<?php

namespace App\Services\Email;

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception as PHPMailerException;

/**
 * Email Security Manager
 *
 * Handles security aspects of email sending like headers and authentication.
 *
 * @package App\Services\Email
 */
class EmailSecurityManager
{
    /**
     * Add security headers to email to prevent spoofing
     *
     * @param PHPMailer $mailer PHPMailer instance
     * @return void
     * @throws PHPMailerException
     */
    public function addSecurityHeaders(PHPMailer $mailer): void
    {
        $mailer->SMTPSecure = PHPMailer::ENCRYPTION_STARTTLS;
        $mailer->SMTPOptions = [
            'ssl' => [
                'crypto_method' => STREAM_CRYPTO_METHOD_TLSv1_3_CLIENT,
                'verify_peer' => true,
                'verify_peer_name' => true,
                'allow_self_signed' => false,
            ],
        ];

        // Add DKIM signature if keys are available
        if (defined('MAIL_DKIM_DOMAIN') && defined('MAIL_DKIM_PRIVATE') && defined('MAIL_DKIM_SELECTOR')) {
            $mailer->DKIM_domain = MAIL_DKIM_DOMAIN;
            $mailer->DKIM_private = MAIL_DKIM_PRIVATE;
            $mailer->DKIM_selector = MAIL_DKIM_SELECTOR;
            $mailer->DKIM_identity = $mailer->From;
        }

        // Add Message-ID header for traceability
        $mailer->MessageID = $this->generateMessageId();

        // Add X-Mailer header to identify the sending system
        $mailer->XMailer = APP_NAME . ' Mailer';

        // Add List-Unsubscribe header
        $unsubscribeEmail = 'unsubscribe@' . parse_url(APP_URL, PHP_URL_HOST);
        $unsubscribeUrl = APP_URL . '/unsubscribe?email=' . urlencode($mailer->getToAddresses()[0][0] ?? '');
        $mailer->addCustomHeader('List-Unsubscribe', "<mailto:$unsubscribeEmail>, <$unsubscribeUrl>");
        $mailer->addCustomHeader('List-Unsubscribe-Post', 'List-Unsubscribe=One-Click');
        $mailer->addCustomHeader('Precedence', 'bulk');
        $mailer->addCustomHeader('X-Auto-Response-Suppress', 'OOF, AutoReply');
    }

    /**
     * Generate a unique Message-ID for email tracking
     *
     * @return string Message ID
     */
    private function generateMessageId(): string
    {
        $domain = parse_url(APP_URL, PHP_URL_HOST) ?: 'uknp.dock';
        return '<' . uniqid(mt_rand(), true) . '@' . $domain . '>';
    }
}