Need an enemy script that makes him wander and detect

Hey everyone. I'm working on a horror game based off the SCP foundation. I am hoping someone could provide a script for this (I just started unity. Never used javascript until then). The SCP is supposed to float around in an X,Z area, being able to clip walls. Once the player gets in a certain radius of the wandering SCP, he will stop wandering, and target the player. Once he targets the player, he will keep following the player (And clipping walls) until he gets to the player (then you die). So basically these things

-Wander around (floating and clipping walls in a certain X,Z area)

-Target the player at a certain radius

-Follow the player until he catches the player (Removing the radius)

I know it's a lot to ask for, but if someone could make a script doing that it would be awesome. Thanks in advance :)