Wordpres: Clean up content

wordpress-cleanup-content.php

<?php

function __cleanup_post_data(){
  global $wpdb;
  
  // default wordpress "allowed html" for posts
  $allowed_tags = wp_kses_allowed_html( 'post' );

  // don't allow spans
  unset($allowed_tags['span']);

  // don't allow inline styles, nor classes
  foreach($allowed_tags as $tag => &$atts ){
    if (isset($atts['style'])){
      unset($atts['style']);
    }
    if (isset($atts['class'])){
      unset($atts['class']);
    }
  }
  
  // html comments pattern to search for
  $html_comment_pattern = '/<!-- [\s\S] ?*-->/s';

  // posts
  $posts = $wpdb->get_results('SELECT ID,post_content,post_excerpt FROM wp_posts WHERE post_content like "%style%" OR post_excerpt like "%style%"');

  foreach( $posts as $i =>  $post ){
    // clean content and remove comments
    $post->post_content = wp_kses( $post->post_content, $allowed_tags );
    $post->post_content = preg_replace( $html_comment_pattern, '', $post->post_content );

    // clean excerpt and remove comments
    $post->post_excerpt = wp_kses( $post->post_excerpt, $allowed_tags );
    $post->post_excerpt = preg_replace( $html_comment_pattern, '', $post->post_excerpt );

    // update row in the db with new values
    $update_sql = $wpdb->prepare("UPDATE {$wpdb->posts} SET post_content = %s, post_excerpt = %s WHERE ID = %d", 
      $post->post_content,
      $post->post_excerpt,
      $post->ID );
    
    $wpdb->query( $update_sql );
  }
}