pressbooks-aldine/app/activation.php

<?php

namespace Aldine;

add_action('admin_init', function () {
    $extra = new \ParsedownExtra();
    $about = $extra->text(file_get_contents(get_stylesheet_directory() . '/docs/about.md'));
    $help = $extra->text(file_get_contents(get_stylesheet_directory() . '/docs/help.md'));

    $default_pages = [
        'about' => [
            'post_title' => __('About', 'aldine'),
            'post_content' => apply_filters('pb_root_about_page_content', $about)
        ],
        'help' => [
            'post_title' => __('Help', 'aldine'),
            'post_content' => apply_filters('pb_root_help_page_content', $help)
        ],
        'catalog' => [
            'post_title' => __('Catalog', 'aldine'),
            'post_content' => ''
        ],
        'home' => [
            'post_title' => __('Home', 'aldine'),
            'post_content' => ''
        ],
    ];

    if (! get_option('pb_aldine_activated')) {
        // Add our pages
        $pages = [];

        foreach ($default_pages as $slug => $page) {
            $check = get_page_by_path($slug);
            if (empty($check)) {
                $pages[$slug] = wp_insert_post(array_merge($page, ['post_type' => 'page', 'post_status' => 'publish']));
            } else {
                $pages[$slug] = $check->ID;
            }
        }

        // Set front page to Home
        update_option('show_on_front', 'page');
        update_option('page_on_front', $pages['home']);

        // Remove content generated by wp_install_defaults
        if (! wp_delete_post(1, true)) {
            return;
        }
        if (! wp_delete_post(2, true)) {
            return;
        }
        if (! wp_delete_comment(1, true)) {
            return;
        }

        // Add "pb_aldine_activated" option to enable check above
        add_option('pb_aldine_activated', 1);
    }
});