Check Before Authorizing a User in WordPress OAuth after using Authorization Code Grant Type.

gistfile1.txt

add_action( 'wo_authorization_code_authorize', 'before_authorization_test' );

function before_authorization_test( $user_id ) {
	$user_id = $user_id[0];

	$authorized = true;
  
  // Do user check and authorize if allowed
  
  // Present error is the user is not authorized
	if ( $authorized == false ) {
		$response = new WPOAuth2\Response();
		$response->setError( 400, 'unauthorized_user', 'Unauthorized User' );
		$response->send();
		exit;
	}
}