Nevermind the clever writing but the issue has been known for years—and beautifully exploited with the selfhostable ready-made solution WhatsSpy Public since Feb 2015: https://gitlab.maikel.pro/maikeldus/WhatsSpy-Public/ It's not actively maintained anymore but Maikel deserves some credit for it.
Wanted to post the same. Note that this project used an own client, instead of scraping the webinterface. Which is by far superior, because you don't need an active charged phone and can scale much better. yowsup is still around and working.
Probably not, it used Chat-API [0], but the developer is kind of an asshole. But I admit, people just post stupid issues all the time. However I don't share the developers opinion that this was abused. My friends and I haven't received spam messages on Whatsapp. I admit that may be a small sample size, but still.
I did the same about mid 2015 using yowsup (Python API to Whatsapp). But it's was a private project because of legality concerns of hoarding so much data.
