Multisite Development

<?php
/**
 * Network-level features: site life cycle, network settings and network-wide statistics.
 *
 * @package Lumen\Catalog
 */

namespace Lumen\Catalog;

defined( 'ABSPATH' ) || exit;

/**
 * Booted from Plugin::boot() only when is_multisite() is true.
 */
final class Network {

	const SETTINGS = 'lp_catalog_network_settings'; // Network option (wp_sitemeta).
	const COUNTS   = 'lp_network_book_counts';      // Site transient, shared by the network.
	const IMPRINT  = 'lp_imprint';                  // Site meta key (wp_blogmeta).
	const PAGE     = 'lumen-catalog-network';       // Admin page slug and network/edit.php action.

	public static function boot(): void {
		add_action( 'wp_initialize_site', array( self::class, 'initialize_site' ), 900 );
		add_filter( 'wpmu_drop_tables', array( self::class, 'drop_tables' ), 10, 2 );
		add_action( 'wp_delete_site', array( self::class, 'flush_counts' ) );
		add_action( 'save_post_lp_book', array( self::class, 'flush_counts' ) );
		add_action( 'deleted_post', array( self::class, 'flush_counts' ), 10, 2 );
		add_action( 'network_admin_menu', array( self::class, 'add_menu' ) );
		add_action( 'network_admin_edit_' . self::PAGE, array( self::class, 'save_settings' ) );
	}

	public static function is_network_active(): bool {
		if ( ! function_exists( 'is_plugin_active_for_network' ) ) {
			require_once ABSPATH . 'wp-admin/includes/plugin.php'; // Admin-only file.
		}
		return is_plugin_active_for_network( plugin_basename( LUMEN_CATALOG_FILE ) );
	}

	// A new site gets its table and settings now; priority 900 runs after core (10) created its tables.
	public static function initialize_site( \WP_Site $site ): void {
		if ( ! self::is_network_active() ) {
			return;
		}
		$network = (array) get_site_option( self::SETTINGS, array() );

		switch_to_blog( $site->id );
		Installer::upgrade();
		delete_option( 'rewrite_rules' ); // Built while switched, with the main site's /blog/ front: rebuild on first request.
		if ( isset( $network['isbn_prefix'] ) ) {
			update_option( 'lp_catalog_settings', array( 'isbn_prefix' => $network['isbn_prefix'] ) );
		}
		restore_current_blog();
	}

	// Core drops only its own tables (DROP TABLE IF EXISTS); add every per-site table of the plugin.
	public static function drop_tables( array $tables, int $site_id ): array {
		global $wpdb;
		$prefix   = $wpdb->get_blog_prefix( $site_id );
		$tables[] = $prefix . 'lp_stock';
		$tables[] = $prefix . 'lp_loans'; // Schema version 3, added in REST API: Extending It.
		return $tables;
	}

	// Published books per imprint site, cached for the whole network for one hour.
	public static function book_counts(): array {
		$counts = get_site_transient( self::COUNTS );
		if ( is_array( $counts ) ) {
			return $counts;
		}

		$counts   = array();
		$site_ids = get_sites(
			array(
				'fields'   => 'ids',
				'meta_key' => self::IMPRINT, // phpcs:ignore WordPress.DB.SlowDBQuery.slow_db_query_meta_key -- wp_blogmeta is small.
				'archived' => 0,
				'spam'     => 0,
				'deleted'  => 0,
				'number'   => 500,
			)
		);
		foreach ( $site_ids as $site_id ) {
			switch_to_blog( $site_id );
			$by_status          = wp_count_posts( 'lp_book' );
			$counts[ $site_id ] = array(
				'imprint' => (string) get_site_meta( $site_id, self::IMPRINT, true ),
				'name'    => (string) get_option( 'blogname' ),
				'books'   => (int) ( $by_status->publish ?? 0 ),
			);
			restore_current_blog();
		}

		set_site_transient( self::COUNTS, $counts, HOUR_IN_SECONDS );
		return $counts;
	}

	// Drops the cached counts when a book or a site changes ($post is set on deleted_post).
	public static function flush_counts( $item = null, $post = null ): void {
		if ( $post instanceof \WP_Post && 'lp_book' !== $post->post_type ) {
			return;
		}
		delete_site_transient( self::COUNTS );
	}

	public static function add_menu(): void {
		add_submenu_page( 'settings.php', __( 'Lumen Catalog network settings', 'lumen-catalog' ), __( 'Lumen Catalog', 'lumen-catalog' ), 'manage_network_options', self::PAGE, array( self::class, 'render_page' ) );
	}

	public static function render_page(): void {
		$settings = (array) get_site_option( self::SETTINGS, array( 'isbn_prefix' => '978' ) );
		?>
		<div class="wrap">
			<h1><?php echo esc_html( get_admin_page_title() ); ?></h1>
			<?php if ( isset( $_GET['updated'] ) ) : // phpcs:ignore WordPress.Security.NonceVerification.Recommended ?>
				<div class="notice notice-success is-dismissible"><p><?php esc_html_e( 'Settings saved.', 'lumen-catalog' ); ?></p></div>
			<?php endif; ?>
			<form method="post" action="<?php echo esc_url( network_admin_url( 'edit.php?action=' . self::PAGE ) ); ?>">
				<?php wp_nonce_field( self::PAGE ); ?>
				<p><label for="lp-isbn-prefix"><?php esc_html_e( 'ISBN prefix for new imprints', 'lumen-catalog' ); ?></label>
				<input name="isbn_prefix" id="lp-isbn-prefix" type="text" class="small-text" value="<?php echo esc_attr( $settings['isbn_prefix'] ?? '978' ); ?>"></p>
				<?php submit_button(); ?>
			</form>
			<h2><?php esc_html_e( 'Published books per imprint', 'lumen-catalog' ); ?></h2>
			<table class="widefat striped">
				<?php foreach ( self::book_counts() as $row ) : ?>
					<tr><td><?php echo esc_html( $row['name'] ); ?></td><td><?php echo esc_html( number_format_i18n( $row['books'] ) ); ?></td></tr>
				<?php endforeach; ?>
			</table>
		</div>
		<?php
	}

	// Saves the form. network/edit.php checks only that the user is logged in.
	public static function save_settings(): void {
		if ( ! current_user_can( 'manage_network_options' ) ) {
			wp_die( esc_html__( 'Sorry, you are not allowed to manage options for this network.', 'lumen-catalog' ), 403 );
		}
		check_admin_referer( self::PAGE );

		$prefix = isset( $_POST['isbn_prefix'] ) ? sanitize_text_field( wp_unslash( $_POST['isbn_prefix'] ) ) : '978';
		update_site_option( self::SETTINGS, array( 'isbn_prefix' => in_array( $prefix, array( '978', '979' ), true ) ? $prefix : '978' ) );

		wp_safe_redirect( add_query_arg( array( 'page' => self::PAGE, 'updated' => 'true' ), network_admin_url( 'settings.php' ) ) );
		exit;
	}
}

$ wp eval 'foreach ( Lumen\Catalog\Network::book_counts() as $id => $row ) { printf( "%d  %-5s %-11s %d\n", $id, $row["imprint"], $row["name"], $row["books"] ); }'
2  kids  Lumen Kids  2
3  noir  Lumen Noir  3
$ wp transient get lp_network_book_counts --network --format=json
{"2":{"imprint":"kids","name":"Lumen Kids","books":2},"3":{"imprint":"noir","name":"Lumen Noir","books":3}}
$ wp post create --post_type=lp_book --post_status=publish --post_title="Owl Post" --url=lumenpress.test/kids/ --porcelain
5
$ wp transient get lp_network_book_counts --network
Warning: Transient with key "lp_network_book_counts" is not set.

$ wp site create --slug=classics --title="Lumen Classics" --email=admin@lumenpress.test --porcelain
4
$ wp db query "SHOW TABLES LIKE 'wp\_4\_lp%'" --skip-column-names
wp_4_lp_stock
$ wp site delete 4 --yes
Success: The site at 'http://lumenpress.test/classics/' was deleted.
$ wp db query "SHOW TABLES LIKE 'wp\_4\_%'" --skip-column-names | wc -l
0

GET  /wp-admin/network/settings.php?page=lumen-catalog-network (admin)
     200, <h1>Lumen Catalog network settings</h1>, rows "Lumen Kids 3" and "Lumen Noir 3"
POST /wp-admin/network/edit.php?action=lumen-catalog-network (admin, with _wpnonce, isbn_prefix=978)
     302 to /wp-admin/network/settings.php?page=lumen-catalog-network&updated=true
POST /wp-admin/network/edit.php?action=lumen-catalog-network (admin, no nonce)
     403, "The link you followed has expired."
POST /wp-admin/network/edit.php?action=lumen-catalog-network (maria.editor)
     403, "Sorry, you are not allowed to manage options for this network."
GET  /wp-admin/network/settings.php?page=lumen-catalog-network (maria.editor)
     403