Untested — I didn't install the modules &mdash but the following should do the trick:
sub next_workday_9am {
my ($dt) = @_;
$dt = $dt->add(days => 1)
if $dt->hour() >= 9;
my $wday = $dt->wday();
if ($wday == 6) { $dt = $dt->add(days => 2); }
elsif ($wday == 7) { $dt = $dt->add(days => 1); }
$dt = $dt->truncate(to => 'day')->set(hour => 9);
return $dt;
}
my $sla_period = DateTime::SpanSet->from_set_and_duration(
set => DateTime::Set->from_recurrence(
recurrence => \&next_workday_9am,
),
hours => 8,
);
);
my $outage_start = 1124424000;
my $outage_end = 1140807162;
my $outage = DateTime::Span->from_datetimes(
start => DateTime->from_epoch($outage_start),
before => DateTime->from_epoch($outage_end),
);
print($sla_period->intersection($outage)->duration(), "\n");
DateTime::Set and related modules are definitely the way to go, although they are very daunting at first.