Add EventPage model with sortedDates method

site/models/event.php

@@ -0,0 +1,26 @@
+<?php
+
+class EventPage extends Page
+{
+    public function sortedDates(): array
+    {
+        $groups = array_values($this->dates()->toStructure()->data());
+
+        usort($groups, fn($a, $b) => strcmp(
+            $this->firstDateOf($a),
+            $this->firstDateOf($b)
+        ));
+
+        return $groups;
+    }
+
+    private function firstDateOf($group): string
+    {
+        $dates = array_filter(array_map(
+            fn($item) => $item->date()->value(),
+            array_values($group->dates()->toStructure()->data())
+        ));
+
+        return !empty($dates) ? min($dates) : '';
+    }
+}