Ask HN: Tool to post new referrers from Google Analytics to Slack?

I'm starting to build a tool that I imagine already exists. I want to have all new referrers from the real time section of Google Analytics be posted to a Slack channel. Hard requirements are:

1. Based on the real time data from Google Analytics. E.g. no one day time lag. No data from crawling the web.

2. Use Google Analytics Real Time API or something else approved by Google so it isn't going to get Google blocking my analytics account.

3. Only posts referrers that have never been seen before, or never been seen for some trailing X day window.