php/list_streams.php

<?php

// Call set_include_path() as needed to point to your client library.
require_once 'Google/Client.php';
require_once 'Google/Service/YouTube.php';
session_start();

/*
 * You can acquire an OAuth 2.0 client ID and client secret from the
 * {{ Google Cloud Console }} <{{ https://cloud.google.com/console }}>
 * For more information about using OAuth 2.0 to access Google APIs, please see:
 * <https://developers.google.com/youtube/v3/guides/authentication>
 * Please ensure that you have enabled the YouTube Data API for your project.
 */
$OAUTH2_CLIENT_ID = 'REPLACE_ME';
$OAUTH2_CLIENT_SECRET = 'REPLACE_ME';

$client = new Google_Client();
$client->setClientId($OAUTH2_CLIENT_ID);
$client->setClientSecret($OAUTH2_CLIENT_SECRET);
$client->setScopes('https://www.googleapis.com/auth/youtube');
$redirect = filter_var('http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'],
    FILTER_SANITIZE_URL);
$client->setRedirectUri($redirect);

// Define an object that will be used to make all API requests.
$youtube = new Google_Service_YouTube($client);

if (isset($_GET['code'])) {
  if (strval($_SESSION['state']) !== strval($_GET['state'])) {
    die('The session state did not match.');
  }

  $client->authenticate($_GET['code']);
  $_SESSION['token'] = $client->getAccessToken();
  header('Location: ' . $redirect);
}

if (isset($_SESSION['token'])) {
  $client->setAccessToken($_SESSION['token']);
}

// Check to ensure that the access token was successfully acquired.
if ($client->getAccessToken()) {
  try {
    // Execute an API request that lists the streams owned by the user who
    // authorized the request.
    $streamsResponse = $youtube->liveStreams->listLiveStreams('id,snippet', array(
        'mine' => 'true',
    ));

    $htmlBody .= "<h3>Live Streams</h3><ul>";
    foreach ($streamsResponse['items'] as $streamItem) {
      $htmlBody .= sprintf('<li>%s (%s)</li>', $streamItem['snippet']['title'],
          $streamItem['id']);
    }
    $htmlBody .= '</ul>';

  } catch (Google_Service_Exception $e) {
    $htmlBody .= sprintf('<p>A service error occurred: <code>%s</code></p>',
        htmlspecialchars($e->getMessage()));
  } catch (Google_Exception $e) {
    $htmlBody .= sprintf('<p>An client error occurred: <code>%s</code></p>',
        htmlspecialchars($e->getMessage()));
  }

  $_SESSION['token'] = $client->getAccessToken();
} else {
  // If the user hasn't authorized the app, initiate the OAuth flow
  $state = mt_rand();
  $client->setState($state);
  $_SESSION['state'] = $state;

  $authUrl = $client->createAuthUrl();
  $htmlBody = <<<END
  <h3>Authorization Required</h3>
  <p>You need to <a href="$authUrl">authorize access</a> before proceeding.<p>
END;
}
?>

<!doctype html>
<html>
<head>
<title>My Live Streams</title>
</head>
<body>
  <?=$htmlBody?>
</body>
</html>