nasa-cache.php

<?php

require __DIR__.'/vendor/autoload.php';


function dateToIso8601($date) {
	return $date->format("Ymd") . "T" . $date->format("His") . "Z";
}

function getCurrentDateUtc() {
	return new DateTime("now", new \DateTimeZone("UTC"));
}

function array_to_xml($student_info, &$xml_student_info, $root = true) {
    foreach($student_info as $key => $value) {
        if(is_array($value)) {
            $key = is_numeric($key) ? ($root? "Satellite" : "Coordinate") : $key;
            $subnode = $xml_student_info->addChild("$key");
            array_to_xml($value, $subnode, false);
        }
        else {
            $key = is_numeric($key) ? "item$key" : $key;
            $xml_student_info->addChild("$key","$value");
        }
    }
}

$observatories = file_get_contents("https://sscweb.sci.gsfc.nasa.gov/WS/sscr/2/observatories");

$observatoriesObj = simplexml_load_string($observatories) or die("Error: Cannot create object");


$activeObservatories = 
	from($observatoriesObj)
	//->where('$ob ==> new DateTime($ob["StartTime"]) < $dateMinusHour && new DateTime($ob["EndTime"]) > $datePlusHour')
	->where(function($item) {
		$obStartDate = DateTime::createFromFormat("Y-m-d\TH:i:s.u\Z", $item->StartTime);
		$obEndDate = DateTime::createFromFormat("Y-m-d\TH:i:s.u\Z", $item->EndTime);
		$datePlusHour = getCurrentDateUtc()->add(new DateInterval('PT1H'));
		$dateMinusHour = getCurrentDateUtc()->sub(new DateInterval('PT1H'));
		return $obStartDate < $dateMinusHour && $obEndDate > $datePlusHour;
	})
	->toList();


$activeObservatoriesChunks = array_chunk($activeObservatories, 40);
$satellites = array();

foreach ($activeObservatoriesChunks as $activeObservatoriesChunk) {
	$idList =
		from($activeObservatoriesChunk)
		->select(function($ob) {
			return $ob->Id;
		})
		->toString(",");

	$datePlusHour = dateToIso8601(getCurrentDateUtc()->add(new DateInterval('PT1H')));
	$dateMinusHour = dateToIso8601(getCurrentDateUtc()->sub(new DateInterval('PT1H')));

	$endpoint = "https://sscweb.sci.gsfc.nasa.gov/WS/sscr/2/locations/$idList/$dateMinusHour,$datePlusHour/gse/";
	$rawResponse = file_get_contents($endpoint);

	$obj = simplexml_load_string($rawResponse) or die("Error: Cannot create object");

	foreach ($obj->Result->Data as $satellite) {

		$observatory =
			from($activeObservatories)
			->where(function($ob) use($satellite) {
				// print_r($ob);
				// die;
				return strcmp($ob->Id, "$satellite->Id") == 0;
			})
			->firstOrDefault();

		if (!isset($observatory->Id)) {
			error_log("There was an error looking for the observatory ID $satellite->Id");
			die;
		}

		$sat = [
			'Id' => (string) $observatory->Id,
			'Name' => (string) $observatory->Name,
			'ResourceId' => (string) $observatory->ResourceId,
			'Coordinates' => array(),
		];

		$coordsCount = count($satellite->Time);

		for ($i = 0; $i < $coordsCount; $i++) {
			$sat["Coordinates"][] = [
				"Longitude" => (float)$satellite->Coordinates->Longitude[$i],
				"Latitude" => (float)$satellite->Coordinates->Latitude[$i],
				"Time" => (string)$satellite->Time[$i],
				"LocalTime" => (string)$satellite->Coordinates->LocalTime[$i]
			];
		}

		$satellites[] = $sat;
	}
}

$xml = new SimpleXMLElement('<Satellites/>');
array_to_xml($satellites, $xml);

$xmlDocument = new DOMDocument('1.0');
$xmlDocument->preserveWhiteSpace = false;
$xmlDocument->formatOutput = true;
$xmlDocument->loadXML($xml->asXML());

file_put_contents("satellites.xml", $xmlDocument->saveXML());