Add delete button to modify view

The modify view for the process form must contain delete button. This allows the user to either
store the modifications or delete the process node.

application/forms/ProcessForm.php

@@ -10,6 +10,7 @@
 use Icinga\Web\Notification;
 use Icinga\Web\Session\SessionNamespace;
 use ipl\Sql\Connection as IcingaDbConnection;
+use ipl\Web\Url;
 
 class ProcessForm extends QuickForm
 {
@@ -109,6 +110,13 @@ public function setup()
                 $this->getElement('url')->setValue($node->getInfoUrl());
             }
         }
+
+        $label = $this->translate('Delete');
+        $el = $this->createElement('submit', $label, array(
+            'data-base-target' => '_main'
+        ))->setLabel($label)->setDecorators(array('ViewHelper'));
+        $this->deleteButtonName = $el->getName();
+        $this->addElement($el);
     }
 
     /**
@@ -152,6 +160,33 @@ public function setSession(SessionNamespace $session)
         return $this;
     }
 
+    protected function onRequest()
+    {
+        $params = Url::fromRequest()->getParams();
+        if ($this->shouldBeDeleted()) {
+            $url = Url::fromRequest()->without(array_keys($params->toArray()));
+
+            $url->setParams([
+                'config' => $params->get('config'),
+                'node' => $params->get('path'),
+                'unlocked' => 1,
+                'action' => 'delete',
+                'deletenode' => $params->get('editnode')
+            ]);
+
+            $this->redirectAndExit($url);
+        }
+    }
+
+    protected function getNode(BpConfig $bp, $nodeName)
+    {
+        if ($nodeName) {
+            return $bp->getNode($nodeName);
+        } else {
+            return null;
+        }
+    }
+
     public function onSuccess()
     {
         $changes = ProcessChanges::construct($this->bp, $this->session);
@@ -212,4 +247,19 @@ public function onSuccess()
 
         parent::onSuccess();
     }
+
+    public function hasDeleteButton()
+    {
+        return $this->deleteButtonName !== null;
+    }
+
+    public function shouldBeDeleted()
+    {
+        if (! $this->hasDeleteButton()) {
+            return false;
+        }
+
+        $name = $this->deleteButtonName;
+        return $this->getSentValue($name) === $this->getElement($name)->getLabel();
+    }
 }