We have a Sites page with a form with one question asking for the applicant's website url. 
Instead of accepting the website provided, we are trying to pull out the domain from the provided url.  So if someone types in http://www.test.com/ or https://www.test.com/ or www.test.com/test1234, we'd want to use apex to insert the domain only (test.com).  Can anyone help?

I've started dabling in Lightning Components and worked through a tutorial last year and have done one of the trailheads a few days.  So I know how to code basic Lightning components and apps.  And I see in the metadata that these become AuraDefinitionBundles.  I also so an example of some code where a bit of JS is added to an empty VF page and that always a Lightning Component to be spun up inside a VF page.

What I want to do is take an exist VF page that is exposed to the internet as a SF "Sites" application and port it to Lightning.  What I included in the prior paragaph leads me to believe the page is codable.  Here's what I don't know.  When a Sites application is configured, you have to tell it what it has access to-- VF pages, Apex controllers, objects and fields, etc.  I don't know how you would give it access to the Aura bundle.  (Unless it's totally implicit and you don't have to and it automatically gets acces.)

Can anyone address the question of how to configure and deploy Sites application that includes a VF page that spins up an Lightning Component?