FileTransport to store sent emails on disk

EmailFileHelper.php

<?php

namespace App\Email;

use Symfony\Bridge\Twig\Mime\TemplatedEmail;
use Symfony\Component\Finder\Finder;
use Symfony\Component\Mime\Email;

/**
 * Helper to deal with messages as dumped by FileTransport.
 * Everything is public and static, as it will be used in unit/functional tests.
 */
class EmailFileHelper
{
    public static $path = __DIR__.'/../../../'.FileTransport::FOLDER;
    private static $finder; // Singleton to save a little bit of memory

    public static function countMessages()
    {
        return self::getFinder()->count();
    }

    public static function has(int $emailIndex): bool
    {
        $files = iterator_to_array(self::getFinder()->getIterator(), false);

        return isset($files[$emailIndex]);
    }

    public static function read(int $emailIndex): Email
    {
        $files = iterator_to_array(self::getFinder()->getIterator(), false);

        if (!isset($files[$emailIndex])) {
            throw new \Exception('No emails available for index '.$emailIndex);
        }

        $file = $files[$emailIndex];

        $data = $file->getContents();

        $unserialized = unserialize($data);

        if (TemplatedEmail::class === $unserialized['class']) {
            // TemplatedEmail serialization format is incompatible
            $email = new TemplatedEmail();
            $email->unserialize($unserialized['data']);
        } else {
            // We consider it is a normal Email
            $email = new Email();
            $email->unserialize($unserialized['data']);
        }

        return $email;
    }

    public function getFilename(int $emailIndex): string
    {
        $files = iterator_to_array(self::getFinder()->getIterator(), false);

        if (!isset($files[$emailIndex])) {
            throw new \Exception('No emails available for index '.$emailIndex);
        }

        return $files[$emailIndex]->getPathname();
    }

    private static function getFinder(): Finder
    {
        if (!self::$finder) {
            self::$finder = (new Finder())
                ->in(self::$path)
                ->name('*.ser')
                ->files()
            ;
        }

        return self::$finder;
    }
}

FileTransport.php

<?php

namespace App\Email;

use Symfony\Component\Filesystem\Filesystem;
use Symfony\Component\Mailer\SentMessage;
use Symfony\Component\Mailer\Transport\AbstractTransport;
use Symfony\Component\Mime\Email;

/**
 * File transport used in tests, we store messages on disk.
 */
class FileTransport extends AbstractTransport
{
    const FOLDER = 'var/emails';
    const FILE_EXTENSION = 'ser';

    private $path;

    public function setProjectDir(string $path): void
    {
        $this->path = sprintf('%s/%s', $path, self::FOLDER);
    }

    protected function doSend(SentMessage $message): void
    {
        $filesystem = new Filesystem();

        if (!$filesystem->exists($this->path)) {
            $filesystem->mkdir($this->path);
        }

        $filename = uniqid('message_');

        // We should get rendered Message - called "original", the other "RawMessage" is a Generator to generate body chunk-by-chunk.
        $email = $message->getOriginalMessage();

        // We can serialize only Emails
        if (!$email instanceof Email) {
            return;
        }

        // We keep classname around, as TemplatedEmail and Email serialization are incompatible
        $serialized = [
            'class' => get_class($email),
            'data' => $email->serialize(),
        ];

        $filesystem->dumpFile(
            sprintf('%s/%s.%s', $this->path, $filename, self::FILE_EXTENSION),
            serialize($serialized)
        );
    }
}