AI vs AI Combat/Detection Method

Hello!

So working on a war-game type FPS involving several different factions with their allegiance changing throughout the game. The first big thing I need to figure out is getting a nice AI detection system down. Something like this but I'm sure there is a better/more efficient way that I'm not thinking of:

1. NPC identifying a potential target within a Radius (100 meters from itself)

2. Once target is identified maybe shoot a Raycast at them to pull more info

3. Need to individually keep track of said info, is target enemy? ally? null? remaining hp? etc.

I was thinking of making a single script that I could attach to all the NPCs but I'm really just guessing the best way to do this. Here is a visual aid of the above (not that you need it but wont hurt):

I've already submitted another question on how to handle the changing alliances which I got some nice help with and will implement soon, mad props to @Glurth and @Yatheesh-Raju390. But I was getting a bit ahead myself and realize I am having issues tackling the more basic issue of AI detection. Thanks to everyone taking the time to help me out, I'll try harder to figure out things for myself!