PHP Webhook setup for STRAVA API

webhook.php

<?php

if (isset($_GET['hub_challenge'])) {
    $data = ['hub.challenge' => $_GET['hub_challenge']];
    header("HTTP/1.1 200 OK");
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode($data);
    
    exit;
}

$client_id = '5';
$client_secret = '7b2946535949ae70f015d696d8ac602830ece412';
$callback_url = 'http://a-valid.com/url/webhook.php'; /* this should be the same URL as this page */
$verify_token = 'STRAVA';

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "https://www.strava.com/api/v3/push_subscriptions?client_id={$client_id}&client_secret={$client_secret}&callback_url={$callback_url}&verify_token={$verify_token}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => '',
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 0,
  CURLOPT_FOLLOWLOCATION => true,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => 'POST',
));

$response = curl_exec($curl);

curl_close($curl);

echo $response; /* will return the id or an error message */

// store and/or process id