Were there leaves on it earlier? Did they get diseased and fall off? If the canes are green and blooming I'd cut the buds off but leave as much cane as possible and let it regrow the leaves. It should rebloom again in about 6 weeks.

I'd ask how big is the container they're in also. and it could have been spider mites, i've had them defoliate a bush but it still bloom.

If the leaves fell off I'd take the buds off and let it re leaf
I would get some fungicide for it to prevent it from happening again.