submit_filter(In, Out) :-
  In =.. [submit | L1],
  only_author_can_submit(L1, L2),
  non_author_code_review(L2, L3),
  Out =.. [submit | L3].

%% CLs authored by non-Google developers can be submitted by others.
only_author_can_submit(S, S) :-
 gerrit:commit_author(_, _, Email),
  \+ regex_matches('@google.com', Email),
  !.

%% The Admin Bot (User ID: 6165) can submit on behalf of others.
only_author_can_submit(S, S) :-
 gerrit:current_user(Id),
  Id == user(6165),
  !.

only_author_can_submit(S, S) :-
  gerrit:commit_author(Id),
  gerrit:current_user(Id),
  !.

only_author_can_submit(S, [label('Patchset-Author', need(_)) | S]).

non_author_code_review(S1, S2) :-
  gerrit:commit_author(A),
  gerrit:commit_label(label('Code-Review', 2), R),
  R \= A, !,
  S2 = [label('Non-Author-Code-Review', ok(R)) | S1].

non_author_code_review(S, [label('Non-Author-Code-Review', need(_)) | S]).