unpublish page, create delete holder to remove algolia object

.gitignore

@@ -0,0 +1 @@
+/.idea/

src/PageAlgoliaExtension.php

@@ -18,5 +18,23 @@ public function onBeforeDelete()
             $holder->write();
         }
     }
-
+    /**
+     * To keep track of the state of our SiteTree, we need to track the unpublished pages so we can remove those from Algolia.
+     * Before a page gets deleted, create an object holding the ID.
+     */
+    public function onBeforeWrite()
+    {
+        if ($this->isInDb()) {
+            if(!$this->isPublished()) {
+                if (DeletedPageAlgoliaObjectIDHolder::get()->filter('AlgoliaObjectID', $this->owner->ID)->count() == 0) {
+                    $holder = DeletedPageAlgoliaObjectIDHolder::create();
+                    $holder->AlgoliaObjectID = $this->owner->ID;
+                    $holder->write();
+                }
+            }
+        }
+        parent::onBeforeWrite();
+
+
+    }
 }