<?php

/*
 * Takes a datetime, and returns a nice string, saying 
 * datetime of the form "YYYY-MM-DD HH:MM:SS"
 * 2 days ago, 10 minutes ago 1 hour ago, 3 weeks ago 
 * 4 months ago
 * 6 years ago
 * etc.
 */
function datetimeToRelative($datetime)
{
	/* Get the current time + DST */
	$current_time = time();

	/* Get the time of the post */
	$post_time = strtotime($datetime);


	/* Get when yesterday was */
	$yesterday_time = strtotime('12am yesterday');


	/* Work out the difference between the two dates; should be positive if in past */
	$relative_time     = $current_time - $post_time;
	$abs_relative_time = abs($relative_time);

	$when              = ($relative_time > 0 ? 'ago' : 'in the future');

	if ($abs_relative_time < 60) // Less than a minute 
		return $abs_relative_time.' '.($abs_relative_time > 1 ? 'seconds' : 'second').' '.$when;

	elseif ($abs_relative_time < 3600) // Less than an hour 
		return ($minutes = floor($abs_relative_time / 60)).' '.($minutes > 1 ? 'minutes' : 'minute').' '.$when;

	elseif ($post_time > $yesterday_time && $post_time < $yesterday_time + 86400) // Was it yesterday ?
		return 'yesterday';
	elseif ($abs_relative_time < 86400) // Less than a day ago 
		return ($hours = floor($abs_relative_time / 3600)).' '.($hours > 1 ? 'hours' : 'hour').' '.$when;	

	/* Since we have ruled out hours / mins / secs, now forget about the times etc. */
	$post_time         = strtotime(substr($datetime, 0, 10).' 00:00:00');

	$relative_time     = $current_time - $post_time;
	$abs_relative_time = abs($relative_time);

	if ($abs_relative_time < 604800) // Less than a week 
		return ($days = floor($abs_relative_time / 86400)).' '.($days > 1 ? 'days' : 'day').' '.$when;

	elseif ($abs_relative_time < 2629743) // Less than an month
		return ($weeks = floor($abs_relative_time / 604800)).' '.($weeks > 1 ? 'weeks' : 'week').' '.$when;

	elseif ($abs_relative_time < 31556926) // Less than an year
		return ($months = floor($abs_relative_time / 2629743)).' '.($months > 1 ? 'months' : 'month').' '.$when;

	else
		return ($years = floor($abs_relative_time / 31556926)).' '.($years > 1 ? 'years' : 'year').' '.$when;

}

?>