Add method getUserBackendName() to UserGroupBackendInterface

refs #10367
refs #10373

application/views/scripts/group/show.phtml

@@ -2,7 +2,6 @@
 
 use Icinga\Data\Extensible;
 use Icinga\Data\Updatable;
-use Icinga\Data\Selectable;
 
 $extensible = $this->hasPermission('config/authentication/groups/add') && $backend instanceof Extensible;
 
@@ -85,12 +84,10 @@ foreach ($members as $member): ?>
         <td class="member-name">
         <?php if (
           $this->hasPermission('config/authentication/users/show')
-          && method_exists($backend, 'getUserBackend')
-          && ($userBackend = $backend->getUserBackend()) !== null
-          && $userBackend instanceof Selectable
+          && ($userBackend = $backend->getUserBackendName($member->user_name)) !== null
         ): ?>
           <?= $this->qlink($member->user_name, 'user/show', array(
-            'backend' => $userBackend->getName(),
+            'backend' => $userBackend,
             'user'    => $member->user_name
           ), array(
             'title'   => sprintf($this->translate('Show detailed information about %s'), $member->user_name)

library/Icinga/Authentication/UserGroup/DbUserGroupBackend.php

@@ -217,6 +217,18 @@ class DbUserGroupBackend extends DbRepository implements UserGroupBackendInterfa
         return $memberships;
     }
 
+    /**
+     * Return the name of the backend that is providing the given user
+     *
+     * @param   string  $username   Currently unused
+     *
+     * @return  null|string     The name of the backend or null in case this information is not available
+     */
+    public function getUserBackendName($username)
+    {
+        return null; // TODO(10373): Store this to the database when inserting and fetch it here
+    }
+
     /**
      * Join group into group_membership
      *

library/Icinga/Authentication/UserGroup/LdapUserGroupBackend.php

@@ -560,6 +560,21 @@ class LdapUserGroupBackend extends LdapRepository implements UserGroupBackendInt
         return $groups;
     }
 
+    /**
+     * Return the name of the backend that is providing the given user
+     *
+     * @param   string  $username   Unused
+     *
+     * @return  null|string     The name of the backend or null in case this information is not available
+     */
+    public function getUserBackendName($username)
+    {
+        $userBackend = $this->getUserBackend();
+        if ($userBackend !== null) {
+            return $userBackend->getName();
+        }
+    }
+
     /**
      * Apply the given configuration on this backend
      *

library/Icinga/Authentication/UserGroup/UserGroupBackendInterface.php

@@ -34,4 +34,13 @@ interface UserGroupBackendInterface
      * @return  array
      */
     public function getMemberships(User $user);
+
+    /**
+     * Return the name of the backend that is providing the given user
+     *
+     * @param   string  $username
+     *
+     * @return  null|string     The name of the backend or null in case this information is not available
+     */
+    public function getUserBackendName($username);
 }