Implement IMAP email-to-ticket gateway

TemplateInstaller.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Box\Mod\Mailgateway;
+
+use Pimple\Container;
+
+class TemplateInstaller
+{
+    public function __construct(private Container $di) {}
+
+    public function install(): void
+    {
+        $code = 'mailgateway_sender_mismatch';
+        $email = $this->di['mod_service']('email');
+        // Preserve existing custom content and enabled/disabled preference.
+        if ($email->getTemplateRepository()->findOneByActionCode($code) !== null) {
+            return;
+        }
+        $source = file_get_contents(__DIR__ . '/templates/email/' . $code . '.html.twig');
+        if (!is_string($source)
+            || !preg_match('/{%\s*block subject\s*%}(.*?){%\s*endblock\s*%}/s', $source, $subject)
+            || !preg_match('/{%\s*block content\s*%}(.*?){%\s*endblock\s*%}/s', $source, $content)) {
+            throw new \RuntimeException('Mail Gateway sender-mismatch template is missing or invalid');
+        }
+        // This existing custom action code does not use the mod_* discovery convention.
+        $email->templateCreate($code, trim($subject[1]), trim($content[1]), 1, 'mailgateway');
+    }
+}