Google Docs API edit doc and save as PDF

I want a code snippet that takes the client id and secret of the google docs api then 1. edits a PULIC SHARED document from another user with a find and replace of %Name% placeholder with some other text (as well as %DATE%) 2. then exports that document as a PDF to the user. 3. reverts back to the original i.e. don't save changes or if you have to you can save the file with an ID