$graph_url = 'https://graph.facebook.com/me?access_token=' . $result['access_token'];
                $fb_user = json_decode( file_get_contents( $graph_url ) );
                try {
                    $user = new Model_User( $fb_user->username );
                    $user_meta = new Model_User_Meta ( $user->get ( 'user_id' ) );
                    $user_meta->set_user_meta( '_facebook_id', $fb_user->id );
                    $user_meta->set_user_meta( '_last_logged_in', 'current_timestamp' );
                    $user_meta->save();
                } catch ( Exception $e ) {
                    if ( $e->getCode() === 0 ){
                        $password = Helper_Password::generate_password();
                        $hash = Helper_Password::hash_string( $password );
                        try {
                            $user = new Model_User();
                            $user->set( 'user_name', $fb_user->username );
                            $user->set( 'user_pass', $hash );
                            $user->set( 'user_email', $fb_user->email );
                            $user->set( 'user_status',( $fb_user->verified ? 'active' : 'inactive' ) );
                            $user->set( 'display_name', $fb_user->name );
                            $status = $user->save();
                            $user_meta = new Model_User_Meta ( $status->user_id );
                            $user_meta->set_user_meta( '_facebook_id', $fb_user->id );
                            $user_meta->set_user_meta( '_last_logged_in', 'current_timestamp' );
                            $user_meta->save();
                        } catch ( Exception $e ) {
                            throw $e;
                        }
                    } else {
                        throw $e;
                    }
                }