Create a static playlist

[PilatP]

Greetings.

I have a number of playlists and I want to generate a playlist per day for the interval 00h-12h and repeat the same playlist the rest of the day 12h-24h.
The playlist is based on some rules and its duration is limited to ~12 hours.
The next day I'd like to have a new playlist but based on the same rules.
If the radio is stopped I'd like it to continue broadcasting according to a predefined playlist, and not generate a new one.

Is there any way to create a predefined playlist?
Kind of

1. Run script
2. Search for a playlist
   a. if exists - play it
   b. if not exists - create one and play it

Sorry if it's lame.