How to parse joint arguments in Bash?

Question

I already have a code snippet for parsing individual command-line arguments (in this case -a, -o, -O and their long forms). However, I want to parse combinations of these arguments, e.g. -ao or -aO.
It might be worth noting that I don't want -o and -O together, as they are opposites and only one of them is meant to be used at once.

Here's my current code snippet. All used variables here (AURF, DAO) are initialized with a value of 0.

while [[ $# -gt 0 ]]; do 
    case $1 in 
      -a|--aur) AURF=1;; 
      -o|--orphan) DAO=1;; 
      -O|--no-orphan) DAO=-1;; 
    esac 
    shift 
done