久し振りだね
めっちゃ久しぶりやん。
You're quite a stranger.=Hello stranger!
after a long separation
久しぶり!
the condition of being after a long period of time has elapsed
よう、久しぶり。
ねえ、久しぶりだね。
It is [has been] a long time since I saw you last.
It's been so long! Finally we have met.