function _close_comments_for_old_post( $open, $post_id ) {
  if ( ! $open ) {
    return $open;
  }

  if ( ! get_option( 'close_comments_for_old_posts' ) ) {
    return $open;
  }

  $days_old = (int) get_option( 'close_comments_days_old' );
  if ( ! $days_old ) {
    return $open;
  }

  $post = get_post( $post_id );

  
/** This filter is documented in wp-includes/comment.php */
  $post_types = apply_filters( 'close_comments_for_post_types', array( 'post' ) );
  if ( ! in_array( $post->post_type, $post_types ) ) {
    return $open;
  }

  // Undated drafts should not show up as comments closed.
  if ( '0000-00-00 00:00:00' === $post->post_date_gmt ) {
    return $open;
  }

  if ( time() - strtotime( $post->post_date_gmt ) > ( $days_old * DAY_IN_SECONDS ) ) {
    return false;
  }

  return $open;
}