feat: RPC method - find user by email

lib/AdapterRpc.php

@@ -119,6 +119,41 @@ class AdapterRpc extends Adapter
         return $this->getPerunUser($idpEntityId, $uids);
     }
 
+    public function getPerunUserByEmail($emailAttrUrn, $emailValue)
+    {
+        $user = null;
+
+        $users = $this->connector->get('usersManager', 'getUsersByAttributeValue', [
+            'attributeName' => $emailAttrUrn,
+            'attributeValue' => $emailValue,
+        ]);
+
+        if (count($users) > 1) {
+            throw new Exception('Multiple users with email ' . $emailValue . ' found');
+        } elseif (count($users) === 0) {
+            throw new Exception('No users with email ' . $emailValue . ' found');
+        } else {
+            $user = $users[0];
+            $name = '';
+            if (!empty($user['titleBefore'])) {
+                $name .= $user['titleBefore'] . ' ';
+            }
+            if (!empty($user['firstName'])) {
+                $name .= $user['firstName'] . ' ';
+            }
+            if (!empty($user['middleName'])) {
+                $name .= $user['middleName'] . ' ';
+            }
+            if (!empty($user['lastName'])) {
+                $name .= $user['lastName'];
+            }
+            if (!empty($user['titleAfter'])) {
+                $name .= ' ' . $user['titleAfter'];
+            }
+            return new User($user['id'], $name);
+        }
+    }
+
     public function getMemberGroups($user, $vo)
     {
         try {