Delete Image Size Files No Longer Registered

add_action( 'admin_menu', function () {
    add_management_page( 'Unused Image Sizes', 'Unused Image Sizes', 'manage_options', 'wpide-unused-sizes', function () {
        $registered = array_merge( get_intermediate_image_sizes(), array( 'full', 'original_image' ) );
        $uploads    = wp_get_upload_dir();
        $delete     = isset( $_POST['wpide_delete_sizes'] ) && check_admin_referer( 'wpide_unused_sizes' ) && current_user_can( 'manage_options' );
        $offset     = $delete ? 0 : ( isset( $_GET['offset'] ) ? absint( $_GET['offset'] ) : 0 );
        $found      = array();
        $bytes      = 0;
        $deleted    = 0;

        $ids = get_posts( array(
            'post_type'      => 'attachment',
            'post_mime_type' => 'image',
            'post_status'    => 'inherit',
            'posts_per_page' => 300,
            'offset'         => $offset,
            'fields'         => 'ids',
            'no_found_rows'  => true,
        ) );

        foreach ( $ids as $id ) {
            $meta = wp_get_attachment_metadata( $id );
            if ( empty( $meta['sizes'] ) || empty( $meta['file'] ) ) {
                continue;
            }
            $dir     = trailingslashit( $uploads['basedir'] ) . trailingslashit( dirname( $meta['file'] ) );
            $changed = false;
            foreach ( $meta['sizes'] as $size => $data ) {
                if ( in_array( $size, $registered, true ) || empty( $data['file'] ) ) {
                    continue;
                }
                $path = $dir . $data['file'];
                $found[ $size ] = ( isset( $found[ $size ] ) ? $found[ $size ] : 0 ) + 1;
                if ( file_exists( $path ) ) {
                    $bytes += filesize( $path );
                    if ( $delete && wp_delete_file_from_directory( $path, $uploads['basedir'] ) ) {
                        $deleted++;
                    }
                }
                if ( $delete ) {
                    unset( $meta['sizes'][ $size ] );
                    $changed = true;
                }
            }
            if ( $changed ) {
                wp_update_attachment_metadata( $id, $meta );
            }
        }

        echo '<div class="wrap"><h1>Unused Image Sizes</h1>';
        if ( $delete ) {
            printf( '<div class="notice notice-success"><p>%s</p></div>', esc_html( sprintf( 'Deleted %d file(s), freeing %s. Run again to process more images.', $deleted, size_format( $bytes, 1 ) ) ) );
        }
        printf( '<p>%s</p>', esc_html( sprintf( 'Checked %d images (starting at #%d). Sizes registered now: %s.', count( $ids ), $offset, implode( ', ', get_intermediate_image_sizes() ) ) ) );
        if ( $found && ! $delete ) {
            echo '<table class="widefat striped" style="max-width:520px"><thead><tr><th>Unregistered size</th><th>Files</th></tr></thead><tbody>';
            foreach ( $found as $size => $count ) {
                printf( '<tr><td><code>%s</code></td><td>%d</td></tr>', esc_html( $size ), (int) $count );
            }
            printf( '</tbody></table><p>%s</p>', esc_html( 'Space used by these files: ' . size_format( $bytes, 1 ) ) );
            echo '<form method="post" onsubmit="return confirm(\'Delete these resized files? Originals are kept.\');">';
            wp_nonce_field( 'wpide_unused_sizes' );
            submit_button( 'Delete unused size files in this batch', 'primary', 'wpide_delete_sizes' );
            echo '</form>';
        } elseif ( ! $delete ) {
            echo '<p>No unused size files in this batch.</p>';
        }
        if ( count( $ids ) === 300 && ! $delete ) {
            echo '<p><a class="button" href="' . esc_url( add_query_arg( 'offset', $offset + 300 ) ) . '">Check the next 300 images</a></p>';
        }
        echo '</div>';
    } );
} );