Would I Be able to get full custody of my daughter?

My ex says he is going to the courthouse to file for custody of our daughter. We were never married. I feel that he shouldn't even get visitation. He's been in and out of jail. I had to call the cops on him before when I let him take my daughter and he called me on the phone threatening me that I would never see her again or find them. He does smoke marijuana and sells it. I have pictures of him smoking marijuana. He does not have a job, a high school dropout, living with his aunt. I do not feel my daughter should be around him at all and that he is an unfit parent. Considering all this, when we go to court for custody, do I have a good chance of winning full sole custody of my daughter?