If drugs must be illegal, the offenders should be offered treatment, not prison, and drugs for medicinal uses should be legal. Weed has been shown by a Harvard study to fight cancer, but governments around the world are corrupt and refuse to respect peoples' right to choose. Gosh darned minimum word thing.
The best way to treat someone who deals harmful, addictive drugs like cocaine or heroin is simple: Lock them up in prison and take them away from them until they are no longer addicted. Now, what we need to work on is our prison "quality" - we need to make them undesirable crapholes, not four-star hotels, and there need to be psychologists on hand to help criminals cope with their addiction. They should have to serve a minimum sentence just so they can get away from it, instead of going through an unhelpful rehab program that still keeps them in touch with the stuff.