“D’you think he meant you to do it?” said Ron. “Sending you your father’s cloak and everything?”
“Well, ” Hermione exploded, “if he did — I mean to say that’s terrible — you could have been killed.”
“No, it isn’t,” said Harry thoughtfully. “He’s a funny man, Dumbledore. I think he sort of wanted to give me a chance. I think he knows more or less everything that goes on here, you know. I reckon he had a pretty good idea we were going to try, and instead of stopping us, he just taught us enough to help. I don’t think it was an accident he let me find out how the mirror worked. It’s almost like he thought I had the right to face Voldemort if I could…”
(Harry Potter and the Sorcerer's Stone)

Is ‘it’ refer to something preceding or is it a dummy-it and ‘like-‘ clause is the semantic subject?

“D’you think he meant you to do it?” said Ron. “Sending you your father’s cloak and everything?”
“Well, ” Hermione exploded, “if he did — I mean to say that’s terrible — you could have been killed.”
“No, it isn’t,” said Harry thoughtfully. “He’s a funny man, Dumbledore. I think he sort of wanted to give me a chance. I think he knows more or less everything that goes on here, you know. I reckon he had a pretty good idea we were going to try, and instead of stopping us, he just taught us enough to help. I don’t think it was an accident he let me find out how the mirror worked. It’s almost like he thought I had the right to face Voldemort if I could…”
(Harry Potter and the Sorcerer's Stone)

Is ‘it’ refer to something preceding or is it a dummy-it and ‘like-‘ clause is the semantic subject?