MyBB import doesn't process on quoted posts PID and date

I’ve looked some more into this. The quote syntax for MyBB is:

[quote='username' pid='1234' dateline='1412029545']
...
[/quote]

In Discourse, it’s

[quote="username, post:12, topic:1234"]
...
[/quote]

How can I get the post number and topic ID from the post ID, via the API? process_mybb_post would need to be updated to take that into account; BTW, the import_id parameter isn’t used.