feat: blobs fetch

Signed-off-by: Sebastian Krupinski <krupinski01@gmail.com>

lib/Controllers/DefaultController.php

@@ -162,6 +162,7 @@ class DefaultController extends ControllerAbstract {
             'entity.copy' => throw new InvalidArgumentException('Operation not implemented: ' . $operation),
             'entity.submit' => $this->entitySubmit($tenantId, $userId, $data),
             'entity.download' => $this->entityDownload($tenantId, $userId, $data),
+            'entity.blobs' => $this->entityBlobs($tenantId, $userId, $data),
             
             default => throw new InvalidArgumentException(self::ERR_INVALID_OPERATION . $operation)
         };
@@ -895,5 +896,43 @@ class DefaultController extends ControllerAbstract {
             'Cache-Control'             => 'no-store',
         ]);
     }
+    
+    private function entityBlobs(string $tenantId, string $userId, array $data): mixed {
+        if (!isset($data['target'])) {
+            throw new InvalidArgumentException(self::ERR_MISSING_TARGET);
+        }
+        if (!is_string($data['target'])) {
+            throw new InvalidArgumentException(self::ERR_INVALID_IDENTIFIER);
+        }
+        if (!isset($data['parts']) || !is_array($data['parts']) || $data['parts'] === []) {
+            throw new InvalidArgumentException('At least one part selector is required');
+        }
+
+        $target = ResourceIdentifier::fromString($data['target']);
+
+        $results = [];
+        foreach ($data['parts'] as $part) {
+            if (!is_array($part)) {
+                throw new InvalidArgumentException('Invalid part selector');
+            }
+
+            $resource = $this->mailManager->entityDownload($tenantId, $userId, $target, $part);
+
+            $bytes = '';
+            foreach ($resource->stream() as $chunk) {
+                $bytes .= $chunk;
+            }
+
+            $results[] = [
+                'source'   => $data['target'],
+                'part'     => $part,
+                'mime'     => $resource->mimeType(),
+                'filename' => $resource->filename(),
+                'bytes'    => base64_encode($bytes),
+            ];
+        }
+
+        return $results;
+    }
 
 }