Boys are LAME! Advise, pretty please?

So there's this guy and he's one of my bestest friends and I'm pretty sure there's something there but I don't know if I should just give up on him. He's realy depressed and when he gets in one of his moods he gets high he hangs out with his druggie friends and won't talk to me for like a week or two but when he's fine we'll talk non-stop. I'm always there for him and he's always there for me unless he's in one of his moods which happens about once every few months. I don't know, I really care about him and I know that he really cares about me but there's something that's really bugging him that he's not telling me and that's why he's been smoking so much recently. I also know that if I'm not there for him no one else will be. And when he realizes how he's been avoiding me he'll call me and apologize profusely or like make it up to me in some other way. I don't know I'm really scared about him before he stopped talking to me this time he had just started smoking ice a few days before. I feel like everytime we get close, is when he starts smoking and pushing me away. I've tried talking to him about it and all he says is that he can't always talk to me because he's out but if he's not high, he'll text me even if he is out with people. What should I do?