feat: initial version

Signed-off-by: Sebastian Krupinski <root@LAPTOP-7DVOR6NC>

lib/Client/Protocol/Command/Authenticate/SASLMechanism.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Gricob\IMAP\Protocol\Command\Authenticate;
+
+use Gricob\IMAP\Protocol\Command\Argument\Argument;
+use Gricob\IMAP\Protocol\Command\Continuable;
+
+interface SASLMechanism extends Argument, Continuable
+{
+}

lib/Client/Protocol/Command/Authenticate/XOAuth2.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Gricob\IMAP\Protocol\Command\Authenticate;
+
+final readonly class XOAuth2 implements SASLMechanism
+{
+    public function __construct(
+        private string $user,
+        private string $accessToken
+    ) {
+    }
+
+    public function __toString(): string
+    {
+        return 'XOAUTH2';
+    }
+
+    public function continue(): string
+    {
+        return base64_encode(
+            sprintf("user=%s\1auth=Bearer %s\1\1", $this->user, $this->accessToken)
+        );
+    }
+}