This is my first post here, I'm sorry if I didn't follow any formatting or posting rules.
Original sentence, from a character's monologue:
願わくばこの時間が少しでも長く続くことを。。。
The English translation I have (not mine or official) is
I wish this moment could last even a little bit longer.....
I was quite confused by this conjugation, so I did some research on this site, and read this answer on how conditionals can be represented as 連用形 + あれば. So is 願わくば a contraction of 願わなくあれば / 願わなければ ?
But the thing I'm more confused about is, why is the negative conditional form used here in the first place? In the plain conditional, this looks something like "If I had to wish for something, it would be for this moment to continue for a little longer", but why the seemingly negative form? (Or is it even negative to begin with?)
Sorry for the double triple-loaded question, but one more thing: is this contraction of the conditional form commonly used? (Like in informal contexts?)
Edit: In case you're wondering why I made these somewhat far-fetched guesses: I guessed negative because of the わ (願う->願わない), and guessed conditional because of the ば (願う->願えば). Sorry >.<
Thank you for your time.