Help with log_analytics regex?

Hello! This is a topic I was exploring last year but never really got to the bottom of. My workload has shifted that I’m back looking at it.

So, we have, I believe, a custom format in our log files which I am trying to ingest into Piwik. The problem is that I really don’t know what I’m doing with writing the regular expressions. I’ve tried looking at a few examples but I don’t see how they fit together in relation to the original logs entry. Is anyone here able to offer some pointers or a link to some helpful documentation? I can provide examples if necessary, however there may be identifiable information I’ll need to remove.

Thanks in advance!