al WP_Object_Cache $wp_object_cache
 *
 * @return bool True on success, false if we're already on the current blog.
 */
function restore_current_blog() {
	global $wpdb;

	if ( empty( $GLOBALS['_wp_switched_stack'] ) ) {
		return false;
	}

	$new_blog_id  = array_pop( $GLOBALS['_wp_switched_stack'] );
	$prev_blog_id = get_current_blog_id();

	if ( $new_blog_id == $prev_blog_id ) {
		/** This filter is documented in wp-includes/ms-blogs.php */
		do_action( 'switch_blog', $new_blog_id, $prev_blog_id, 'restore' );

		// If we still have items in the switched stack, consider ourselves still 'switched'.
		$GLOBALS['switched'] = ! empty( $GLOBALS['_wp_switched_stack'] );

		return true;
	}

	$wpdb->set_blog_id( $new_blog_id );
	$GLOBALS['blog_id']      = $new_blog_id;
	$GLOBALS['table_prefix'] = $wpdb->get_blog_prefix();

	if ( function_exists( 'wp_cache_switch_to_blog' ) ) {
		wp_cache_switch_to_blog( $new_blog_id );
	} else {
		global $wp_object_cache;

		if ( is_object( $wp_object_cache ) && isset( $wp_object_cache->global_groups ) ) {
			$global_groups = $wp_object_cache->global_groups;
		} else {
			$global_groups = false;
		}

		wp_cache_init();

		if ( function_exists( 'wp_cache_add_global_groups' ) ) {
			if ( is_array( $global_groups ) ) {
				wp_cache_add_global_groups( $global_groups );
			} else {
				wp_cache_add_global_groups(
					array(
						'blog-details',
						'blog-id-cache',
						'blog-lookup',
						'blog_meta',
						'global-posts',
						'networks',
						'network-queries',
						'sites',
						'site-details',
						'site-options',
						'site-queries',
						'site-transient',
						'theme_files',
						'rss',
						'users',
						'user-queries',
						'user_meta',
						'useremail',
						'userlogins',
						'userslugs',
					)
				);
			}

			wp_cache_add_non_persistent_groups( array( 'counts', 'plugins', 'theme_json' ) );
		}
	}

	/** This filter is documented in wp-includes/ms-blogs.php */
	do_action( 'switch_blog', $new_blog_id, $prev_blog_id, 'restore' );

	// If we still have items in the switched stack, consider ourselves still 'switched'.
	$GLOBALS['switched'] = ! empty( $GLOBALS['_wp_switched_stack'] );

	return true;
}

/**
 * Switches the initialized roles and current user capabilities to another site.
 *
 * @since 4.9.0
 *
 * @param int $new_site_id New site ID.
 * @param int $old_site_id Old site ID.
 */
function wp_switch_roles_and_user( $new_site_id, $old_site_id ) {
	if ( $new_site_id == $old_site_id ) {
		return;
	}

	if ( ! did_action( 'init' ) ) {
		return;
	}

	wp_roles()->for_site( $new_site_id );
	wp_get_current_user()->for_site( $new_site_id );
}

/**
 * Determines if switch_to_blog() is in effect.
 *
 * @since 3.5.0
 *
 * @global array $_wp_switched_stack
 *
 * @return bool True if switched, false otherwise.
 */
function ms_is_switched() {
	return ! empty( $GLOBALS['_wp_switched_stack'] );
}

/**
 * Checks if a particular blog is archived.
 *
 * @since MU (3.0.0)
 *
 * @param int $id Blog ID.
 * @return string Whether the blog is archived or not.
 */
function is_archived( $id ) {
	return get_blog_status( $id, 'archived' );
}

/**
 * Updates the 'archived' status of a particular blog.
 *
 * @since MU (3.0.0)
 *
 * @param int    $id       Blog ID.
 * @param string $archived The new status.
 * @return string $archived
 */
function update_archived( $id, $archived ) {
	update_blog_status( $id, 'archived', $archived );
	return $archived;
}

/**
 * Updates a blog details field.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 Use wp_update_site() internally.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int    $blog_id    Blog ID.
 * @param string $pref       Field name.
 * @param string $value      Field value.
 * @param null   $deprecated Not used.
 * @return string|false $value
 */
function update_blog_status( $blog_id, $pref, $value, $deprecated = null ) {
	global $wpdb;

	if ( null !== $deprecated ) {
		_deprecated_argument( __FUNCTION__, '3.1.0' );
	}

	$allowed_field_names = array( 'site_id', 'domain', 'path', 'registered', 'last_updated', 'public', 'archived', 'mature', 'spam', 'deleted', 'lang_id' );

	if ( ! in_array( $pref, $allowed_field_names, true ) ) {
		return $value;
	}

	$result = wp_update_site(
		$blog_id,
		array(
			$pref => $value,
		)
	);

	if ( is_wp_error( $result ) ) {
		return false;
	}

	return $value;
}

/**
 * Gets a blog details field.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int    $id   Blog ID.
 * @param string $pref Field name.
 * @return bool|string|null $value
 */
function get_blog_status( $id, $pref ) {
	global $wpdb;

	$details = get_site( $id );
	if ( $details ) {
		return $details->$pref;
	}

	return $wpdb->get_var( $wpdb->prepare( "SELECT %s FROM {$wpdb->blogs} WHERE blog_id = %d", $pref, $id ) );
}

/**
 * Gets a list of most recently updated blogs.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param mixed $deprecated Not used.
 * @param int   $start      Optional. Number of blogs to offset the query. Used to build LIMIT clause.
 *                          Can be used for pagination. Default 0.
 * @param int   $quantity   Optional. The maximum number of blogs to retrieve. Default 40.
 * @return array The list of blogs.
 */
function get_last_updated( $deprecated = '', $start = 0, $quantity = 40 ) {
	global $wpdb;

	if ( ! empty( $deprecated ) ) {
		_deprecated_argument( __FUNCTION__, 'MU' ); // Never used.
	}

	return $wpdb->get_results( $wpdb->prepare( "SELECT blog_id, domain, path FROM $wpdb->blogs WHERE site_id = %d AND public = '1' AND archived = '0' AND mature = '0' AND spam = '0' AND deleted = '0' AND last_updated != '0000-00-00 00:00:00' ORDER BY last_updated DESC limit %d, %d", get_current_network_id(), $start, $quantity ), ARRAY_A );
}

/**
 * Handler for updating the site's last updated date when a post is published or
 * an already published post is changed.
 *
 * @since 3.3.0
 *
 * @param string  $new_status The new post status.
 * @param string  $old_status The old post status.
 * @param WP_Post $post       Post object.
 */
function _update_blog_date_on_post_publish( $new_status, $old_status, $post ) {
	$post_type_obj = get_post_type_object( $post->post_type );
	if ( ! $post_type_obj || ! $post_type_obj->public ) {
		return;
	}

	if ( 'publish' !== $new_status && 'publish' !== $old_status ) {
		return;
	}

	// Post was freshly published, published post was saved, or published post was unpublished.

	wpmu_update_blogs_date();
}

/**
 * Handler for updating the current site's last updated date when a published
 * post is deleted.
 *
 * @since 3.4.0
 *
 * @param int $post_id Post ID
 */
function _update_blog_date_on_post_delete( $post_id ) {
	$post = get_post( $post_id );

	$post_type_obj = get_post_type_object( $post->post_type );
	if ( ! $post_type_obj || ! $post_type_obj->public ) {
		return;
	}

	if ( 'publish' !== $post->post_status ) {
		return;
	}

	wpmu_update_blogs_date();
}

/**
 * Handler for updating the current site's posts count when a post is deleted.
 *
 * @since 4.0.0
 * @since 6.2.0 Added the `$post` parameter.
 *
 * @param int     $post_id Post ID.
 * @param WP_Post $post    Post object.
 */
function _update_posts_count_on_delete( $post_id, $post ) {
	if ( ! $post || 'publish' !== $post->post_status || 'post' !== $post->post_type ) {
		return;
	}

	update_posts_count();
}

/**
 * Handler for updating the current site's posts count when a post status changes.
 *
 * @since 4.0.0
 * @since 4.9.0 Added the `$post` parameter.
 *
 * @param string  $new_status The status the post is changing to.
 * @param string  $old_status The status the post is changing from.
 * @param WP_Post $post       Post object
 */
function _update_posts_count_on_transition_post_status( $new_status, $old_status, $post = null ) {
	if ( $new_status === $old_status ) {
		return;
	}

	if ( 'post' !== get_post_type( $post ) ) {
		return;
	}

	if ( 'publish' !== $new_status && 'publish' !== $old_status ) {
		return;
	}

	update_posts_count();
}

/**
 * Counts number of sites grouped by site status.
 *
 * @since 5.3.0
 *
 * @param int $network_id Optional. The network to get counts for. Default is the current network ID.
 * @return int[] {
 *     Numbers of sites grouped by site status.
 *
 *     @type int $all      The total number of sites.
 *     @type int $public   The number of public sites.
 *     @type int $archived The number of archived sites.
 *     @type int $mature   The number of mature sites.
 *     @type int $spam     The number of spam sites.
 *     @type int $deleted  The number of deleted sites.
 * }
 */
function wp_count_sites( $network_id = null ) {
	if ( empty( $network_id ) ) {
		$network_id = get_current_network_id();
	}

	$counts = array();
	$args   = array(
		'network_id'    => $network_id,
		'number'        => 1,
		'fields'        => 'ids',
		'no_found_rows' => false,
	);

	$q             = new WP_Site_Query( $args );
	$counts['all'] = $q->found_sites;

	$_args    = $args;
	$statuses = array( 'public', 'archived', 'mature', 'spam', 'deleted' );

	foreach ( $statuses as $status ) {
		$_args            = $args;
		$_args[ $status ] = 1;

		$q                 = new WP_Site_Query( $_args );
		$counts[ $status ] = $q->found_sites;
	}

	return $counts;
}