Pro Sites - Notification for pro site owners

ps-notice-by-level.php

<?php
/*
Plugin Name: Pro Sites - Notification for pro site owners
Plugin URI: https://premium.wpmudev.org/
Description: Displays different notifications for users if they are logged out, logged in but don't have a pro site, logged in and have at least one pro site.
Author: Panos Lyrakis @ WPMUDEV
Author URI: https://premium.wpmudev.org/
License: GPLv2 or later
*/
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'WPMUDEV_PS_Notice_By_Level' ) ) {

	class WPMUDEV_PS_Notice_By_Level {

		private static $_instance = null;
		
		public static function get_instance() {
			if( is_null( self::$_instance ) ){
				self::$_instance = new WPMUDEV_PS_Notice_By_Level();
			}
			return self::$_instance;
		}


		public function __construct() {

			add_shortcode( 'wpmudev_ps_notice', array( $this, 'ps_notice' ) );

		}

		public function get_logged_out_message(){

			return __( 'Message for loggedout visitors', 'psts' );

		}


		public function get_user_message_pro_level(){

			return __( 'Message for users with at least one pro site', 'psts' );

		}

		public function get_user_message_not_pro_level(){
			return __( 'Message for users with NO pro site', 'psts' );
		}


		public function ps_notice( $atts ){

			$atts = shortcode_atts(
				array(
					'user_id' => null
				), $atts, 'ps_notice' 
			);

			if( ! function_exists( 'is_pro_site' ) ){
				return;
			}

			if( ! is_user_logged_in() && $atts['user_id'] == null ){
				return $this->get_logged_out_message();
			}

			$user_id = ( is_numeric( $atts['user_id'] ) && $atts['user_id'] != null ) ? (int)$atts['user_id'] : get_current_user_id();

			$user_blogs = get_blogs_of_user( $user_id );
			$user_has_pro_site = false;

            foreach ( $user_blogs as $blog ) {

                if ( is_pro_site( $blog->userblog_id ) && ! is_pro_trial( $blog->userblog_id ) ) {
                	
	                $mail = get_blog_option( $blog->userblog_id, 'admin_email' );
					$user_from_email = get_user_by( 'email', $mail );

					if( $user_id == $user_from_email->ID ){
						return $this->get_user_message_pro_level();
					}
                }

            }

            return $this->get_user_message_not_pro_level();

		}

	}

	add_action( 'plugins_loaded', function(){
		$GLOBALS['WPMUDEV_PS_Notice_By_Level'] = WPMUDEV_PS_Notice_By_Level::get_instance();
	}, 10 );

}