PageManager.php

<?php
namespace TestPlugin {
    use TestPlugin\PageInfo;

    /**
     *  A class used to managed pages created by this plugin
     * @package TestPlugin
     */
    class PageManager {
        private $pluginName = "";

        /**
         * The generic placeholder text to be saved as the plugin page's post content. This uses the special placeholder "{pluginName}" to "inject" the plugin name dynamically.
         */
        private static $genericPageContent = "<h1>Plugin Generated Page<h1> <div>Page content generated by the plugin \"{pluginName}\". If you're seeing this, the plugin isn't activated/installed or the plugin's template file wasn't loaded.</div>";

        private $pageFolder = "";
        public function __construct($folder = "", $pluginName = "") {
            $this->pageFolder = $folder;
            $this->pluginName = $pluginName;
        }

        /**
         * Given PageInfo, this verifies a plugin page exists. If this page doesn't exist, it'll be created.
         * <b> This method CANNOT be used before the "init" WordPress Hook </b>
         *
         * @param PageInfo $pageToCheck The page to verify exists (and creates it if it doesn't)
         */
        public function ensureBasicPluginPageExists(PageInfo $pageToCheck) {
            $pagePost = get_page_by_title($pageToCheck->pageTitle);

            if (($pagePost === NULL) || ($pagePost === FALSE)) {//doesn't exist, so create it
                PageManager::createPluginPage($pageToCheck);
            } else {//already exists
                // the plugin may have been previously active and the page may just be trashed
                if($pagePost->post_status != 'publish') {
                    $pagePost->post_status = 'publish';
                    wp_update_post($pagePost);
                }
            }
        }

        /**
         * Given PageInfo, this creates a plugin page.
         * <b> This method CANNOT be used before the "init" WordPress Hook </b>
         *
         * @param PageInfo $pageToCreate The page to create
         * @return int The id of the plugin page's post ID
         */
        public function createPluginPage(PageInfo $pageToCreate):int {
            global $wp_rewrite;

            // Create post object
            $p = array();
            $newPageGuid = implode("/",[site_url(),$pageToCreate->getPostName(),""]);

            $p['post_title'] = $pageToCreate->pageTitle;
            $p['post_name'] = $pageToCreate->getPostName();
            $p['post_content'] = str_replace('{pluginName}',$this->pluginName,PageManager::$genericPageContent);
            $p['post_status'] = 'publish';
            $p['post_type'] = 'page';
            $p['comment_status'] = 'closed';
            $p['ping_status'] = 'closed';
            $p['post_category'] = array(1); // the default :'Uncategorised'

            // Insert the post
            $the_page_id = wp_insert_post($p);

            return $the_page_id;
        }

        /**
         * Given PageInfo, this <b>deletes</b> a plugin page.
         *
         * @param PageInfo $page The page to delete
         */
        public function deletePluginPage(PageInfo $page) {
            $pagePost = get_page_by_title($page->pageTitle);

            if (($pagePost !== NULL) && ($pagePost !== FALSE)) {
                wp_delete_post($pagePost->ID, true);
            }
        }
    }
}