[Question]: Custom AI

Before I wasting you experts' precious time at asking how to make an custom AI. I want to know if it's suitable and worth it, and is it really hard....

The map im making puts players into offences, their goal is to take down the AI's base, and i want the AI to be hard and chanllanging (to an average players alest)
The AI has to do these, they will have unlimited resources

Only Defending
Rebuild any pre-placed units that are lost in battle (Custom units included)
Units patrolling the base (Life like base)

Would i be able to achieve all these just by modify the exiesting AI or i have to create a custom one?

Thanks for your time reading this, and thanks in advance!

You can make a defending AI just by removing all attack assignments in the AI editor.
You have to make the patrolling through triggers. Perhaps you could detect when the AI sends replacements to guard positions and then send those units to patrol.

I have thought about the patrolling triggers, but that would be too much to do..

Thanks for the help once again :)