feat: add handling for virtualized ElementController (#39)

_config/extensions.yml

@@ -1,10 +1,15 @@
 ---
 Name: elementalvirtual
-After: 'elemental'
+After: "elemental"
 ---
 DNADesign\Elemental\Models\BaseElement:
   extensions:
     - DNADesign\ElementalVirtual\Extensions\BaseElementExtension
 SilverStripe\Admin\LeftAndMain:
   extra_requirements_css:
-    - 'dnadesign/silverstripe-elemental-virtual:css/elemental-admin.css'
+    - "dnadesign/silverstripe-elemental-virtual:css/elemental-admin.css"
+SilverStripe\CMS\Controllers\ContentController:
+  extensions:
+    - DNADesign\ElementalVirtual\Extensions\VirtualElementalContentControllerExtension
+  url_handlers:
+    "element/$ID!": "handleElement"

src/Extension/VirtualElementContentControllerExtension.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace DNADesign\ElementalVirtual\Extensions;
+
+use DNADesign\Elemental\Models\BaseElement;
+use SilverStripe\Core\Extension;
+
+class VirtualElementalContentControllerExtension extends Extension
+{
+    /**
+     * @var array
+     */
+    private static $allowed_actions = [
+        'handleElement'
+    ];
+
+    public function handleElement()
+    {
+        $id = $this->owner->getRequest()->param('ID');
+
+        if (!$id) {
+            return $this->owner->httpError(400, 'no element ID provided');
+        }
+
+        $element = BaseElement::get()->filter('ID', $id)->First();
+        $page = $this->owner->data();
+
+        if ($element && $element->canView()) {
+            $useElement = clone $element;
+
+            // modify the element to appear on the correct 'Page' so that
+            // any breadcrumbs and titles are correct.
+            $elementalAreaRelations = $this->owner->getElementalRelations();
+            $id = null;
+
+            foreach ($elementalAreaRelations as $elementalAreaRelation) {
+                $id = $page->$elementalAreaRelation()->ID;
+
+                if ($id) {
+                    break;
+                }
+            }
+
+            $useElement->ParentID = $id;
+            $useElement->setAreaRelationNameCache($elementalAreaRelation);
+            $controller = $useElement->getController();
+
+            return $controller;
+        }
+
+        return $this->owner->httpError(404);
+    }
+}