# Set year, month, hour and day attributes in event.
my ($year, $month, $day, $hour);
if ( $event->{ts} ) {
   # ts are formatted like: 071015 21:43:52
   ($year, $month, $day, $hour)
      = $event->{ts} =~ /^(\d\d)(\d\d)(\d\d)\s+(\d\d):/;
}
MKDEBUG && _d('ymdh:', $year, $month, $day, $hour);
$event->{year}  = $year  || 0;
$event->{month} = $month || 0;
$event->{day}   = $day   || 0;
$event->{hour}  = $hour  || 24;  # 0 is a valid hour

# Filter event by year, month, hour and day if any corresponding
# environment variables are set.
my $ok = 1;
foreach my $filter ( qw(YEAR MONTH HOUR DAY) ) {
   if ( $ENV{$filter} && $event->{lc $filter} != $ENV{$filter} ) {
      MKDEBUG && _d('Event does not match', $filter, '=', $ENV{$filter});
      $ok = 0;
      last;
   }
}
$ok