How long has my dad been smoking weed?

So I went on vacation with my brother and my dad and we were in the hotel. My dad opened the nightstand drawer which is in between the two beds to get his wallet and I looked over and saw a bag with like stuff in it and he quickly tried to move it away. I knew it was weed but I tried to convince myself it wasn't. Later, they left me in the hotel by myself and I looked in the drawer and it was weed. I knew it was 100%. The next day, I went to go to his bag to find my toothbrush, and I found the same bag. We went home and I tried to forget about it, so I went into my parents room and went into his drawer to see if he had tape or a ruler or something but I found airtight box with about 4 bags in it. It was all of his weed. Next to it was, "cigarette burning paper". (Is that used to roll it?) and there was SO MANY packets of that. Like beyond a lot. His weed was green so does that mean its new? How long has he been smoking for? When I was younger I remember opening that drawer and him flipping out. Just today, he was on the phone with my uncle and said "I got the thing for you, I can come up this weekend to give it to you or maybe next weekend or something." But since me and my brother were there, he wouldn't say the real thing. My dad is literally my best friend, I love him to the world and I could never picturing him doing this. I was always daddys little girl, I'm only 15. I mean, he smokes cigarrettes, but I always thought it was only that. Never more. He goes to a bar once a week and drinks hardcore, do you think he smokes then? Is this worse than him drinking? I don't even want to look at him ever again....