Roomp was a startup operating in 2016-2018 in Russia.
It was a chain of hotels with its own booking system, integrated with Booking.com,Ostrovok and other OTAs.
It's long gone, but its code lives here
The code is abandoned and not supported, and uses old versions of Vue.js and PHP.
But here you can find useful ideas and approaches, if you're developing a similar system.
For any tech questions, you can reach out to me directly
Author: Alex Popov
Email: popov-a-e@yandex.ru