Notion backlinks checker

index.php

<?php

/*
 * Notion Backlinks Checker in PHP
 * PHP requirement: https://github.com/brd6/notion-sdk-php
 * Notion requirement: database table with columns: Name, OK, URL, Target, My URL, My Target, Contact, Latest Check
 * read more:
 * [CZ]: https://www.maxiorel.cz/notion-php-backlink-kontrola 
 * [EN] https://www.maxiorel.com/notion-php-backlink-checker
 * */

require "vendor/autoload.php";

use Brd6\NotionSdkPhp\Client;
use Brd6\NotionSdkPhp\ClientOptions;
use \Brd6\NotionSdkPhp\Resource\Database\DatabaseRequest;

// Slightly modified version of https://gist.github.com/nedevl/f6fb87ab53f3c765c8eb5e09b16817fe
function backlinkCheck($backlink, $url) {

  $backlinkexists = false;
  $backlinknofollow = false;
  
  $content = file_get_contents($url);

  $dom = new DomDocument();
  libxml_use_internal_errors(true);
  $dom -> loadHTML($content);
  $anchors = $dom -> getElementsByTagName('a');
  libxml_clear_errors();

  foreach ($anchors as $anchor) {
    $link = $anchor -> getAttribute("href");

    //check if the link exists among links on the $url
    if ($link == $backlink) {
      $backlinkexists = true;

      $anchorhtml = strtolower($anchor -> C14N());

      if (strpos($anchorhtml, 'nofollow') !== false) {
        $backlinknofollow = true;
      }

      break;
    }
  }

  if ($backlinkexists && !$backlinknofollow) {
    // backlink exists and it doesn't has a rel attribute with nofollow value
    return TRUE;
  } else if ($backlinkexists && $backlinknofollow) {
    // backlink exists and it does has a rel attribute with nofollow value
    return FALSE;
  } else {
    // backlink doesn't exists
    return FALSE;
  }

}

$options = (new ClientOptions())
  ->setAuth('YOUR_NOTION_INTEGRATION_TOKEN');
$notion = new Client($options);
$databaseRequest = new DatabaseRequest();
$myPage = $notion->databases()->query('YOUR_DATABASE_MACHINE_NAME', $databaseRequest);
$results = $myPage->getResults();
foreach ($results as $result){
  $page = $notion->pages()->retrieve($result->getId());
  $properties = $page->getProperties();
  $url = $properties['URL']->getUrl();
  echo 'Checking '.$url. "\n";
  $target = $properties['Target']->getUrl();
  $check = backlinkCheck( $target, $url);
  $properties['OK']->setCheckbox($check);
  $page->setProperties([
    'OK' => $properties['OK'],
    'Latest Check' => ['date' => ['start' => date('c'), 'end' => date('c')] ]
  ]);
  $pageUpdated = $notion->pages()->update($page);
}