<?php
$RRDFILE="/home/nirgal/ampy/power.rrd";

$info=rrd_lastupdate($RRDFILE);
if ($info === FALSE)
	$result=[
		'last_update' => 'unknown',
		'watts' => 'unknown'
	];
else
	$result=[
		'last_update' => $info['last_update'],
		'watts' => $info['data'][0]
	];
header("Content-Type: text/json");
echo(json_encode($result));
?>