Close #15 added two factor authentication

src/User/Service/TwoFactorQrCodeUriGeneratorService.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Da\User\Service;
+
+use Da\TwoFA\Manager;
+use Da\TwoFA\Service\QrCodeDataUriGeneratorService;
+use Da\TwoFA\Service\TOTPSecretKeyUriGeneratorService;
+use Da\User\Contracts\ServiceInterface;
+use Da\User\Model\User;
+use Yii;
+
+class TwoFactorQrCodeUriGeneratorService implements ServiceInterface
+{
+    /**
+     * @var User
+     */
+    protected $user;
+
+    /**
+     * TwoFactorQrCodeUriGeneratorService constructor.
+     *
+     * @param User $user
+     */
+    public function __construct(User $user)
+    {
+        $this->user = $user;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function run()
+    {
+        $user = $this->user;
+        if (!$user->auth_tf_key) {
+            $user->auth_tf_key = (new Manager())->generateSecretKey();
+            $user->updateAttributes(['auth_tf_key']);
+        }
+
+        $totpUri = (new TOTPSecretKeyUriGeneratorService(Yii::$app->name, $user->email, $user->auth_tf_key))->run();
+        $dataUri = (new QrCodeDataUriGeneratorService($totpUri))->run();
+
+        return $dataUri;
+    }
+
+}