#!/usr/bin/perl
use strict;
use warnings;

use Data::Validate qw(is_integer is_between);
use Date::Calc qw(:all);
use File::Basename;
use Lingua::EN::Inflect qw(ORD);

use lib 'lib';
use Date::Verify qw(four_digit_year month_name month_number day_number);

# commify, round, and pretty_number all make my numbers more readable.
# commify was found in the perldocs to put commas in numbers.
sub commify {
  local $_  = shift;
  1 while s/^([-+]?\d+)(\d{3})/$1,$2/;
  return $_;
}

my ($name, $birth_month, $birth_day, $birth_year) = @ARGV;
chomp(@ARGV);

if (!@ARGV || lc $name eq 'help') {
  my $file = basename($0);
  print "Please enter a single name and birthday: $file name month day year\n";
}
else {
  $birth_year  = four_digit_year($birth_year);
  $birth_month = month_number($birth_month);
  $birth_day   = day_number($birth_year, $birth_month, $birth_day);

  my $birth_month_name = month_name($birth_month);

  my $year  = (localtime)[5] + 1900;
  my $month = (localtime)[4] + 1;
  my $day   = (localtime)[3];

  # The following counts how many birthdays there has been.
  # It also figures out the next year for a birthday.
  # I'm still working on the kinks in the next birthday.
  my $birthdays;
  my $next_year;
  if ($birth_month > $month) {
    $birthdays = $year - $birth_year - 1;
    $next_year = $year;
  }
  elsif ($birth_month < $month) {
    $birthdays = $year - $birth_year - 1;
    $next_year = $year + 1;
  }  
  else {
    if ($birth_day > $day) {
      $birthdays = $year - $birth_year - 1;
      $next_year = $year;
    }
    else {
      $birthdays = $year - $birth_year;
      $next_year = $year + 1;
    }
  }

  my @birth     = ($birth_year, $birth_month, $birth_day);
  my @next_bday = ($next_year, $birth_month, $birth_day);
  my @today     = ($year, $month, $day);

  my $days_alive = Delta_Days(@birth,@today);
  my $days_til_next_bday = Delta_Days(@today,@next_bday);
  my $unbirthdays = $days_alive - $birthdays;

  my $unbirthday_text;
  if ($month == $birth_month && $day == $birth_day) {
    my $birthday = ORD($year - $birth_year);
    $unbirthday_text = "Happy $birthday birthday";
  }
  elsif ($unbirthdays > 0) { 
    my $ord_unbirthdays = commify(ORD($unbirthdays));
    $unbirthday_text = "Happy $ord_unbirthdays unbirthday";
  }
  else {
    $unbirthday_text = "Tomorrow is your first unbirthday";
  }

  print "$unbirthday_text, $name! You have $days_til_next_bday days until your next birthday on $birth_month_name $birth_day, $next_year.\n";
}