re #22 added impersonation

src/User/Service/SwitchIdentityService.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the 2amigos/yii2-usuario project.
+ *
+ * (c) 2amigOS! <http://2amigos.us/>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace Da\User\Service;
+
+use Da\User\Contracts\ServiceInterface;
+use Da\User\Controller\AdminController;
+use Da\User\Event\UserEvent;
+use Da\User\Model\User;
+use Da\User\Module;
+use Da\User\Query\UserQuery;
+use Da\User\Traits\ContainerAwareTrait;
+use Yii;
+use yii\web\ForbiddenHttpException;
+use yii\web\IdentityInterface;
+
+class SwitchIdentityService implements ServiceInterface
+{
+    use ContainerAwareTrait;
+
+    protected $controller;
+    protected $switchIdentitySessionKey;
+    protected $userId;
+    protected $userQuery;
+
+    public function __construct(AdminController $controller, $userId, UserQuery $userQuery)
+    {
+        /** @var Module $module */
+        $module = $controller->module;
+        $this->controller = $controller;
+        $this->switchIdentitySessionKey = $module->switchIdentitySessionKey;
+        $this->userId = $userId;
+        $this->userQuery = $userQuery;
+    }
+
+    public function run()
+    {
+        $session = Yii::$app->session;
+        if (null === $this->userId) { // switch back identities
+            $user = $this->userQuery->whereId($session->get($this->switchIdentitySessionKey))->one();
+            $session->remove($this->switchIdentitySessionKey);
+        } else {
+            /** @var User $identity */
+            $identity = Yii::$app->user->identity;
+            if (!$identity->getIsAdmin()) {
+                // Only admins allowed on module. Developers can override the service and implement different
+                // approach. For example, by roles other than, and including, admin.
+                throw new ForbiddenHttpException();
+            }
+            $user = $this->userQuery->whereId($this->userId)->one();
+            $session->set($this->switchIdentitySessionKey, $this->userId);
+        }
+
+        $event = $this->make(UserEvent::class, [$user]);
+
+        $this->controller->trigger(UserEvent::EVENT_BEFORE_SWITCH_IDENTITY, $event);
+        /** @var IdentityInterface $user */
+        Yii::$app->user->switchIdentity($user, $session->timeout);
+        $this->controller->trigger(UserEvent::EVENT_AFTER_SWITCH_IDENTITY, $event);
+    }
+}