Room booking system?

I am not sure it is the right place to ask, but I will give it a shot.
I need to build a simple room reservation system in my CI app. There are six rooms, that are shared by a a bunch of people for (usually) ah hour- long sessions and I need to make the room booking system that would be easier to use than a shared Google spreadsheet.
Is there a php library that would simplify my task? If you have come accross anything like that, I am all ears...

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Donatas G.