A stipulation of any probation is that you are not to consume illegal substances. If you have been given enough time to have a clean U/A and it comes up positive for an illegal substance, then your probation will be violated. That means you will do all or part of the suspended portions of the original sentence. Can you stay clean for a year? If not, tell your probation officer you have a serious drug problem and you need a higher level of treatment, ie: Intensive out patient. Or, just do the year in jail.

In any case, good luck to you.