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<?php

function timediff($time, $now = null)
{
	if (is_null($now))
		$now = time();

	$periods = array(
		'second' => 1,
		'minute' => 60,
		'hour'   => 60,
		'day'    => 24,
		'week'   => 7,
		'year'   => 52,
	);

	$diff = abs($now - $time);
	$seconds = 1;
	$period = 'second';

	foreach ($periods as $name => $base)
	{
		if ($diff < $seconds * $base)
			break;

		$period = $name;
		$seconds *= $base;
	}

	$n = floor($diff / $seconds);

	return $n . ' ' . $period . (($n == 1) ? '' : 's');
}