add set elements

backend/app/Element/EloquentElementRepository.php

@@ -0,0 +1,75 @@
+<?php
+
+namespace App\Element;
+
+use App\Set\SetRepository;
+use DomainException;
+
+class EloquentElementRepository implements ElementRepository
+{
+    public function __construct(private SetRepository $setRepo) {}
+
+    public function create(CreateElementDto $dto): Element
+    {
+        $model = ElementModel::create([
+            'set_id' => $dto->set->getId(),
+            'title' => $dto->title,
+            'parent_element_id' => $dto->parentElement?->getId(),
+        ]);
+
+        return new Element(
+            id: $model->id,
+            title: $dto->title,
+            set: $dto->set,
+            parentElement: $dto->parentElement,
+        );
+    }
+
+    public function find(int $id): ?Element
+    {
+        $model = ElementModel::find($id);
+
+        return $model === null ? null : $this->toDomain($model);
+    }
+
+    /**
+     * @return Element[]
+     */
+    public function findBySetId(int $id): array
+    {
+        $models = ElementModel::where('set_id', $id)->orderBy('id')->get();
+        $elements = [];
+        foreach ($models as $model) {
+            $elements[] = $this->toDomain($model);
+        }
+
+        return $elements;
+    }
+
+    private function toDomain(ElementModel $model): Element
+    {
+        $set = $this->setRepo->find($model->set_id);
+        if ($set === null) {
+            throw new DomainException(
+                "Set with id: {$model->set_id} doesnt exist"
+            );
+        }
+
+        $parentElement = null;
+        if ($model->parent_element_id !== null) {
+            $parentElement = $this->find($model->parent_element_id);
+            if ($parentElement === null) {
+                throw new DomainException(
+                    "Element with id: {$model->parent_element_id} doesnt exist"
+                );
+            }
+        }
+
+        return new Element(
+            id: $model->id,
+            title: $model->title,
+            set: $set,
+            parentElement: $parentElement,
+        );
+    }
+}