extract pdf use case

backend/app/Element/UseCases/GetElementPdf/GetElementPdf.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace App\Element\UseCases\GetElementPdf;
+
+use App\Exceptions\NotFoundException;
+use App\Shared\Files\StoredFileReader;
+
+class GetElementPdf
+{
+    private const PDF_FOLDERS = ['short', 'long'];
+
+    private const PDF_MIME_TYPE = 'application/pdf';
+
+    public function __construct(private StoredFileReader $storedFileReader)
+    {
+    }
+
+    /**
+     * @throws NotFoundException
+     */
+    public function execute(GetElementPdfRequest $request): GetElementPdfResult
+    {
+        if (!$this->isAllowedPdfFolder($request->folder)) {
+            throw new NotFoundException('PDF not found');
+        }
+
+        if (!$this->isValidPdfFileName($request->fileName)) {
+            throw new NotFoundException('PDF not found');
+        }
+
+        $path = "element-pdfs/$request->folder/$request->fileName";
+        $contents = $this->storedFileReader->read($path);
+        if ($contents === null) {
+            throw new NotFoundException('PDF not found');
+        }
+
+        return new GetElementPdfResult(
+            contents: $contents,
+            fileName: $request->fileName,
+            mimeType: self::PDF_MIME_TYPE,
+        );
+    }
+
+    private function isAllowedPdfFolder(string $folder): bool
+    {
+        return in_array($folder, self::PDF_FOLDERS, true);
+    }
+
+    private function isValidPdfFileName(string $fileName): bool
+    {
+        return preg_match('/^[A-Za-z0-9._-]+\.pdf$/', $fileName) === 1;
+    }
+}