Directed by Wai-keung Lau and Alan Mak
Written by Alan Mak and Felix Chong
AKA: Internal Affairs
IMDB

There's a mole working for a crime syndicate inside the police force. An officer goes undercover and infiltrates the crime syndicate. Over the course of ten years, their lives begin to blur, sometimes having to do things they would otherwise not do (especially the undercover cop).
Apparently The Departed is a remake of this film. I have never seen The Departed and it's looking less likely that I see it now. This film, however, was really great. Very well directed and acted. I was expecting more gun fights based on the Netflix description, but I was happy with what I got. A good morality story. Definitely worth watching.

8.5/10