This looks like the class you need to watch out for:
So an xpath something like this will identify that the button is disabled:
//button[contains(@class, "button--disabled")]/div[@class="button-content"]
So you could reverse this with something like:
//button[not(contains(@class, "button--disabled"))]/div[@class="button-content"]
to detect that the button is enabled.
You could also use the aria-disabled attribute:
Or the disabled attribute:
Looks like you have lots of options to play with.
Dave.