Fix parsing of attachment's filename in MailgunMailer

Filename is parsed from header `Content-Disposition`. It is put there by
Nette Mailer. Previous implementation incorrectly parsed filenames with
dash. Filename of attached file "invoice-2024-09-24.pdf" would be only
last part "24.pdf".

Regex responsible for parsing header was moved into trait MailHeaderTrait
so it can be tested.

remp/remp#1386

Co-authored-by: Peter Dulacka <dulacka@gmail.com>

CHANGELOG.md

@@ -21,6 +21,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 ### [Mailer]
 
 - Added ability to set custom health check TTL for `ProcessJobCommand`. remp/remp#1376
+- Fixed parsing of attachment's filename from header within `MailgunMailer`. remp/remp#1386
+  - Previous implementation incorrectly parsed filenames with dash. Filename of attached file "invoice-2024-09-24.pdf" would be only last part "24.pdf".
+  - Added `MailHeaderTrait` with method `getHeaderParameter()` and tests to validate it.
 
 ## Archive
 

Mailer/extensions/mailer-module/src/Models/Mailer/MailHeaderTrait.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Remp\MailerModule\Models\Mailer;
+
+trait MailHeaderTrait
+{
+    /**
+     * Get parameter from header string
+     *
+     * <code>
+     * $headerValue = 'Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"';
+
+     * // $filename will contain string "invoice-2024-09-24.pdf"
+     * $filename = $this->getHeaderParameter($headerValue, 'filename');
+     * </code>
+     */
+    public function getHeaderParameter(string $headerValue, string $parameter): ?string
+    {
+        preg_match('/.*' . $parameter . '="(?<value>([^"]*))"/', $headerValue, $result);
+        return $result['value'] ?? null;
+    }
+}

Mailer/extensions/mailer-module/src/Models/Mailer/MailgunMailer.php

@@ -16,6 +16,8 @@
 
 class MailgunMailer extends Mailer
 {
+    use MailHeaderTrait;
+
     public const ALIAS = 'remp_mailgun';
 
     private ?LoggerInterface $logger = null;
@@ -117,10 +119,11 @@ public function send(Message $mail): void
 
         $attachments = [];
         foreach ($mail->getAttachments() as $attachment) {
-            preg_match('/(?<filename>\w+\.\w+)/', $attachment->getHeader('Content-Disposition'), $attachmentName);
+            // example header with attachment: `Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"`
+            $filename = $this->getHeaderParameter($attachment->getHeader('Content-Disposition'), 'filename');
             $attachments[] = [
                 'fileContent' => $attachment->getBody(),
-                'filename' => $attachmentName['filename'],
+                'filename' => $filename,
             ];
         }
 

Mailer/extensions/mailer-module/src/Tests/Feature/Mails/MailHeaderTraitTest.php

@@ -0,0 +1,73 @@
+<?php
+declare(strict_types=1);
+
+namespace Feature\Mails;
+
+use Nette\Mail\Message;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Remp\MailerModule\Models\Mailer\MailHeaderTrait;
+use Tests\Feature\BaseFeatureTestCase;
+
+class MailHeaderTraitTest extends BaseFeatureTestCase
+{
+    use MailHeaderTrait;
+
+    public static function dataProvider()
+    {
+        return [
+            'TestRegularHeader_ShouldReturnFilename' => [
+                'headerValue' => 'Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"',
+                'parameter' => 'filename',
+                'result' => 'invoice-2024-09-24.pdf',
+            ],
+            'TestRegularHeader_NotRealParameter' => [
+                'headerValue' => 'Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"',
+                'parameter' => 'dummy',
+                'result' => null,
+            ],
+            'TestRegularHeader_AdditionalParameters' => [
+                'headerValue' => 'Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"; foo="bar"',
+                'parameter' => 'filename',
+                'result' => 'invoice-2024-09-24.pdf',
+            ],
+        ];
+    }
+
+    #[DataProvider('dataProvider')]
+    public function testMailHeaderTrait(
+        string $headerValue,
+        string $parameter,
+        ?string $result,
+    ) {
+        $parameter = $this->getHeaderParameter($headerValue, $parameter);
+        $this->assertSame($result, $parameter);
+    }
+
+    /**
+     * Nette Mailer adds attachments to email as `Content-Disposition` headers with format:
+     *
+     *    Content-Disposition: attachment; filename="invoice-2024-09-24.pdf"
+     *
+     * Mailgun requires attachments as API parameters, so in MailgunMailer we need to load attachment
+     * and parse filename from header. This is handled by preg_match within `MailHeaderTrait`.
+     *
+     * This is simple unit test which checks:
+     * - If regex which loads attachment's filename from mail header is correct.
+     * - If Nette didn't change how attachments (filenames) are attached to message.
+     *   E.g. using different approach or attaching filename without quotes (allowed by specification).
+     */
+    public function testMessageMimePartHeaderForContentDisposition()
+    {
+        $filename = 'invoice-2024-09-24.pdf';
+
+        // create attachment as Nette Mailer creates it
+        $message = new Message();
+        $message->addAttachment($filename, 'dummy content', 'text/plain');
+        $attachments = $message->getAttachments();
+        $attachment = reset($attachments);
+
+        // parse header created by Nette with our Trait
+        $attachmentName = $this->getHeaderParameter($attachment->getHeader('Content-Disposition'), 'filename');
+        $this->assertEquals($filename, $attachmentName);
+    }
+}