index.php

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

$provider = new \League\OAuth2\Client\Provider\GenericProvider([
    'clientId'                => "CLIENT ID",     // Create your client on ripple.moe/dev/apps
    'clientSecret'            => "CLIENT SECRET",
    'redirectUri'             => 'https://your-website.com/',

    'urlAuthorize'            => 'https://ripple.moe/oauth/authorize',
    'urlAccessToken'          => 'https://ripple.moe/oauth/token',
    'urlResourceOwnerDetails' => 'https://ripple.moe/api/v1/ping',

    'scopeSeparator'          => ' ',
    'scopes'                  => ['read_confidential'],
]);

// If there is an error, show it
if (isset($_GET["error"])) {
    echo "error: $_GET[error]; error_description: $_GET[error_description]";
    return;
}

if (!isset($_GET['code'])) {

    // Fetch the authorization URL from the provider; this returns the
    // urlAuthorize option and generates and applies any necessary parameters
    // (e.g. state).
    $authorizationUrl = $provider->getAuthorizationUrl();

    // Get the state generated for you and store it to the session.
    $_SESSION['oauth2state'] = $provider->getState();

    // Redirect the user to the authorization URL.
    header('Location: ' . $authorizationUrl);
    exit;

// Check given state against previously stored one to mitigate CSRF attack
} elseif (empty($_GET['state']) || (isset($_SESSION['oauth2state']) && $_GET['state'] !== $_SESSION['oauth2state'])) {

    if (isset($_SESSION['oauth2state'])) {
        unset($_SESSION['oauth2state']);
    }

    exit('Invalid state');

} else {

    try {

        // Try to get an access token using the authorization code grant.
        $accessToken = $provider->getAccessToken('authorization_code', [
            'code' => $_GET['code']
        ]);

        // We have an access token, which we may use in authenticated
        // requests against the service provider's API.
        echo 'Access Token: ' . $accessToken->getToken() . "<br>";

        // Using the access token, we may look up details about the
        // resource owner.
        $resourceOwner = $provider->getResourceOwner($accessToken);

        var_export($resourceOwner->toArray());

    } catch (\League\OAuth2\Client\Provider\Exception\IdentityProviderException $e) {

        // Failed to get the access token or user details.
        exit($e->getMessage());

    }

}