add persisted set ordering

backend/app/Set/UseCases/ReorderSets/ReorderSets.php

@@ -0,0 +1,128 @@
+<?php
+
+namespace App\Set\UseCases\ReorderSets;
+
+use App\Exceptions\BadRequestException;
+use App\Set\Set;
+use App\Set\SetRepository;
+
+class ReorderSets
+{
+    public function __construct(private SetRepository $setRepository)
+    {
+    }
+
+    /**
+     * @return Set[]
+     * @throws BadRequestException
+     */
+    public function execute(ReorderSetsRequest $request): array
+    {
+        if ($request->setIds === null) {
+            throw new BadRequestException('setIds is required');
+        }
+
+        $setIds = $this->validatedSetIds($request->setIds);
+        $existingSetIds = $this->setIds($this->setRepository->getAll());
+
+        $this->validateNoDuplicateIds($setIds);
+        $this->validateAllIdsAreSets($setIds, $existingSetIds);
+        $this->validateEverySetWasSubmitted($setIds, $existingSetIds);
+
+        return $this->setRepository->reorder($setIds);
+    }
+
+    /**
+     * @param mixed[] $setIds
+     * @return int[]
+     * @throws BadRequestException
+     */
+    private function validatedSetIds(array $setIds): array
+    {
+        $validatedSetIds = [];
+        foreach ($setIds as $setId) {
+            if (! is_int($setId)) {
+                throw new BadRequestException(
+                    'setIds must contain integers',
+                );
+            }
+
+            $validatedSetIds[] = $setId;
+        }
+
+        return $validatedSetIds;
+    }
+
+    /**
+     * @param int[] $setIds
+     * @throws BadRequestException
+     */
+    private function validateNoDuplicateIds(array $setIds): void
+    {
+        $seenSetIds = [];
+        foreach ($setIds as $setId) {
+            if (isset($seenSetIds[$setId])) {
+                throw new BadRequestException(
+                    'Set order contains duplicate ids',
+                );
+            }
+
+            $seenSetIds[$setId] = true;
+        }
+    }
+
+    /**
+     * @param int[] $setIds
+     * @param int[] $existingSetIds
+     * @throws BadRequestException
+     */
+    private function validateAllIdsAreSets(
+        array $setIds,
+        array $existingSetIds,
+    ): void {
+        $existingSetIdsById = [];
+        foreach ($existingSetIds as $existingSetId) {
+            $existingSetIdsById[$existingSetId] = true;
+        }
+
+        foreach ($setIds as $setId) {
+            if (! isset($existingSetIdsById[$setId])) {
+                throw new BadRequestException(
+                    'Set order contains invalid set',
+                );
+            }
+        }
+    }
+
+    /**
+     * @param int[] $setIds
+     * @param int[] $existingSetIds
+     * @throws BadRequestException
+     */
+    private function validateEverySetWasSubmitted(
+        array $setIds,
+        array $existingSetIds,
+    ): void {
+        if (count($setIds) === count($existingSetIds)) {
+            return;
+        }
+
+        throw new BadRequestException(
+            'Set order must include every set',
+        );
+    }
+
+    /**
+     * @param Set[] $sets
+     * @return int[]
+     */
+    private function setIds(array $sets): array
+    {
+        $setIds = [];
+        foreach ($sets as $set) {
+            $setIds[] = $set->getId();
+        }
+
+        return $setIds;
+    }
+}