Chromecast - see current status

I’m thinking about switching from FM to Chromecast for our main radio listening. It uses iHeartRadio, but I’ve done it before where I get the stream.

I see that a chromecast binding can be given a url, I assume I cant just put that on an item to push a url at the chromecast.

Is there a way of detecting it’s in use already (or not). I can see I’ll want a rule that says, if not in use and say, the alarm is disarmed (ie someone home), to play the ihearturl

With the chromecast audio, is is possible to go something like:

Switch play_radio "Radio" {chromecast:binding.playurl http:\\"}