[PHP] Relative date time : afficher une date comme Facebook ou Gmail

function rdatetime_en($timestamp, $ref = 0) {

	if ($ref < 1) $ref = time();

	$ts = $ref - $timestamp;
	$past = $ts > 0;
	$ts = abs($ts);

	if ($past) {
		$left = '';
		$right = ' ago';
	}
	else {
		$left = 'In ';
		$right = '';
	}

	if ($ts === 0) return 'Now';

	if ($ts === 1) return $left.'1 second'.$right;

	// Less than 1 minute
	if ($ts < 60) return $left.$ts.' seconds'.$right;

	$tm = floor($ts / 60);
	$ts = $ts - $tm * 60;

	// Less than 3 hours
	if ($tm < 3 && $ts > 0) {
		return $left.$tm.' minute'.($tm > 1 ? 's' : '').' and '
			.$ts.' second'.($ts > 1 ? 's' : '').$right;
	}

	// Less than 1 hour
	if ($tm < 60) {
		if ($ts > 0) {
			$left = 'About ';
		}
		return $left.$tm.' minutes'.$right;
	}

	$th = floor($tm / 60);
	$tm = $tm - $th * 60;

	// Less than 3 hours
	if ($th < 3) {
		if ($tm > 0) {
			return $left.$th.' hour'.($th > 1 ? 's' : '').' and '
				.$tm.' minute'.($tm > 1 ? 's' : '').$right;
		}
		else {
			return $left.$th.' hour'.($th > 1 ? 's' : '').$right;
		}
	}

	$refday = strtotime(date('Y-m-d', $ref));
	$refyday = strtotime(date('Y-m-d', $ref - 86400));

	// Same day, or yesterday
	if ($timestamp >= $refyday) {
		if ($timestamp < $refday) {
			$left = 'Yesterday ';
			$right = '';
		}
		else {
			$left = 'Today ';
			$right = '';
		}
		return $left.' at '.date('H:i a', $timestamp).' '.$right;
	}

	$td = floor($th / 24);
	$th = $th - $td * 24;

	// Less than 3 days
	if ($td < 3) {
		$left = 'Last ';
		$right = '';
		return $left.strtolower(date('l', $timestamp)).' at '
			.date('H:i', $timestamp).$right;
	}

	// Less than 5 days
	if ($td < 5) {
		return $left.$td.' days'.$right;
	}

	$refday = strtotime(date('Y-m-01', $ref));

	$right = '';

	// Same month
	if ($timestamp >= $refyday) {
		$left = 'The ';
		return $left.date('j F', $timestamp).$right;
	}

	return $left.date('F j, Y', $timestamp).$right;

}

Si vous constatez des réultats étranges, vérifiez bien que votre serveur est réglé sur le même fuseau horaire que vous. Si ce n'est pas le cas, vous pouvez changer facilement grace à la fonction :

bool date_default_timezone_set ( string $timezone_identifier )