#!/bin/sh

awk -v timestamp=$1 '

# awkdate.sh - print UTC unix timestamps, like so
# $ sh awkdate.sh `date +"%s"` 
# May 17 19:39:31 UTC 2009
# this program does not print dates before 1970, it will error.
 
function isleap(year) {
        if (((year % 4) == 0 && (year % 100) != 0) || (year % 400) == 0)

                return 1;

	return 0;
}

function getyear(timestamp, year, is_leap) {
        year = 1970;

        while (timestamp >= 0) {
                is_leap = isleap(year);
                if (is_leap)
                        timestamp -= (366 * 86400);
                else    
                        timestamp -= (365 * 86400);

                year++;
        }

	if (is_leap)
		ts = timestamp + (366 * 86400);
	else
		ts = timestamp + (365 * 86400);

        year--;

        return year;
}

function getmonth(timestamp, year, is_leap, m) {

        is_leap = isleap(year);
        m[1] = 31;
        if (is_leap) 
                m[2] = 29;
        else
                m[2] = 28;

        m[3] = 31;      m[4] = 30; m[5] = 31;   m[6] = 30;
        m[7] = 31;      m[8] = 31; m[9] = 30;   m[10] = 31;
        m[11] = 30;     m[12] = 31;


        for (i = 1; i < 13; i++) {
                if ((timestamp - (m[i] * 86400)) < 0)
                        break;
                timestamp -= (m[i] * 86400);
        }

	ts = timestamp;

        return i;
}

function convmonth(month, mo)
{
        mo[1] = "Jan"; mo[2] = "Feb"; mo[3] = "Mar"; mo[4] = "Apr";
        mo[5] = "May"; mo[6] = "Jun"; mo[7] = "Jul"; mo[8] = "Aug";
        mo[9] = "Sep"; mo[10] = "Oct"; mo[11] = "Nov"; mo[12] = "Dec";

        return mo[month];
}

function getdays(timestamp, days) 
{
        days = 1;

        while ((timestamp -= 86400) >= 0)
                days++;

        timestamp += 86400;
	ts = timestamp;

        return days;
}

function gethour(timestamp, hour)
{
        hour = 0;
        while (timestamp >= 0) {
                timestamp -= 3600;
                hour++;
        }
        hour--;
	ts = timestamp + 3600;

        return hour;    
}

function getminute(timestamp, minute)
{
        minute = 0;
        while (timestamp >= 0) {
                timestamp -= 60;
                minute++;
        }
        minute--;

	ts = timestamp + 60;

        return minute;  
}

function getdate(timestamp, year, month, day, hour, minute, buf)
{
	if (timestamp > 2147483647 || timestamp < 0) {
		printf("I dont print time before 1970\n");
		exit(1);
	}
	ts = 0;

        year = getyear(timestamp);
	timestamp = ts;
        month = getmonth(timestamp, year);
	timestamp = ts;
        day = getdays(timestamp);
	timestamp = ts;
        hour = gethour(timestamp);
	timestamp = ts;
        minute = getminute(timestamp);
	timestamp = ts;
        buf = sprintf("%s %s %s:%02s:%02s UTC %s", convmonth(month), day , hour, minute, timestamp, year);
        return buf;
}

BEGIN {

        printf("%s\n", getdate(timestamp));

}'