<?php declare(strict_types=1);

namespace MailPoet\Subscribers;

if (!defined('ABSPATH')) exit;


use MailPoet\Entities\SubscriberEntity;

class LinkTokens {
  private const OBSOLETE_LINK_TOKEN_LENGTH = 6;

  /** @var SubscribersRepository */
  private $subscribersRepository;

  public function __construct(
    SubscribersRepository $subscribersRepository
  ) {
    $this->subscribersRepository = $subscribersRepository;
  }

  public function getToken(SubscriberEntity $subscriber): string {
    if ($subscriber->getLinkToken() === null) {
      $subscriber->setLinkToken($this->generateToken($subscriber->getEmail()));
      $this->subscribersRepository->flush();
    }
    return (string)$subscriber->getLinkToken();
  }

  public function verifyToken(SubscriberEntity $subscriber, string $token) {
    $databaseToken = $this->getToken($subscriber);
    $requestToken = substr($token, 0, strlen($databaseToken));
    return hash_equals($databaseToken, $requestToken);
  }

  /**
   * Only for backward compatibility for old tokens
   */
  private function generateToken(?string $email, int $length = self::OBSOLETE_LINK_TOKEN_LENGTH): ?string {
    if ($email !== null) {
      $authKey = '';
      if (defined('AUTH_KEY')) {
        $authKey = AUTH_KEY;
      }
      return substr(md5($authKey . $email), 0, $length);
    }
    return null;
  }
}
