ail );

	$admin_email = get_site_option( 'admin_email' );

	if ( '' === $admin_email ) {
		$admin_email = 'support@' . wp_parse_url( network_home_url(), PHP_URL_HOST );
	}

	$from_name       = ( '' !== get_site_option( 'site_name' ) ) ? esc_html( get_site_option( 'site_name' ) ) : 'WordPress';
	$message_headers = "From: \"{$from_name}\" <{$admin_email}>\n" . 'Content-Type: text/plain; charset="' . get_option( 'blog_charset' ) . "\"\n";
	$message         = $welcome_email;

	if ( empty( $current_network->site_name ) ) {
		$current_network->site_name = 'WordPress';
	}

	/* translators: New user notification email subject. 1: Network title, 2: New user login. */
	$subject = __( 'New %1$s User: %2$s' );

	/**
	 * Filters the subject of the welcome email after user activation.
	 *
	 * @since MU (3.0.0)
	 *
	 * @param string $subject Subject of the email.
	 */
	$subject = apply_filters( 'update_welcome_user_subject', sprintf( $subject, $current_network->site_name, $user->user_login ) );

	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );

	if ( $switched_locale ) {
		restore_previous_locale();
	}

	return true;
}

/**
 * Gets the current network.
 *
 * Returns an object containing the 'id', 'domain', 'path', and 'site_name'
 * properties of the network being viewed.
 *
 * @see wpmu_current_site()
 *
 * @since MU (3.0.0)
 *
 * @global WP_Network $current_site The current network.
 *
 * @return WP_Network The current network.
 */
function get_current_site() {
	global $current_site;
	return $current_site;
}

/**
 * Gets a user's most recent post.
 *
 * Walks through each of a user's blogs to find the post with
 * the most recent post_date_gmt.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param int $user_id User ID.
 * @return array Contains the blog_id, post_id, post_date_gmt, and post_gmt_ts.
 */
function get_most_recent_post_of_user( $user_id ) {
	global $wpdb;

	$user_blogs       = get_blogs_of_user( (int) $user_id );
	$most_recent_post = array();

	/*
	 * Walk through each blog and get the most recent post
	 * published by $user_id.
	 */
	foreach ( (array) $user_blogs as $blog ) {
		$prefix      = $wpdb->get_blog_prefix( $blog->userblog_id );
		$recent_post = $wpdb->get_row( $wpdb->prepare( "SELECT ID, post_date_gmt FROM {$prefix}posts WHERE post_author = %d AND post_type = 'post' AND post_status = 'publish' ORDER BY post_date_gmt DESC LIMIT 1", $user_id ), ARRAY_A );

		// Make sure we found a post.
		if ( isset( $recent_post['ID'] ) ) {
			$post_gmt_ts = strtotime( $recent_post['post_date_gmt'] );

			/*
			 * If this is the first post checked
			 * or if this post is newer than the current recent post,
			 * make it the new most recent post.
			 */
			if ( ! isset( $most_recent_post['post_gmt_ts'] ) || ( $post_gmt_ts > $most_recent_post['post_gmt_ts'] ) ) {
				$most_recent_post = array(
					'blog_id'       => $blog->userblog_id,
					'post_id'       => $recent_post['ID'],
					'post_date_gmt' => $recent_post['post_date_gmt'],
					'post_gmt_ts'   => $post_gmt_ts,
				);
			}
		}
	}

	return $most_recent_post;
}

//
// Misc functions.
//

/**
 * Checks an array of MIME types against a list of allowed types.
 *
 * WordPress ships with a set of allowed upload filetypes,
 * which is defined in wp-includes/functions.php in
 * get_allowed_mime_types(). This function is used to filter
 * that list against the filetypes allowed provided by Multisite
 * Super Admins at wp-admin/network/settings.php.
 *
 * @since MU (3.0.0)
 *
 * @param array $mimes
 * @return array
 */
function check_upload_mimes( $mimes ) {
	$site_exts  = explode( ' ', get_site_option( 'upload_filetypes', 'jpg jpeg png gif' ) );
	$site_mimes = array();
	foreach ( $site_exts as $ext ) {
		foreach ( $mimes as $ext_pattern => $mime ) {
			if ( '' !== $ext && str_contains( $ext_pattern, $ext ) ) {
				$site_mimes[ $ext_pattern ] = $mime;
			}
		}
	}
	return $site_mimes;
}

/**
 * Updates a blog's post count.
 *
 * WordPress MS stores a blog's post count as an option so as
 * to avoid extraneous COUNTs when a blog's details are fetched
 * with get_site(). This function is called when posts are published
 * or unpublished to make sure the count stays current.
 *
 * @since MU (3.0.0)
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $deprecated Not used.
 */
function update_posts_count( $deprecated = '' ) {
	global $wpdb;
	update_option( 'post_count', (int) $wpdb->get_var( "SELECT COUNT(ID) FROM {$wpdb->posts} WHERE post_status = 'publish' and post_type = 'post'" ) );
}

/**
 * Logs the user email, IP, and registration date of a new site.
 *
 * @since MU (3.0.0)
 * @since 5.1.0 Parameters now support input from the {@see 'wp_initialize_site'} action.
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param WP_Site|int $blog_id The new site's object or ID.
 * @param int|array   $user_id User ID, or array of arguments including 'user_id'.
 */
function wpmu_log_new_registrations( $blog_id, $user_id ) {
	global $wpdb;

	if ( is_object( $blog_id ) ) {
		$blog_id = $blog_id->blog_id;
	}

	if ( is_array( $user_id ) ) {
		$user_id = ! empty( $user_id['user_id'] ) ? $user_id['user_id'] : 0;
	}

	$user = get_userdata( (int) $user_id );
	if ( $user ) {
		$wpdb->insert(
			$wpdb->registration_log,
			array(
				'email'           => $user->user_email,
				'IP'              => preg_replace( '/[^0-9., ]/', '', wp_unslash( $_SERVER['REMOTE_ADDR'] ) ),
				'blog_id'         => $blog_id,
				'date_registered' => current_time( 'mysql' ),
			)
		);
	}
}

/**
 * Ensures that the current site's domain is listed in the allowed redirect host list.
 *
 * @see wp_validate_redirect()
 * @since MU (3.0.0)
 *
 * @param array|string $deprecated Not used.
 * @return string[] {
 *     An array containing the current site's domain.
 *
 *     @type string $0 The current site's domain.
 * }
 */
function redirect_this_site( $deprecated = '' ) {
	return array( get_network()->domain );
}

/**
 * Checks whether an upload is too big.
 *
 * @since MU (3.0.0)
 *
 * @param array $upload An array of information about the newly-uploaded file.
 * @return string|array If the upload is under the size limit, $upload is returned. Otherwise returns an error message.
 */
function upload_is_file_too_big( $upload ) {
	if ( ! is_array( $upload ) || defined( 'WP_IMPORTING' ) || get_site_option( 'upload_space_check_disabled' ) ) {
		return $upload;
	}

	if ( strlen( $upload['bits'] ) > ( KB_IN_BYTES * get_site_option( 'fileupload_maxk', 1500 ) ) ) {
		/* translators: %s: Maximum allowed file size in kilobytes. */
		return sprintf( __( 'This file is too big. Files must be less than %s KB in size.' ) . '<br />', get_site_option( 'fileupload_maxk', 1500 ) );
	}

	return $upload;
}

/**
 * Adds a nonce field to the signup page.
 *
 * @since MU (3.0.0)
 */
function signup_nonce_fields() {
	$id = mt_rand();
	echo "<input type='hidden' name='signup_form_id' value='{$id}' />";
	wp_nonce_field( 'signup_form_' . $id, '_signup_form', false );
}

/**
 * Processes the signup nonce created in signup_nonce_fields().
 *
 * @since MU (3.0.0)
 *
 * @param array $result
 * @return array
 */
function signup_nonce_check( $result ) {
	if ( ! strpos( $_SERVER['PHP_SELF'], 'wp-signup.php' ) ) {
		return $result;
	}

	if ( ! wp_verify_nonce( $_POST['_signup_form'], 'signup_form_' . $_POST['signup_form_id'] ) ) {
		$result['errors']->add( 'invalid_nonce', __( 'Unable to submit this form, please try again.' ) );
	}

	return $result;
}

/**
 * Corrects 404 redirects when NOBLOGREDIRECT is defined.
 *
 * @since MU (3.0.0)
 */
function maybe_redirect_404() {
	if ( is_main_site() && is_404() && defined( 'NOBLOGREDIRECT' ) ) {
		/**
		 * Filters the redirect URL for 404s on the main site.
		 *
		 * The filter is only evaluated if the NOBLOGREDIRECT constant is defined.
		 *
		 * @since 3.0.0
		 *
		 * @param string $no_blog_redirect The redirect URL defined in NOBLOGREDIRECT.
		 */
		$destination = apply_filters( 'blog_redirect_404', NOBLOGREDIRECT );

		if ( $destination ) {
			if ( '%siteurl%' === $destination ) {
				$destination = network_home_url();
			}

			wp_redirect( $destination );
			exit;
		}
	}
}

/**
 * Adds a new user to a blog by visiting /newbloguser/{key}/.
 *
 * This will only work when the user's details are saved as an option
 * keyed as 'new_user_{key}', where '{key}' is a hash generated for the user to be
 * added, as when a user is invited through the regular WP Add User interface.
 *
 * @since MU (3.0.0)
 */
function maybe_add_existing_user_to_blog() {
	if ( ! str_contains( $_SERVER['REQUEST_URI'], '/newbloguser/' ) ) {
		return;
	}

	$parts = explode( '/', $_SERVER['REQUEST_URI'] );
	$key   = array_pop( $parts );

	if ( '' === $key ) {
		$key = array_pop( $parts );
	}

	$details = get_option( 'new_user_' . $key );
	if ( ! empty( $details ) ) {
		delete_option( 'new_user_' . $key );
	}

	if ( empty( $details ) || is_wp_error( add_existing_user_to_blog( $details ) ) ) {
		wp_die(
			sprintf(
				/* translators: %s: Home URL. */
				__( 'An error occurred adding you to this site. Go to the <a href="%s">homepage</a>.' ),
				home_url()
			)
		);
	}

	wp_die(
		sprintf(
			/* translators: 1: Home URL, 2: Admin URL. */
			__( 'You have been added to this site. Please visit the <a href="%1$s">homepage</a> or <a href="%2$s">log in</a> using your username and password.' ),
			home_url(),
			admin_url()
		),
		__( 'WordPress &rsaquo; Success' ),
		array( 'response' => 200 )
	);
}

/**
 * Adds a user to a blog based on details from maybe_add_existing_user_to_blog().
 *
 * @since MU (3.0.0)
 *
 * @param array|false $details {
 *     User details. Must at least contain values for the keys listed below.
 *
 *     @type int    $user_id The ID of the user being added to the current blog.
 *     @type string $role    The role to be assigned to the user.
 * }
 * @return true|WP_Error|void True on success or a WP_Error object if the user doesn't exist
 *                            or could not be added. Void if $details array was not provided.
 */
function add_existing_user_to_blog( $details = false ) {
	if ( is_array( $details ) ) {
		$blog_id = get_current_blog_id();
		$result  = add_user_to_blog( $blog_id, $details['user_id'], $details['role'] );

		/**
		 * Fires immediately after an existing user is added to a site.
		 *
		 * @since MU (3.0.0)
		 *
		 * @param int           $user_id User ID.
		 * @param true|WP_Error $result  True on success or a WP_Error object if the user doesn't exist
		 *                               or could not be added.
		 */
		do_action( 'added_existing_user', $details['user_id'], $result );

		return $result;
	}
}

/**
 * Adds a newly created user to the appropriate blog
 *
 * To add a user in general, use add_user_to_blog(). This function
 * is specifically hooked into the {@see 'wpmu_activate_user'} action.
 *
 * @since MU (3.0.0)
 *
 * @see add_user_to_blog()
 *
 * @param int    $user_id  User ID.
 * @param string $password User password. Ignored.
 * @param array  $meta     Signup meta data.
 */
function add_new_user_to_blog( $user_id, $password, $meta ) {
	if ( ! empty( $meta['add_to_blog'] ) ) {
		$blog_id = $meta['add_to_blog'];
		$role    = $meta['new_role'];
		remove_user_from_blog( $user_id, get_network()->site_id ); // Remove user from main blog.

		$result = add_user_to_blog( $blog_id, $user_id, $role );

		if ( ! is_wp_error( $result ) ) {
			update_user_meta( $user_id, 'primary_blog', $blog_id );
		}
	}
}

/**
 * Corrects From host on outgoing mail to match the site domain.
 *
 * @since MU (3.0.0)
 *
 * @param PHPMailer $phpmailer The PHPMailer instance (passed by reference).
 */
function fix_phpmailer_messageid( $phpmailer ) {
	$phpmailer->Hostname = get_network()->domain;
}

/**
 * Determines whether a user is marked as a spammer, based on user login.
 *
 * @since MU (3.0.0)
 *
 * @param string|WP_User $user Optional. Defaults to current user. WP_User object,
 *                             or user login name as a string.
 * @return bool
 */
function is_user_spammy( $user = null ) {
	if ( ! ( $user instanceof WP_User ) ) {
		if ( $user ) {
			$user = get_user_by( 'login', $user );
		} else {
			$user = wp_get_current_user();
		}
	}

	return $user && isset( $user->spam ) && 1 == $user->spam;
}

/**
 * Updates this blog's 'public' setting in the global blogs table.
 *
 * Public blogs have a setting of 1, private blogs are 0.
 *
 * @since MU (3.0.0)
 *
 * @param int $old_value The old public value.
 * @param int $value     The new public value.
 */
function update_blog_public( $old_value, $value ) {
	update_blog_status( get_current_blog_id(), 'public', (int) $value );
}

/**
 * Determines whether users can self-register, based on Network settings.
 *
 * @since MU (3.0.0)
 *
 * @return bool
 */
function users_can_register_signup_filter() {
	$registration = get_site_option( 'registration' );
	return ( 'all' === $registration || 'user' === $registration );
}

/**
 * Ensures that the welcome message is not empty. Currently unused.
 *
 * @since MU (3.0.0)
 *
 * @param string $text
 * @return string
 */
function welcome_user_msg_filter( $text ) {
	if ( ! $text ) {
		remove_filter( 'site_option_welcome_user_email', 'welcome_user_msg_filter' );

		/* translators: Do not translate USERNAME, PASSWORD, LOGINLINK, SITE_NAME: those are placeholders. */
		$text = __(
			'Howdy USERNAME,

Your new account is set up.

You can log in with the following information:
Username: USERNAME
Password: PASSWORD
LOGINLINK

Thanks!

--The Team @ SITE_NAME'
		);
		update_site_option( 'welcome_user_email', $text );
	}
	return $text;
}

/**
 * Determines whether to force SSL on content.
 *
 * @since 2.8.5
 *
 * @param bool $force
 * @return bool True if forced, false if not forced.
 */
function force_ssl_content( $force = '' ) {
	static $forced_content = false;

	if ( ! $force ) {
		$old_forced     = $forced_content;
		$forced_content = $force;
		return $old_forced;
	}

	return $forced_content;
}

/**
 * Formats a URL to use https.
 *
 * Useful as a filter.
 *
 * @since 2.8.5
 *
 * @param string $url URL.
 * @return string URL with https as the scheme.
 */
function filter_SSL( $url ) {  // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid
	if ( ! is_string( $url ) ) {
		return get_bloginfo( 'url' ); // Return home site URL with proper scheme.
	}

	if ( force_ssl_content() && is_ssl() ) {
		$url = set_url_scheme( $url, 'https' );
	}

	return $url;
}

/**
 * Schedules update of the network-wide counts for the current network.
 *
 * @since 3.1.0
 */
function wp_schedule_update_network_counts() {
	if ( ! is_main_site() ) {
		return;
	}

	if ( ! wp_next_scheduled( 'update_network_counts' ) && ! wp_installing() ) {
		wp_schedule_event( time(), 'twicedaily', 'update_network_counts' );
	}
}

/**
 * Updates the network-wide counts for the current network.
 *
 * @since 3.1.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_counts( $network_id = null ) {
	wp_update_network_user_counts( $network_id );
	wp_update_network_site_counts( $network_id );
}

/**
 * Updates the count of sites for the current network.
 *
 * If enabled through the {@see 'enable_live_network_counts'} filter, update the sites count
 * on a network when a site is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_site_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( 'sites', $network_id );

	/**
	 * Filters whether to update network site or user counts when a new site is created.
	 *
	 * @since 3.7.0
	 *
	 * @see wp_is_large_network()
	 *
	 * @param bool   $small_network Whether the network is considered small.
	 * @param string $context       Context. Either 'users' or 'sites'.
	 */
	if ( ! apply_filters( 'enable_live_network_counts', $is_small_network, 'sites' ) ) {
		return;
	}

	wp_update_network_site_counts( $network_id );
}

/**
 * Updates the network-wide users count.
 *
 * If enabled through the {@see 'enable_live_network_counts'} filter, update the users count
 * on a network when a user is created or its status is updated.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_maybe_update_network_user_counts( $network_id = null ) {
	$is_small_network = ! wp_is_large_network( 'users', $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	if ( ! apply_filters( 'enable_live_network_counts', $is_small_network, 'users' ) ) {
		return;
	}

	wp_update_network_user_counts( $network_id );
}

/**
 * Updates the network-wide site count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_site_counts( $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	$count = get_sites(
		array(
			'network_id'             => $network_id,
			'spam'                   => 0,
			'deleted'                => 0,
			'archived'               => 0,
			'count'                  => true,
			'update_site_meta_cache' => false,
		)
	);

	update_network_option( $network_id, 'blog_count', $count );
}

/**
 * Updates the network-wide user count.
 *
 * @since 3.7.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 * @since 6.0.0 This function is now a wrapper for wp_update_user_counts().
 *
 * @param int|null $network_id ID of the network. Default is the current network.
 */
function wp_update_network_user_counts( $network_id = null ) {
	wp_update_user_counts( $network_id );
}

/**
 * Returns the space used by the current site.
 *
 * @since 3.5.0
 *
 * @return int Used space in megabytes.
 */
function get_space_used() {
	/**
	 * Filters the amount of storage space used by the current site, in megabytes.
	 *
	 * @since 3.5.0
	 *
	 * @param int|false $space_used The amount of used space, in megabytes. Default false.
	 */
	$space_used = apply_filters( 'pre_get_space_used', false );

	if ( false === $space_used ) {
		$upload_dir = wp_upload_dir();
		$space_used = get_dirsize( $upload_dir['basedir'] ) / MB_IN_BYTES;
	}

	return $space_used;
}

/**
 * Returns the upload quota for the current blog.
 *
 * @since MU (3.0.0)
 *
 * @return int Quota in megabytes.
 */
function get_space_allowed() {
	$space_allowed = get_option( 'blog_upload_space' );

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = get_site_option( 'blog_upload_space' );
	}

	if ( ! is_numeric( $space_allowed ) ) {
		$space_allowed = 100;
	}

	/**
	 * Filters the upload quota for the current site.
	 *
	 * @since 3.7.0
	 *
	 * @param int $space_allowed Upload quota in megabytes for the current blog.
	 */
	return apply_filters( 'get_space_allowed', $space_allowed );
}

/**
 * Determines if there is any upload space left in the current blog's quota.
 *
 * @since 3.0.0
 *
 * @return int of upload space available in bytes.
 */
function get_upload_space_available() {
	$allowed = get_space_allowed();
	if ( $allowed < 0 ) {
		$allowed = 0;
	}
	$space_allowed = $allowed * MB_IN_BYTES;
	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return $space_allowed;
	}

	$space_used = get_space_used() * MB_IN_BYTES;

	if ( ( $space_allowed - $space_used ) <= 0 ) {
		return 0;
	}

	return $space_allowed - $space_used;
}

/**
 * Determines if there is any upload space left in the current blog's quota.
 *
 * @since 3.0.0
 * @return bool True if space is available, false otherwise.
 */
function is_upload_space_available() {
	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return true;
	}

	return (bool) get_upload_space_available();
}

/**
 * Filters the maximum upload file size allowed, in bytes.
 *
 * @since 3.0.0
 *
 * @param int $size Upload size limit in bytes.
 * @return int Upload size limit in bytes.
 */
function upload_size_limit_filter( $size ) {
	$fileupload_maxk         = (int) get_site_option( 'fileupload_maxk', 1500 );
	$max_fileupload_in_bytes = KB_IN_BYTES * $fileupload_maxk;

	if ( get_site_option( 'upload_space_check_disabled' ) ) {
		return min( $size, $max_fileupload_in_bytes );
	}

	return min( $size, $max_fileupload_in_bytes, get_upload_space_available() );
}

/**
 * Determines whether or not we have a large network.
 *
 * The default criteria for a large network is either more than 10,000 users or more than 10,000 sites.
 * Plugins can alter this criteria using the {@see 'wp_is_large_network'} filter.
 *
 * @since 3.3.0
 * @since 4.8.0 The `$network_id` parameter has been added.
 *
 * @param string   $using      'sites' or 'users'. Default is 'sites'.
 * @param int|null $network_id ID of the network. Default is the current network.
 * @return bool True if the network meets the criteria for large. False otherwise.
 */
function wp_is_large_network( $using = 'sites', $network_id = null ) {
	$network_id = (int) $network_id;
	if ( ! $network_id ) {
		$network_id = get_current_network_id();
	}

	if ( 'users' === $using ) {
		$count = get_user_count( $network_id );

		$is_large_network = wp_is_large_user_count( $network_id );

		/**
		 * Filters whether the network is considered large.
		 *
		 * @since 3.3.0
		 * @since 4.8.0 The `$network_id` parameter has been added.
		 *
		 * @param bool   $is_large_network Whether the network has more than 10000 users or sites.
		 * @param string $component        The component to count. Accepts 'users', or 'sites'.
		 * @param int    $count            The count of items for the component.
		 * @param int    $network_id       The ID of the network being checked.
		 */
		return apply_filters( 'wp_is_large_network', $is_large_network, 'users', $count, $network_id );
	}

	$count = get_blog_count( $network_id );

	/** This filter is documented in wp-includes/ms-functions.php */
	return apply_filters( 'wp_is_large_network', $count > 10000, 'sites', $count, $network_id );
}

/**
 * Retrieves a list of reserved site on a sub-directory Multisite installation.
 *
 * @since 4.4.0
 *
 * @return string[] Array of reserved names.
 */
function get_subdirectory_reserved_names() {
	$names = array(
		'page',
		'comments',
		'blog',
		'files',
		'feed',
		'wp-admin',
		'wp-content',
		'wp-includes',
		'wp-json',
		'embed',
	);

	/**
	 * Filters reserved site names on a sub-directory Multisite installation.
	 *
	 * @since 3.0.0
	 * @since 4.4.0 'wp-admin', 'wp-content', 'wp-includes', 'wp-json', and 'embed' were added
	 *              to the reserved names list.
	 *
	 * @param string[] $subdirectory_reserved_names Array of reserved names.
	 */
	return apply_filters( 'subdirectory_reserved_names', $names );
}

/**
 * Sends a confirmation request email when a change of network admin email address is attempted.
 *
 * The new network admin address will not become active until confirmed.
 *
 * @since 4.9.0
 *
 * @param string $old_value The old network admin email address.
 * @param string $value     The proposed new network admin email address.
 */
function update_network_option_new_admin_email( $old_value, $value ) {
	if ( get_site_option( 'admin_email' ) === $value || ! is_email( $value ) ) {
		return;
	}

	$hash            = md5( $value . time() . mt_rand() );
	$new_admin_email = array(
		'hash'     => $hash,
		'newemail' => $value,
	);
	update_site_option( 'network_admin_hash', $new_admin_email );

	$switched_locale = switch_to_user_locale( get_current_user_id() );

	/* translators: Do not translate USERNAME, ADMIN_URL, EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_text = __(
		'Howdy ###USERNAME###,

You recently requested to have the network admin email address on
your network changed.

If this is correct, please click on the following link to change it:
###ADMIN_URL###

You can safely ignore and delete this email if you do not want to
take this action.

This email has been sent to ###EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###'
	);

	/**
	 * Filters the text of the email sent when a change of network admin email address is attempted.
	 *
	 * The following strings have a special meaning and will get replaced dynamically:
	 * ###USERNAME###  The current user's username.
	 * ###ADMIN_URL### The link to click on to confirm the email change.
	 * ###EMAIL###     The proposed new network admin email address.
	 * ###SITENAME###  The name of the network.
	 * ###SITEURL###   The URL to the network.
	 *
	 * @since 4.9.0
	 *
	 * @param string $email_text      Text in the email.
	 * @param array  $new_admin_email {
	 *     Data relating to the new network admin email address.
	 *
	 *     @type string $hash     The secure hash used in the confirmation link URL.
	 *     @type string $newemail The proposed new network admin email address.
	 * }
	 */
	$content = apply_filters( 'new_network_admin_email_content', $email_text, $new_admin_email );

	$current_user = wp_get_current_user();
	$content      = str_replace( '###USERNAME###', $current_user->user_login, $content );
	$content      = str_replace( '###ADMIN_URL###', esc_url( network_admin_url( 'settings.php?network_admin_hash=' . $hash ) ), $content );
	$content      = str_replace( '###EMAIL###', $value, $content );
	$content      = str_replace( '###SITENAME###', wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES ), $content );
	$content      = str_replace( '###SITEURL###', network_home_url(), $content );

	wp_mail(
		$value,
		sprintf(
			/* translators: Email change notification email subject. %s: Network title. */
			__( '[%s] Network Admin Email Change Request' ),
			wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES )
		),
		$content
	);

	if ( $switched_locale ) {
		restore_previous_locale();
	}
}

/**
 * Sends an email to the old network admin email address when the network admin email address changes.
 *
 * @since 4.9.0
 *
 * @param string $option_name The relevant database option name.
 * @param string $new_email   The new network admin email address.
 * @param string $old_email   The old network admin email address.
 * @param int    $network_id  ID of the network.
 */
function wp_network_admin_email_change_notification( $option_name, $new_email, $old_email, $network_id ) {
	$send = true;

	// Don't send the notification to the default 'admin_email' value.
	if ( 'you@example.com' === $old_email ) {
		$send = false;
	}

	/**
	 * Filters whether to send the network admin email change notification email.
	 *
	 * @since 4.9.0
	 *
	 * @param bool   $send       Whether to send the email notification.
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$send = apply_filters( 'send_network_admin_email_change_email', $send, $old_email, $new_email, $network_id );

	if ( ! $send ) {
		return;
	}

	/* translators: Do not translate OLD_EMAIL, NEW_EMAIL, SITENAME, SITEURL: those are placeholders. */
	$email_change_text = __(
		'Hi,

This notice confirms that the network admin email address was changed on ###SITENAME###.

The new network admin email address is ###NEW_EMAIL###.

This email has been sent to ###OLD_EMAIL###

Regards,
All at ###SITENAME###
###SITEURL###'
	);

	$email_change_email = array(
		'to'      => $old_email,
		/* translators: Network admin email change notification email subject. %s: Network title. */
		'subject' => __( '[%s] Network Admin Email Changed' ),
		'message' => $email_change_text,
		'headers' => '',
	);
	// Get network name.
	$network_name = wp_specialchars_decode( get_site_option( 'site_name' ), ENT_QUOTES );

	/**
	 * Filters the contents of the email notification sent when the network admin email address is changed.
	 *
	 * @since 4.9.0
	 *
	 * @param array $email_change_email {
	 *     Used to build wp_mail().
	 *
	 *     @type string $to      The intended recipient.
	 *     @type string $subject The subject of the email.
	 *     @type string $message The content of the email.
	 *         The following strings have a special meaning and will get replaced dynamically:
	 *         - ###OLD_EMAIL### The old network admin email address.
	 *         - ###NEW_EMAIL### The new network admin email address.
	 *         - ###SITENAME###  The name of the network.
	 *         - ###SITEURL###   The URL to the site.
	 *     @type string $headers Headers.
	 * }
	 * @param string $old_email  The old network admin email address.
	 * @param string $new_email  The new network admin email address.
	 * @param int    $network_id ID of the network.
	 */
	$email_change_email = apply_filters( 'network_admin_email_change_email', $email_change_email, $old_email, $new_email, $network_id );

	$email_change_email['message'] = str_replace( '###OLD_EMAIL###', $old_email, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###NEW_EMAIL###', $new_email, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###SITENAME###', $network_name, $email_change_email['message'] );
	$email_change_email['message'] = str_replace( '###SITEURL###', home_url(), $email_change_email['message'] );

	wp_mail(
		$email_change_email['to'],
		sprintf(
			$email_change_email['subject'],
			$network_name
		),
		$email_change_email['message'],
		$email_change_email['headers']
	);
}