use warnings;
use strict;
use feature 'say';

# simulate the light and times db entries

my $light = 0;
my $on = '18:00';
my $hrs = 12;

my $now = time;
my ($start, $end);

# the following will be run once only when
# the main webapp is started. This sets the
# initial lights-on/off times into the db.
# of course, it'll just overwrite without first
# checking if the time was set previously or not

if (! $start){
    set_times();
    $start = $start - 24 * 3600;
    $end = $end - 24 * 3600;
}

# simulate event calling the light method

action_light();

say "light is on" if $light;

# object method that the event calls

sub action_light {
    if ($now > $start && $now < $end){
        if (! $light){
            $light = 1;
        }
    }
    elsif ($light) {
        $light = 0;
        set_times();
    }
}

# obj method called by action_light() and upon
# main webapp startup

sub set_times {
    my $time = time;
    $time += 60 until localtime($time) =~ /$on:/;
    $start = $time;
    $end = $start + $hrs * 3600;
}