I need to export the chat history of an iMessage chat to either a text or PDF file.

I realize this is a common question, but I ask it again because preferably, each message should have beside it a record of:

1. The sender, and
2. a time/date-stamp for when the message was sent.

Is there a way to do this without having to download costly software? I am relatively experienced with Mac software and could potentially navigate scripting (I am most experienced with Python3, but have some limited experience with AppleScript), Terminal, and/or other techniques on the advanced side in this fix if walked through the steps.