#!/usr/bin/perl 

# This product includes software developed by Scott M Harrison (mailto://scott@mithrandir.com).
# Ported to perl and expanded by Troy Davis (mailto://troy@digissance.com)

use strict;
use Switch;
use Time::Local;
use Data::Dumper;

print tranquility_date() . "\n";
exit();


sub tranquility_date() {
	my ($dayOfYear, $yearOfCommonEra) = @_;
	my $show_date = 0;
	my ($second,$minute,$hour,$dayOfMonth,$month,$dayOfWeek);
	if (($dayOfYear =! /^\d+/) && ($dayOfYear > 0)  && ($dayOfYear < 367) && ($yearOfCommonEra =~ /^(-{1})*\d+$/)) {
		# Values passed in look legit
	} else {
		# Assume now in UTC time zone, Gregorian calendar
		$ENV{TZ} = ':/usr/share/zoneinfo/UTC'; 
		($second,$minute,$hour,$dayOfMonth,$month,$yearOfCommonEra,$dayOfWeek,$dayOfYear) = localtime();
		$dayOfYear++;
		$yearOfCommonEra += 1900;
		$show_date = 1;
	}

	my @daysOfWeek = ( "Thursday", "Friday", "Saturday", "Sunday", "Monday", "Tuesday", "Wednesday" );
	my @months = ( "Archimedes", "Brahe", "Copernicus", "Darwin", "Einstein", "Faraday", "Galileo", "Hippocrates", "Imhotep", "Jung", "Kepler", "Lavoisier", "Mendel" );
	my $daysInNonLeapYear = 365;
	my $daysInTranquilityMonth = 28;
	my $aldrinDay = 60;
	my $armstrongDay = 201;
	my $yearOfTranquility = 1969;
	my $isLeapYear = (
		(($yearOfCommonEra % 4) == 0) 
		&& (($yearOfCommonEra % 400) != 100) 
		&& (($yearOfCommonEra % 400) != 200)
		&& (($yearOfCommonEra % 400) != 300)
	);
	my $tranquilityDayOfYear = 0;
	my $specialDay = 0;
	my $day = 0;
	my $month = 1;
	my $year;
	my $afterArmstrongDay = $dayOfYear > $armstrongDay;

	if ($isLeapYear) {
		if ($dayOfYear > $aldrinDay) {
			$dayOfYear--;
		}
		elsif ($dayOfYear == $aldrinDay) {
			$specialDay = 1;
		}
	}
	if ($dayOfYear == $armstrongDay) {
		$specialDay = 2;
	}

	$tranquilityDayOfYear = $dayOfYear - $armstrongDay + ($afterArmstrongDay ? 0 : $daysInNonLeapYear);
	
	if ($specialDay == 0) {
		$month = sprintf("%d", ($tranquilityDayOfYear - 1) / $daysInTranquilityMonth);
		$day = $tranquilityDayOfYear - $month * $daysInTranquilityMonth;
	}
	elsif (($yearOfCommonEra == $yearOfTranquility) && ($specialDay == 2)) {
		$specialDay = 3;
	}

	$year = $yearOfCommonEra - $yearOfTranquility + ($afterArmstrongDay ? 1 : 0);
	if ($year <= 0) { $year--; }
	
	my $out = '';
	
	switch ($specialDay) {
		case 0 { $out .= $daysOfWeek[$day % 7] . ', ' . $months[$month] . " " . $day . ","; next }
		case 1 { $out .= "Aldrin Day $year"; next }
		case 2 { $out .= "Armstrong Day $year"; next }
		case 3 { $out .= "Moon Landing Day"; }
		}
	if (3 != $specialDay) {
		$out .= sprintf(" %d", abs($year));
		if ($year < 0) { $out .= " BT"; }
	}
	if ($show_date) {
		$out .= " " . sprintf("%02d", $hour) . ':' . sprintf("%02d", $minute) . ':' . sprintf("%02d", $second) . " UTC";
	}
	return $out;
}