public function get_preview_classes() {

		$classes = '';

		if ( $this->is_complete() ) {
			$classes = ' is-complete has-icon';
		} elseif ( apply_filters( 'lifterlms_display_lesson_complete_placeholders', true ) && llms_is_user_enrolled( get_current_user_id(), $this->get( 'id' ) ) ) {
			$classes = ' is-incomplete has-icon';
		} elseif ( $this->is_free() ) {
			$classes = ' is-free has-icon';
		} else {
			$classes = ' is-incomplete';
		}

		return apply_filters( 'llms_get_preview_classes', $classes );
	}