[MIG] attachment_s3: Migration to 18.0

attachment_s3/s3uri.py

@@ -2,19 +2,23 @@
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html)
 
 import re
-
+from typing import Optional
 
 class S3Uri:
-    _url_re = re.compile("^s3:///*([^/]*)/?(.*)", re.IGNORECASE | re.UNICODE)
+    _url_re = re.compile(r"^s3://+([^/]+)/?(.*)", re.IGNORECASE | re.UNICODE)
 
-    def __init__(self, uri):
+    def __init__(self, uri: str) -> None:
         match = self._url_re.match(uri)
         if not match:
-            raise ValueError("%s: is not a valid S3 URI" % (uri,))
-        self._bucket, self._item = match.groups()
+            raise ValueError(f"{uri}: is not a valid S3 URI")
+        
+        self._bucket: str = match.group(1)
+        self._item: Optional[str] = match.group(2) if match.group(2) else None
 
-    def bucket(self):
+    @property
+    def bucket(self) -> str:
         return self._bucket
 
-    def item(self):
+    @property
+    def item(self) -> Optional[str]:
         return self._item