cela faisait longtemps

it had been a long time

→ cela
phrase Common #6,702
it had been a long time Often followed by que and a clause: cela faisait longtemps que… means “it had been a long time since…” or “it had been a long time that…”. In everyday speech, ça faisait longtemps is more common.
FR: Cela faisait longtemps que nous ne nous étions pas parlé.
EN: It had been a long time since we had spoken.

Cela faisait longtemps, M. Duan, vous nous manquiez.

It’s been a long time, Mr. Duan. We missed you.

— Adieu ma concubine (1993)

Cela faisait longtemps.

It's been a long time.

Cela faisait longtemps qu'il n'avait pas souri comme ça.

It had been a long time since he had smiled like that.

— Ne Zha (2019)