Conversationnal bot design patterns [on hold]

I'm building a bot for my company.
This bot makes API calls according to the user's answers.

For instance performing the action A would look like:
U: Do A
Bot: Sure, what is the answer to QA1 ?
U: xxx
Bot: What is the answer to QA2 ?
U: yyy
Bot: Done.

But some actions require other actions, for instance:
U: Do A
Bot: Sure, but first we need to do B, what is the answer to QB1 ?
U: xxx
Bot: We are done with B, what is the answer to QA1 ?
U: yyy
Bot: Done !

Do you have some articles about design patterns used in bots such as this one ?
or if you have previously build one, what approach would you recommend ?
(it seems to me things can go messy quite rapidly)