#!/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(10)) + 15;
        #maximum days to live is between 0 and 25 days
        $max = int(rand(25));
        #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 13 and 16 days
        $maturity = int(rand(14)) + 6;
        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(300)) + 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;
        print "\033[2J";
                  print "This data is based on the following properties and assumptions:\n";
                  print "1)  The average lifespan of a louse is between 25 and 50 days\n";
                  print "2)  The male to female ratio is roughly 50/50\n";
                  print "3)  The amount of time needed to grow from an egg into a fertile adult is between 14 - 20 days\n";
                  print "4)  Fertile (adult) females lay between 3 and 7 eggs per day.\n";
                  print "5)  Each egg takes between 7 to 10 days to hatch\n";
                  print "6)  Each nymph (hatched but not an adult) takes between 7 to 10 days to mature into an adult\n";
                  print "7)  This infection scenario was started by an adult, pregnant, female 14 days old with a lifespan of 32 days\n";
                  print "8)  I have found no documentation about how large an infestation of a single head can grow to.  This simulation also has no limits although I am sure there must be limiting factors.\n\n\n";
        print "================\n";

        print "DAY: $days\n";
        print "================\n";
        print "LICE: $n\n";
        print "LIVE LICE: $living\n";
        print "DEAD LICE: $deathtoll\n";
        print "FEMALES: $females\n";
        print "MALES: $males\n";
        print "EGG LAYERS (FEMALE ADULTS): $egglayers\n";
        print "NYMPHS (LITTLE/YOUNG): $toddlers\n";
        print "EGGS: $eggsacks\n";
        print "EGGS LAID TODAY: $eggslaidtoday\n";
        print "================\n";
                  $end = time - $start;
                  print "RUNTIME: $end\n";
        $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;
        }
}