Build an APP for my hotel

I want to create my own app for our Hotel where my guests can log in and rent my rooms. Where they will be able to communicate to us. We currently use booking.com, airbnb.com and our website to receive bookings. However we want to create an app so they can book it directly to there. This app should be able to connect calendars as well.
This is our website:
Michiehouse.com