#!/usr/bin/env perl
#
# pe was written by Omar Polo <op@openbsd.org> and is placed in the
# public domain.  The author hereby disclaims copyright to this source
# code.

use open ":std", ":encoding(UTF-8)";
use strict;
use warnings;
use v5.32;

use Digest::SHA;
use Encode qw(encode);
use IO::Poll qw(POLLOUT);

use SMArc qw(parse);

my $jobs = $ENV{'MAKE_JOBS'} // 1;

my $csumdir = $ENV{'CSUMDIR'};
die '$CSUMDIR undefined' unless defined $csumdir;

my $poll = IO::Poll->new();
for (1..$jobs) {
	open(my $kid, '|-', 'mexp') or die "can't exec mexp: $!";
	$poll->mask($kid => POLLOUT);
}

# get current thread checksum
sub thrsum {
	my $sha = Digest::SHA->new(256);
	$sha->add(encode('UTF-8', $_)) for @_;
	return $sha->hexdigest;
}

# get stored thread checksum
sub oldsum {
	my $tid = shift;
	open my $fh, '<', "$csumdir/$tid" or return "";
	my $sum = <$fh>;
	chomp $sum;
	return $sum;
}

# save thread checksum
sub savesum {
	my ($tid, $sum) = @_;
	open my $fh, '>', "$csumdir/$tid"
	    or die "can't open checksum file $csumdir/$tid: $!";
	say $fh $sum;
	close $fh;
}

sub process {
	my @entries = @_;

	return unless @entries;

	my $mail = parse $entries[0];
	die "wtf?" if $mail->{level} != 0;

	my $tid = $mail->{mid};
	my $thrsum = thrsum @_;
	my $oldsum = oldsum $tid;
	return if $thrsum eq $oldsum;

	die "poll: $!" if $poll->poll() == -1;
	my @handles = $poll->handles(POLLOUT) or die "no procs ready?";
	my $handle = $handles[int(rand(@handles))];
	print $handle $_ foreach @entries;

	savesum($tid, $thrsum);
}

if (`uname` =~ "OpenBSD") {
	use OpenBSD::Pledge;
	use OpenBSD::Unveil;

	unveil($csumdir, "rwc") or die "unveil $csumdir: $!";
	pledge("stdio rpath wpath cpath") or die "pledge: $!";
}

my @thread;
while (<>) {
	print; # continue the pipeline

	my $new_thread = m/^-/;
	if ($new_thread && @thread) {
		process @thread;
		@thread = ();
	}

	push @thread, $_;
}

process @thread if @thread;