Imagine that someone thought he came up with an original idea. But actually I've heard that idea many times before. I want to express my exasperation, but I don't know which sentence is correct.
If other people had come up with the idea in the past then you would say "it had been done before." But I'm talking about something from present times, so I'm all confused now as to how to say it the right way
See: Use of "have had" , "had had", "has had" .
It had been done before implies a singularity and recency (present perfect tense), but it has been done before is plural and past tense (past perfect tense). [Implies means not critical but assumed, the recency is required and not implied for it to be had].
If there were a recent prior attempt (possibly multiple recent ones) then "it had been done before", but if it was done some time ago or multiple times (not recently) then "it has been done before".
By changing "had" to "had not" (hadn't) it is a negation of the above. The negation cancels the recency by imposing never upon the circumstances. So "has not" is that you are described by others as someone who didn't but "have not" is that you don't, as claimed by yourself or others ("I have not", "You have not", or third person singular "He has not" (talking like you are excluded from the conversation either by physical distance, or close up might be rudeness or lacking inclusiveness (shutting you out of the decision)).
That causes "has" to refer only to a third person, a "present perfect tense with a third person singular subject". Examples: "I or you have eaten", "I or you have not eaten", "He or she has eaten", but "They have eaten" or "They have not eaten".
The second, present perfect, expresses past event(s), but it's indefinite past, possibly recent but not necessary. If you were more specific, like "10 years ago" rather than "before", you'd need to use past tense, so "wasn't" instead of "hasn't been".
If your friend's idea is in present, then you should use present perfect, number 2.
But if your friend's idea is from the past, and you're expressing that it wasn't new then, then you should use number 1, past perfect, which expresses events before certain past event.
