use strict;
use warnings;

use Parallel::ForkManager;

$| = 1;

my $MAXIMUM_KIDS_IN_POOL =  3;
my $MAXIMUM_TIME_IN_POOL = 30; # Seconds

my $lifeguard = Parallel::ForkManager->new($MAXIMUM_KIDS_IN_POOL);

my @kids = qw( Ann Bob Cal Dan Eve Fay Gus Hal Ike Joe Kim Lee Meg );

$lifeguard->run_on_start(
    sub {
        my ($pid, $kid) = @_;
        print "\nThe lifeguard waves $kid into the pool\n";
    }
);

$lifeguard->run_on_finish(
    sub {
        my ($pid, $exit_code, $kid) = @_;
        print "\n$kid climbs out of the pool\n";
    }
);

$lifeguard->run_on_wait(
    sub {
       print ".";
    }, 0.3
);

my $number_of_kids = @kids;

print "\nThere are $number_of_kids kids in line at the pool\n\n@kids\n";

KID_IN_LINE:
for my $kid (@kids) {
    my $pid = $lifeguard->start($kid);

    next KID_IN_LINE if $pid != 0;

    srand();

    my $time = int(rand($MAXIMUM_TIME_IN_POOL)) + 1;

    print "\n$kid jumps into the pool\n";

    sleep $time;

    print "\nThe lifeguard orders $kid out of the pool after $time seconds\n";

    sleep 0.5;

    $lifeguard->finish();
}

print "\nAll the kids have been in the pool\n";

$lifeguard->wait_all_children();

print "\nAll the kids are out of the pool\n";

exit 0;