empty?
          host << (domain || extract_domain_from(_host, tld_length))
          host
        end