<?php

use SilverStripe\CMS\Model\SiteTree;
use SilverStripe\Comments\Model\Comment;
use SilverStripe\ORM\ArrayList;
use SilverStripe\ORM\DataExtension;
use SilverStripe\Security\Group;

class CommentNotificationExtension extends DataExtension
{
    /**
     * @param array $existing
     * @param Comment $comment
     */
    public function updateNotificationRecipients(&$existing, $comment)
    {
        // send notification of the comment to all administrators in the CMS
        $admin = Group::get()->filter('Code', 'admin');

        foreach ($admin as $group) {
            foreach ($group->Members() as $member) {
                $existing[] = $member->Email;
            }
        }

        // or, notify the user who originally created the page
        $page = $comment->Parent();
        if ($page instanceof SiteTree) {
            /** @var ArrayList $pageVersion */
            $pageVersion = $page->allVersions('', '', 1); // get the original version
            if ($pageVersion && $pageVersion->count()) {
                $existing[] = $pageVersion->first()->Author()->Email;
            }
        }
    }
}