Is there some guide somewhere that walks through the process of building something like Jedi for some other language (even an imaginary one)?

While it's tangential to this particular discussion, my goal (eventually) is to learn what I need to know to be able to build something like Jedi for PHP. There's only a handful of options for PHP code completion, and none of them provide the level of intelligence of a proprietary IDE like PhpStorm. That needs to change, IMO.