add set elements

backend/app/Element/UseCases/CreateElement/CreateElement.php

@@ -0,0 +1,84 @@
+<?php
+
+namespace App\Element\UseCases\CreateElement;
+
+use App\Element\CreateElementDto;
+use App\Element\Element;
+use App\Element\ElementRepository;
+use App\Exceptions\BadRequestException;
+use App\Set\SetRepository;
+use DomainException;
+
+class CreateElement
+{
+    public function __construct(
+        private ElementRepository $elementRepo,
+        private SetRepository $setRepo,
+    ) {}
+
+    /**
+     * @throws BadRequestException
+     * @throws DomainException
+     */
+    public function execute(CreateElementRequest $request): Element
+    {
+        if ($request->setId === null) {
+            throw new BadRequestException('setId is required');
+        }
+        if ($request->title === null || $request->title === '') {
+            throw new BadRequestException('title is required');
+        }
+
+        $set = $this->setRepo->find($request->setId);
+        if ($set === null) {
+            throw new DomainException(
+                "Set with id: {$request->setId} doesnt exist"
+            );
+        }
+
+        if ($request->parentElementId === null) {
+            $this->validateNoRootElementExists($request->setId);
+
+            return $this->elementRepo->create(new CreateElementDto(
+                set: $set,
+                title: $request->title,
+                parentElement: null,
+            ));
+        }
+
+        $parentElement = $this->elementRepo->find(
+            $request->parentElementId
+        );
+        if ($parentElement === null) {
+            throw new DomainException(
+                "Element with id: {$request->parentElementId} doesnt exist"
+            );
+        }
+        if ($parentElement->getSet()->getId() !== $set->getId()) {
+            throw new DomainException(
+                'Parent element must belong to the same set'
+            );
+        }
+
+        return $this->elementRepo->create(new CreateElementDto(
+            set: $set,
+            title: $request->title,
+            parentElement: $parentElement,
+        ));
+    }
+
+    /**
+     * @throws DomainException
+     */
+    private function validateNoRootElementExists(int $setId): void
+    {
+        $elements = $this->elementRepo->findBySetId($setId);
+        foreach ($elements as $element) {
+            if ($element->getParentElement() === null) {
+                throw new DomainException(
+                    'A root element already exists for this set'
+                );
+            }
+        }
+    }
+}

backend/app/Element/UseCases/CreateElement/CreateElementRequest.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace App\Element\UseCases\CreateElement;
+
+class CreateElementRequest
+{
+    public function __construct(
+        public ?int $setId,
+        public ?string $title,
+        public ?int $parentElementId,
+    ) {}
+}