<?php
header('Content-Type: application/json');

$file = 'online_devices.json';
$devices = [];

if (file_exists($file)) {
    $devices = json_decode(file_get_contents($file), true) ?: [];
}

// Optional: nur Geräte anzeigen, die in den letzten 5 Minuten online waren
$cutoff = strtotime('-5 minutes');
$online = array_filter($devices, function($d) use ($cutoff) {
    return strtotime($d['last_seen']) >= $cutoff;
});

echo json_encode(array_values($online));
?>