how do I get a spellID from when I mouse over a spell in game?

[Motanum]

Hey guys, newbie to addons developing here. So, with wow classic just getting started, and realizing I have to keep track of what rank of spells to use. SO I wrote a CPP project to simply calculate the mana efficiency of my spells. For example, rank 2 of fireball has a stat of 0.9 Damage per Mana, so I know that of all spells I have I should use that to get the most damage out of my mana pool.

But I am super lazy to have to input the values manually into my console application, so I thought, maybe I could make an AddOn that will tell me extra spell stats, like Damage Per Mana, when I simply moiuse over my spells, either from the Action Bar, or from the spellbook. So I thought, that it could be a simple enough project I could proabably make and then expand upon with other info I thought could be usefull.

I started the tutorial Creating WoW AddOns from Mayron, and I got to a stage where I have a simple message window with the name of my addon showing up.



But now I am quite lost as to where to go from here? I figured maybe have some kind of event listener so that when the player mouses over a spell, I could maybe get the SpellID, which then I could have a function check for Min Damage, Max Damage, Mana cost, and just do some math.

So for now, how do I get a spellID from when I mouse over a spell in game?