Script to automatically enter document metadata

I need to enter document info as metadata into all of my Indesign documents as they are posted on the web as pdf docs so I wanted a script that would automaticaly enter the data once the document has been saved. I only need 3 fields to be filled.

My document is saved as "1234.1234 Document Name_D1" and the 3 fields I need are:

Document Title: only the wording after the code and before the underscore "Document Name"

Author: Is always "Company Name"

Keywords: only the "1234.1234" before the doc name

I'm not sure if this is at all possible so if it can be done automatically using only the whole document name then I'll take that instead.

Thanks,