Getting grasp of FA

Hi Everyone.

I'm trying to develop a couple of modules for FA (hopefully I'll be able to OS 'em, I still need to negotiate with my boss) but I'm still struggling to understand the basic architecture of FA. So far, I have been unable to determine which framework FA builds upon (and am almost convinced that it doesn't use any). Is it accurate?

I've read on the wiki that there's some sort of API, is module-oriented or is a global API? How difficult would it be to develop an RESTful SPA architecture on top of this API? Is there any unit tests showing how to use them?

I've run PHPMetrics on top of FA and it has revealed that a big chunk of FA is part of a PDF library. Is it a core depencency or is it reports-related only?

I think I'm missing some key conceptual organizational logic.

Any help will be highly appreciated.

Thanks in advance.

Vinicius Menezes