Add typing in sseconfig.py (#1351)

Signed-off-by: Bala.FA <[email protected]>

minio/sseconfig.py

@@ -16,54 +16,71 @@
 
 """Request/response of PutBucketEncryption and GetBucketEncryption APIs."""
 
-from __future__ import absolute_import
+from __future__ import absolute_import, annotations
 
 from abc import ABCMeta
+from typing import Type, TypeVar, cast
+from xml.etree import ElementTree as ET
 
 from .xml import Element, SubElement, find, findtext
 
 AES256 = "AES256"
 AWS_KMS = "aws:kms"
 
+A = TypeVar("A", bound="Rule")
+
 
 class Rule:
     """Server-side encryption rule. """
     __metaclass__ = ABCMeta
 
-    def __init__(self, sse_algorithm, kms_master_key_id=None):
+    def __init__(
+            self,
+            sse_algorithm: str,
+            kms_master_key_id: str | None = None,
+    ):
         self._sse_algorithm = sse_algorithm
         self._kms_master_key_id = kms_master_key_id
 
     @property
-    def sse_algorithm(self):
+    def sse_algorithm(self) -> str:
         """Get SSE algorithm."""
         return self._sse_algorithm
 
     @property
-    def kms_master_key_id(self):
+    def kms_master_key_id(self) -> str | None:
         """Get KMS master key ID."""
         return self._kms_master_key_id
 
     @classmethod
-    def new_sse_s3_rule(cls):
+    def new_sse_s3_rule(cls: Type[A]) -> A:
         """Create SSE-S3 rule."""
         return cls(AES256)
 
     @classmethod
-    def new_sse_kms_rule(cls, kms_master_key_id=None):
+    def new_sse_kms_rule(
+            cls: Type[A],
+            kms_master_key_id: str | None = None,
+    ) -> A:
         """Create new SSE-KMS rule."""
         return cls(AWS_KMS, kms_master_key_id)
 
     @classmethod
-    def fromxml(cls, element):
+    def fromxml(cls: Type[A], element: ET.Element) -> A:
         """Create new object with values from XML element."""
-        element = find(element, "ApplyServerSideEncryptionByDefault")
-        sse_algorithm = findtext(element, "SSEAlgorithm", True)
-        kms_master_key_id = findtext(element, "KMSMasterKeyID")
-        return cls(sse_algorithm, kms_master_key_id)
-
-    def toxml(self, element):
+        element = cast(
+            ET.Element,
+            find(element, "ApplyServerSideEncryptionByDefault", True),
+        )
+        return cls(
+            cast(str, findtext(element, "SSEAlgorithm", True)),
+            findtext(element, "KMSMasterKeyID"),
+        )
+
+    def toxml(self, element: ET.Element | None) -> ET.Element:
         """Convert to XML."""
+        if element is None:
+            raise ValueError("element must be provided")
         element = SubElement(element, "Rule")
         tag = SubElement(element, "ApplyServerSideEncryptionByDefault")
         SubElement(tag, "SSEAlgorithm", self._sse_algorithm)
@@ -72,26 +89,29 @@ def toxml(self, element):
         return element
 
 
+B = TypeVar("B", bound="SSEConfig")
+
+
 class SSEConfig:
     """server-side encryption configuration."""
 
-    def __init__(self, rule):
+    def __init__(self, rule: Rule):
         if not rule:
             raise ValueError("rule must be provided")
         self._rule = rule
 
     @property
-    def rule(self):
+    def rule(self) -> Rule:
         """Get rule."""
         return self._rule
 
     @classmethod
-    def fromxml(cls, element):
+    def fromxml(cls: Type[B], element: ET.Element) -> B:
         """Create new object with values from XML element."""
-        element = find(element, "Rule")
+        element = cast(ET.Element, find(element, "Rule", True))
         return cls(Rule.fromxml(element))
 
-    def toxml(self, element):
+    def toxml(self, element: ET.Element | None) -> ET.Element:
         """Convert to XML."""
         element = Element("ServerSideEncryptionConfiguration")
         self._rule.toxml(element)