I don't think your son's situation is hopeless, but I do know that dwelling on the past is not going to help him or you. The past is over and done. Your son has served his time and did not receive any help while doing so.
I get how completely and utterly furious you are about your situation and your son's situation....I think we all hear the frustration and anger and fear in your posts. Your son should have been given addiction counseling and job training while in prison. I wish that he was...I wish many prisoners were helped, instead of simply housed away from society (although there are some who truly do need to simply be housed away from society--but that's another story).
Tragically, in your son's case, that did not happen.
I wish I could change the past for you, but I can't.
I know you wish you could change the past for your son, but you can't.
The only thing any of us can deal with is today, right now.
Right now, your son has the choice to begin again. He was not given the tools while in prison, but that does not mean that he can't acquire them now.
He can take life as life comes and make better choices when presented with obstacles.
He can look for another job that will allow him to work and NOT violate the mandate of the ankle bracelet.
He can look for face-to-face support for his struggle with addiction.
He can look for programs to help him free himself of his gang involvement (and I do know they have those in that part of the country).
I hope that tomorrow will be a little brighter for you both.