How do I create bot user with webhook on server side in MongooseIM?

This is what I want

1. A user(bot) that always shows status Online
2. When a message comes for the user, I will hit a webhook associated with the user
3. The response from the webhook request will be sent as reply to the sender
4. This user will be able to intercept any message (let's say for profanity moderation)
5. This user will be able to send message to anyone (let's say broadcast)
6. This user will come in every users roster as default(like echo bot of skype)

I can't seem to find any resource on how to achieve this. I've found a way to intercept the incoming packet in openfire but I don't see any easy way to do this with MongooseIM. I haven't started diving deep into the source code yet, still looking for a way to do this without touching the source code and locking myself to a specific version of MongooseIM.

Disclaimer: I'm on the MongooseIM core team.

There are multiple ways this could be achieved. The easiest way to achieve this depends on your familiarity with Erlang, the programming language MongooseIM is written in.

1. You won't need any Erlang to use the event pusher module with its HTTP backend and the default settings, but you'd need some Erlang to control what messages get forwarded to the HTTP service or to make more complex setups. To send messages back, you'd either need to use the MongooseIM REST API or connect as an ordinary XMPP client to the server using one of the many XMPP libs available out there. This is probably the best approach to achieve your goal.
2. You can skip using the event pusher and just connect your bot as an XMPP client written in any language whatsoever. The bot might have your business logic within or can forward messages it gets to the HTTP service.
3. If you're comfortable working in Erlang, then the mechanism to extend the server is called Hooks and handlers and is described in the official MongooseIM documentation. This requires writing code in Erlang and building from source, but does not necessarily require modifying upstream MongooseIM code.
4. You could use the XMPP component protocol, which allows to extend the functionality of an XMPP server, yet structure it as multiple services. The components may be written in any technology you want and the most popular XMPP libraries should support the component protocol out of the box.

Depending on your choice from the above list and the language and environment you prefer, you might have to pick an XMPP library to use. There are XMPP libs available for iOS (ObjC and Swift), Android (Java and Kotlin), Python, JavaScript, C, and even some emerging ones for Rust, Dart and possibly more.