Search results in wordpress, order by custom category order and time DESC

Question

Hello

I want to change default post search order to order:

• sample cat 1
  • sample post from cat 1
  • sample post from cat 1
• sample cat 2
  • sample post from cat 2
  • sample post from cat 3
• sample cat 3
  • etc..

So... I want to define category order and in search results will be sorted for this order and in category order will be date DESC. Only posts (no categories) will be visible.

Anybody have any idea?