How to add a button that will send an email to a costumer

So I’m trying to figure this out and was wondering if anyone could lead me in the right direction.

I basically wanna have a button in my product page that when a user is logged in, it will send them an email with more information of a product say a PDF for example.

Basically when a logged in costumer goes to a product page he sees the button that says "More information" then a script will fetch their email and send them the PDF to their email.