Learn WordPress as someone who knows PHP

I have been working in PHP for some time to work on my own project. Recently, I got a job opportunity to work with PHP, but it affects WordPress. I want to learn to use PHP in WordPress. I just want to be able to program while it's least concerned with CMS stuff. What good resources help me to program in a WordPress environment? And the good way I can program there. My dilemma is that I do not want to program a WordPress guru. How can I embed my programming skills directly into the WordPress framework?