#!/usr/bin/env php
<?php

$server = 'localhost';
$port = 2947;

set_time_limit(6);
ini_set('max_execution_time', 6);


$sock = @fsockopen($server, $port, $errno, $errstr, 2);
@fwrite($sock, "?WATCH={\"enable\":true}\n");
usleep(1000);
@fwrite($sock, "?POLL;\n");
usleep(1000);
for($tries = 0; $tries < 20; $tries++){
    $resp = @fread($sock, 2000);
    if (preg_match('/{"class":"POLL".+}/i', $resp, $m)){
        $resp = $m[0];
        break;
    }
}
@fwrite($sock, "?WATCH={\"enable\":false}\n");
@fclose($sock);

if ($resp) {
    $resp = json_decode($resp);

    if ($resp) {
        print "<<<gpsd>>>\n";

        if (!empty($resp->tpv[0])) {
            $tpv = $resp->tpv[0];
            print "mode:{$tpv->mode}\n";
        }

        if (!empty($resp->sky[0])) {
            $sky = $resp->sky[0];

            $sat_count = count($sky->satellites);
            $sat_used = count(array_filter($sky->satellites, "satellite_used"));

            print "hdop:{$sky->hdop}\n";
            print "vdop:{$sky->vdop}\n";
            print "satellites:{$sat_count}\n";
            print "satellites_used:{$sat_used}\n";
        }
    }
}

function satellite_used($sat) {
    return $sat->used;
}