rules.pl

% submit_rule in the actual project (go, scratch, etc.)
% generates a list of labels and whether they are ok, needed, or can be ignored.
% Most repos don't define a specific submit_rule; the server uses gerrit:default_submit.
%
% submit_filter, defined below, is applied to the output of submit_rule to adjust it.
% The adjustments are:
%
%  * do_not_review_filter: add a “rejected by Do-Not-Review label”
%    if the commit message says DO NOT REVIEW.
%
%  * do_not_submit_filter: add a “rejected by Do-Not-Submit label”
%    if the commit message says DO NOT SUBMIT.
%
%  * trust_filter: make sure that two different people have set
%    either Code-Review+2 or Trust+1 on the commit.
%
%  * self_review_filter: make sure that Code-Review+2
%    is from someone other than the author of the commit.
%
% Note that if you make any mistake in this file that causes
% a Prolog execution exception or makes submit_filter not succeed,
% the usual signal you get in Gerrit is that labels disappear from the UI for all CLs.
% Sometimes you get an internal error popup instead (syntax errors do this, for example).

submit_filter(In, Out) :-
	Gobot = user(5976),
	In =.. [submit | A],
	do_not_review_filter(Gobot, A, B),
	do_not_submit_filter(Gobot, B, C),
	trust_filter(Gobot, C, D),
	self_review_filter(Gobot, D, E),
	Out =.. [submit | E].

% We don't send email if the commit message says DO NOT REVIEW,
% so don't allow submit either.
% Case insensitive because the mail filter rules are.
do_not_review_filter(Gobot, In, Out) :-
	gerrit:commit_message_matches('[Dd][Oo][ \t\r\n]+[Nn][Oo][Tt][ \t\r\n]+[Rr][Ee][Vv][Ii][Ee][Ww]'),
	!,
	gerrit:commit_author(Id),
	Error = label('Do-Not-Review', reject(Id)),
	Out = [Error | In].

do_not_review_filter(Gobot, In, Out) :-
	Out = In.

% Don't allow submit of DO NOT SUBMIT commit message either.
% Case insensitive because DO NOT REVIEW is.
do_not_submit_filter(Gobot, In, Out) :-
	gerrit:commit_message_matches('[Dd][Oo][ \t\r\n]+[Nn][Oo][Tt][ \t\r\n]+[Ss][Uu][Bb][Mm][Ii][Tt]'),
	!,
	gerrit:commit_author(Id),
	Error = label('Do-Not-Submit', reject(Id)),
	Out = [Error | In].

do_not_submit_filter(Gobot, In, Out) :-
	Out = In.

% Check for two trusted author/reviewers, unless Self-Review-OK label set by project.
trust_filter(Gobot, In, Out) :- has_label('Self-Review-OK', In), !, Out = In.
trust_filter(Gobot, In, Out) :- trust2, !, Out = [label('Trusted', ok(Gobot)) | In].
trust_filter(Gobot, In, Out) :- Out = [label('Untrusted', reject(Gobot)) | In].

trust2 :- trust(U1), trust(U2), U1 \= U2.

trust(U) :- gerrit:commit_label(label('Code-Review', 2), U).
trust(U) :- gerrit:commit_label(label('Trust', 1), U).

% Reject self-code-review, unless Self-Review-OK label set by project.
%
% NOTE: Projects (= repos) that allow self-code-review and that do not require Trust+2
% (for example, the blog and proposal projects), can use this in rules.pl to set Self-Review-OK:
%
%	submit_rule(S) :-
%		Gobot = user(5976),
%		gerrit:default_submit(R),
%		R =.. [submit | A],
%		self_review_ok(Gobot, A, B),
%		S =.. [submit | B].
%
%	self_review_ok(Gobot, In, Out) :- Out = [label('Self-Review-OK', ok(Gobot)) | In].
%
self_review_filter(Gobot, In, Out) :- has_label('Self-Review-OK', In), !, Out = In.
self_review_filter(Gobot, In, Out) :- self_review, !, Out = [label('Self-Review', reject(Gobot)) | In].
self_review_filter(Gobot, In, Out) :- Out = In.

self_review :-
	gerrit:change_owner(Owner),
	gerrit:commit_label(label('Code-Review', 2), Owner).

% has_label checks whether the list contains the label L.
has_label(L, [label(L, _) | T]).
has_label(L, [_ | T]) :- has_label(L, T).