Extension to the Google XML Sitemaps plugin(version 4.0+) that lists all media attachments in the sitemap

gsmg-media.php

<?php 
/*
	Plugin Name: Google XML Sitemaps - Media support
	Description: This plugin will display all of your media in the automatically generated sitemap created by the Google XML Sitemaps plugin v 4.0+
	Version: 1
	Author: Nikola Nikolov
	Author URI: http://paiyakdev.com/
*/

if ( ! defined( 'ABSPATH' ) ) {
	return;
}

add_action( 'sm_build_index',   'gsmg_register_extension', 10 );
add_action( 'sm_build_content', 'gsmg_register_extension', 10 );

function gsmg_register_extension() {
	static $extension = null;

	if ( is_null( $extension ) && class_exists( 'GoogleSitemapGeneratorStandardBuilder' ) ) {
		/**
		* 
		*/
		class GSMG_Media extends GoogleSitemapGeneratorStandardBuilder {
			/**
			 * Override the default construct method for GoogleSitemapGeneratorStandardBuilder
			 *
			 * This way we add our actions with lower(higher index) priority,
			 * so that the media list comes last
			 */
			function __construct() {
				add_action( "sm_build_index", array( $this, "main" ), 15, 1 );
				add_action( "sm_build_content", array( $this, "render_attachments" ), 15, 3 );
			}

			public function main( $gsg ) {
				global $wpdb;

				$wpdb->show_errors();

				$q = "SELECT
						YEAR(p.post_date) AS `year`,
						MONTH(p.post_date) AS `month`,
						COUNT(p.ID) AS `numposts`,
						MAX(p.post_date) as `last_mod`
					FROM
						{$wpdb->posts} p
					WHERE
						p.post_password = ''
						AND p.post_type = 'attachment'
						AND p.post_status = 'inherit'
						AND (
							p.post_parent = 0 OR 'publish' = ( SELECT post_status FROM {$wpdb->posts} WHERE {$wpdb->posts}.post_parent=p.ID )
						)
					GROUP BY
						YEAR(p.post_date),
						MONTH(p.post_date)
					ORDER BY
						p.post_date DESC";

				$posts = $wpdb->get_results( $q );

				if ( $posts ) {
					foreach ( $posts as $post ) {
						$gsg->AddSitemap( "media", sprintf( "%04d-%02d", $post->year, $post->month ), $gsg->GetTimestampFromMySql( $post->last_mod ) );
					}
				}
			}

			public function render_attachments( $gsg, $type, $params ) {
				if ( 'media' == $type && preg_match( '/^([0-9]{4})\-([0-9]{2})$/', $params, $matches ) ) {
					$year = $matches[1];
					$month = $matches[2];

					//All comments as an asso. Array (postID=>commentCount)
					$comments = array();

					//Full number of comments
					$commentCount = 0;

					$qp = $this->BuildPostQuery( $gsg, 'attachment' );

					$qp['year'] = $year;
					$qp['monthnum'] = $month;

					//Don't retrieve and update meta values and taxonomy terms if they are not used in the permalink
					$struct = get_option('permalink_structure');
					if ( strpos( $struct, "%category%" ) === false && strpos( $struct, "%tag%" ) === false ) {
						$qp['update_post_term_cache'] = false;
					}

					$qp['update_post_meta_cache'] = false;

					//Add filter to remove password protected posts
					add_filter( 'posts_search', array( $this, 'FilterPassword' ), 10, 1 );

					//Add filter to filter the fields
					add_filter( 'posts_fields', array( $this, 'FilterFields' ), 10, 1 );

					$posts = get_posts( $qp );

					//Remove the filter again
					remove_filter( 'posts_where', array( $this, 'FilterPassword' ), 10, 1 );
					remove_filter( 'posts_fields', array( $this, 'FilterFields' ), 10, 1 );

					if ( $postCount = count( $posts ) > 0 ) {

						$prioProvider = NULL;

						if ( '' != $gsg->GetOption( "b_prio_provider" ) ) {
							$providerClass = $gsg->GetOption( 'b_prio_provider' );
							$prioProvider = new $providerClass( 0, $postCount );
						}

						//Default priorities
						$default_prio_posts = $gsg->GetOption( 'pr_posts' );

						//Change frequencies
						$cf_posts = $gsg->GetOption( 'cf_posts' );

						//Minimum priority
						$minPrio = $gsg->GetOption( 'pr_posts_min' );

						foreach ( $posts as $post ) {
							$permalink = get_permalink( $post->ID );
							$parent_status = 0 == $post->post_parent ? 'publish' : get_post_status( $post->post_parent );

							//Exclude the home page and placeholder items by some plugins...
							if ( ! empty( $permalink ) && $permalink != "#" && 'publish' == $parent_status ) {
								//Default Priority if auto calc is disabled
								$prio = $default_prio_posts;

								$time = $post->post_modified_gmt && $post->post_modified_gmt != '0000-00-00 00:00:00' ? $post->post_modified_gmt : $post->post_date_gmt;

								$gsg->AddUrl( $permalink, $gsg->GetTimestampFromMySql( $time ), $cf_posts, $prio, $post->ID );
							}
						}
					}
				}
			}
		}

		$extension = new GSMG_Media();
	}
}