(PHP Extension) Automatically Refresh Token for 401 Unauthorized

Demonstrates how to automatically refresh an access token (without user interaction) when the token expires and a 401 Unauthorized response is received.

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

$tokenFilePath = 'qa_data/tokens/googleCalendar.json';

// Get our current access token.
$jsonToken = new CkJsonObject();
$success = $jsonToken->LoadFile($tokenFilePath);
if ($jsonToken->HasMember('access_token') == false) {
    print 'No access token found.' . "\n";
    exit;
}

$http = new CkHttp();
$http->put_AuthToken($jsonToken->stringOf('access_token'));

$jsonResponse = $http->quickGetStr('https://www.googleapis.com/calendar/v3/users/me/calendarList');
if ($http->get_LastMethodSuccess() != true) {

    if ($http->get_LastStatus() != 401) {
        print $http->lastErrorText() . "\n";
        print '----' . "\n";
        print $http->lastResponseBody() . "\n";
        exit;
    }

    // The access token must've expired. 
    // Refresh the access token and then retry the request.
    $oauth2 = new CkOAuth2();

    $oauth2->put_TokenEndpoint('https://www.googleapis.com/oauth2/v4/token');

    // Replace these with actual values.
    $oauth2->put_ClientId('GOOGLE-CLIENT-ID');
    $oauth2->put_ClientSecret('GOOGLE-CLIENT-SECRET');

    // Get the "refresh_token"
    $oauth2->put_RefreshToken($jsonToken->stringOf('refresh_token'));

    // Send the HTTP POST to refresh the access token..
    $success = $oauth2->RefreshAccessToken();
    if ($success != true) {
        print $oauth2->lastErrorText() . "\n";
        exit;
    }

    // The response contains a new access token, but we must keep
    // our existing refresh token for when we need to refresh again in the future.
    $jsonToken->UpdateString('access_token',$oauth2->accessToken());

    // Save the new JSON access token response to a file.
    $sbJson = new CkStringBuilder();
    $jsonToken->put_EmitCompact(false);
    $jsonToken->EmitSb($sbJson);
    $sbJson->WriteFile($tokenFilePath,'utf-8',false);

    print 'OAuth2 authorization granted!' . "\n";
    print 'New Access Token = ' . $oauth2->accessToken() . "\n";

    // re-try the original request.
    $http->put_AuthToken($oauth2->accessToken());
    $jsonResponse = $http->quickGetStr('https://www.googleapis.com/calendar/v3/users/me/calendarList');
    if ($http->get_LastMethodSuccess() != true) {
        print $http->lastErrorText() . "\n";
        exit;
    }

}

print $jsonResponse . "\n";
print '-----------------------------' . "\n";

?>