#!/usr/bin/perl -w
#
#
# This program attempts to model the process of an ongoing head lice
# infestation.
# It attempts to answer the question:
# "How many lice will there be in X days of infection if left untreated?"
#
# Written by Jason Butler, a father that was really creeped out by his
# childrens unfortunate (but quickly erradicated) head lice infestation.

use strict;
#use lib "/home/jbutler/scripts/lice";
# Using an object was not as fast as using a hash variable for spawning
# and looping through each louse (object).
#use lice_obj_pkg;

use Data::Dumper;

# Change this number to how many days you want iterate the infection through.
my $daysofinfection = 365;


my $debug = 0;

my %louse;

sub createlice {
                  my $rlouse = shift; #ref to %louse
        my $parent = shift; #parent louse
        my $n = keys %$rlouse;
        #if first louse then make it a female adult in prime egg laying status
        if ($n == 0) {
                print "CREATED FIRST LOUSE, SOURCE OF INFECTION\n" if ($debug > 0);
                $rlouse->{$n}->{'agedays'} = 14;
                $rlouse->{$n}->{'deathday'} = 32;
                $rlouse->{$n}->{'agetolay'} = 14;
                $rlouse->{$n}->{'sex'} = "female";
        #else, create a louse with random, yet realistic properties
        } else {
                my $dayofdeath=death_day();
                my $layday=maturity();
                my $gender=gender();
                print "CREATED ADDITIONAL LOUSE FROM louse number $parent\n" if ($debug > 0);
                $rlouse->{$n}->{'agedays'} = 0;
                $rlouse->{$n}->{'deathday'} = $dayofdeath;
                $rlouse->{$n}->{'agetolay'} = $layday;
                $rlouse->{$n}->{'sex'} = "$gender";
        }
}

sub death_day {
        my $min;
        my $max;
        my $dayofdeath;

        #minimum days to live is between 15 and 25 days
        $min = int(rand(11)) + 15;
        #maximum days to live is between 0 and 25 days
        $max = int(rand(26));
        #days to live = between 15 and 50 days.
        $dayofdeath = int(rand($max)) + $min;
        #print "DEBUG: day of death for louse will be on day $dayofdeath\n";
        return $dayofdeath;
}

sub maturity {
        my $maturity;

        #minimum days before able to lay eggs is between 14 and 20 days
        $maturity = int(rand(7)) + 14;
        return $maturity;
}

sub gender {
        my $gender;

        # 50/50 chance, male or female, is that accurate?  Don't know.
        if (int(rand(2)) == 1) {
                $gender = "female";
        } else {
                $gender = "male";
        }
        return $gender;
}

sub laid {
        my $eggs;

        # Lay between 1 and 7 eggs per day.
        $eggs = int(rand(8)) + 1;

        return $eggs;
}

my @louse;
my $userinput;
my $bugs = 0;
my $n = 0;
my $daystolive = 0;
my $age = 0;
my $agelay = 0;
my $deathtoll = 0;
my $living = 0;
my $laythismany = 0;
my $eggslaid = 0;
my $gender = "";
my $females = 0;
my $males = 0;
my $egglayers = 0;
my $eggslaidtoday = 0;
my $toddlers = 0;
my $eggsacks = 0;
my $start;
my $end;

for (my $days=1; $days != 0; $days++) {
        $n = keys %louse;
                  $start = time;
        #create another louse if criteria are met
        #iterate through each bug to handle any needed reproduction and update their attributes
        while ($bugs <= ($n-1)) {
                #print "DEBUG: BUGS: $bugs\n";
                $daystolive = $louse{$bugs}{'deathday'};
                $age = $louse{$bugs}{'agedays'};
                $age++;
                $louse{$bugs}{'agedays'} = $age;
                $age = $louse{$bugs}{'agedays'};
                if ($age >= $daystolive) {
                        $bugs++;
                        $deathtoll++;
                        next;
                }
                $gender = $louse{$bugs}{'sex'};
                if ($gender eq "male") {
                        $males++;
                        print "DEBUG: Gender: $gender\n" if ($debug > 0);
                } else {
                        $females++;
                        print "DEBUG: Gender: $gender\n" if ($debug > 0);
                }
                $agelay = $louse{$bugs}{'agetolay'};
                if ( ($age >= $agelay) && ($gender eq "female") ) {
                        $egglayers++;
                        $eggslaid = 0;
                        $laythismany = laid();
                        while ($eggslaid < $laythismany) {
                                createlice(\%louse,$bugs);
                                $eggslaid++;
                                $eggslaidtoday++;
                        }
                } elsif ( $age <= ($agelay/2) ) {
                        $eggsacks++;
                } else {
                        $toddlers++;
                }

                $bugs++;

                print "DEBUG: Louse " . ($bugs+1) . " will die on day $daystolive of its life.\n" if ($debug > 0);
                print "DEBUG: Louse " . ($bugs+1) . " is now $age days old\n" if ($debug > 0);
        }
        $bugs = 0;
        $userinput = " ";
        $n = keys %louse;
        $living = $n - $deathtoll;
                $end = time - $start;
        print "\033[2J";
                print <<UNTIL_END_REPORT;
This data is produced based on the following properties and assumptions:

(1)  The average lifespan of a louse is between 25 and 50 days, but more
     commonly between 25 to 35 days.
(2)  The male to female ratio is roughly 1:1.
(3)  The amount of time needed to grow from an egg into a fertile adult
     is between 14 - 20 days.
(4)  Fertile (adult) females lay between 3 and 7 eggs per day.
(5)  Each egg takes between 7 to 10 days to hatch.
(6)  Each nymph (hatched but not an adult) takes between 7 to 10 days
     to mature into an adult.
(7)  This infection scenario was started by an adult, pregnant, female
     14 days old with a lifespan of 32 days.
(8)  I have found no documentation about how large an infestation of a single
     head can grow to.  This simulation also has no limits,
     (other than memory storage), although I am sure there must be limiting
     factors (such as available space on the human head, hair count,
     hair length, environmental conditions, etc.

And let me just point out that this entire crop is inbred, just like real lice.
GROSS!!!!


================
DAY: $days
================
LICE: $n
LIVE LICE: $living
DEAD LICE: $deathtoll
FEMALES: $females
MALES: $males
EGG LAYERS (FEMALE ADULTS): $egglayers
NYMPHS (LITTLE/YOUNG): $toddlers
EGGS: $eggsacks
EGGS LAID TODAY: $eggslaidtoday
================
RUNTIME: $end
UNTIL_END_REPORT
        $egglayers = 0;
        $females = 0;
        $males = 0;
        $eggslaidtoday = 0;
        $toddlers = 0;
        $eggsacks = 0;
        #while ($userinput ne '') {
        #       $userinput = <STDIN>;
        #       chomp ($userinput);
        #}
        # create first louse; infection source.
        if ($n == 0) {
                $females++;
                createlice(\%louse,$n);
        }
        if ($days == $daysofinfection) {
                last;
        }
}