IcingaNotificationForm: enforce & render apply to

fixes #11895

application/forms/IcingaNotificationForm.php

@@ -41,6 +41,24 @@ class IcingaNotificationForm extends DirectorObjectForm
             return $this;
         }
 
+        $this->addElement(
+            'select',
+            'apply_to',
+            array(
+                'label' => $this->translate('Apply to'),
+                'description' => $this->translate(
+                    'Whether this notification should affect hosts or services'
+                ),
+                'required'    => true,
+                'multiOptions' => $this->optionalEnum(
+                    array(
+                        'host'    => $this->translate('Hosts'),
+                        'service' => $this->translate('Services'),
+                    )
+                )
+            )
+        );
+
         $sub = new AssignListSubForm();
         $sub->setObject($this->getObject());
         $sub->setup();

library/Director/Objects/IcingaNotification.php

@@ -111,6 +111,43 @@ class IcingaNotification extends IcingaObject
         );
     }
 
+    /**
+     * Do not render internal property apply_to
+     *
+     * Avoid complaints for method names with underscore:
+     * @codingStandardsIgnoreStart
+     *
+     * @return string
+     */
+    public function renderApply_to()
+    {
+        // @codingStandardsIgnoreEnd
+        return '';
+    }
+
+    protected function renderObjectHeader()
+    {
+        if ($this->isApplyRule()) {
+            if (($to = $this->get('apply_to')) === null) {
+                throw new ConfigurationError(
+                    'Applied notification "%s" has no valid object type',
+                    $this->getObjectName()
+                );
+            }
+
+            return sprintf(
+                "%s %s to %s %s {\n",
+                $this->getObjectTypeName(),
+                $this->getType(),
+                ucfirst($to),
+                c::renderString($this->getObjectName())
+            );
+
+        } else {
+            return parent::renderObjectHeader();
+        }
+    }
+
     protected function setKey($key)
     {
         if (is_int($key)) {

library/Director/Web/Form/DirectorObjectForm.php

@@ -493,6 +493,7 @@ abstract class DirectorObjectForm extends QuickForm
             'groups',
             'users',
             'user_groups',
+            'apply_to',
             'command_id', // Notification
             'notification_interval',
             'period_id',