Triggering an email on events like entry status change

Hi all. I am beginning to wade into CodeIgniter and EE Extension development and am wondering where I’d need to start in order to solve a particular puzzle.

I’m wondering if there’s a way to send an email to a member as soon as an entry in a particular channel has it’s status changed.

An example is if a member creates a new entry, upon submission, it would get a default status of “Pending”. Once an admin processes the record, they would change that status to “Complete”. Once that status has changed, I would like to have EE send a templated email to the member confirming their request has been processed.

I’ve poked around devotee for plugins but have come up empty. If someone knows of a plugin which would help to these ends, then that would be fantastic! Ideally though, I would rather use this as an excuse to get up in some functions.

What would allow me to trigger an email from a status change? Where in the DevDocs would I find it (I’ve looked and am a little overwhelmed / didn’t find what I was looking for).

Any help would be most appreciated. Thanks in advance!