Stucked: regex pattern to display only domain name?

Hello,

Some users on my app can share links like that:

tripadvisor(.)fr/Attractions-g187079-Activities-Bordeaux_Gironde_Nouvelle_Aquitaine.html*

Or

tripadvisor(.)fr/Attraction_Products-g187079-zfc11918-zfg11867-Bordeaux_Gironde_Nouvelle_Aquitaine.html

It’s a bit messy. I would like to keep the destination but display a clean link with only the domain name:

tripadvisor(.)fr

How can i use Regex pattern to do that?

A big thanks for your help!

Sébastien