From 349353edaa261a252aa9b8aa45ed2989634a3bee Mon Sep 17 00:00:00 2001
From: Bert Blommers <info@bertblommers.nl>
Date: Thu, 7 Mar 2024 19:46:30 +0000
Subject: [PATCH] Techdebt: Move S3 CompleteMultipartUpload to the backend
 (#7437)

---
 moto/s3/models.py    | 30 ++++++++++++++++++++++++++++--
 moto/s3/responses.py | 36 ++++++------------------------------
 2 files changed, 34 insertions(+), 32 deletions(-)

diff --git a/moto/s3/models.py b/moto/s3/models.py
index cf5643d03aa..14bd40c5c1e 100644
--- a/moto/s3/models.py
+++ b/moto/s3/models.py
@@ -2423,13 +2423,39 @@ def create_multipart_upload(
 
     def complete_multipart_upload(
         self, bucket_name: str, multipart_id: str, body: Iterator[Tuple[int, str]]
-    ) -> Tuple[FakeMultipart, bytes, str, Optional[str]]:
+    ) -> Optional[FakeKey]:
         bucket = self.get_bucket(bucket_name)
         multipart = bucket.multiparts[multipart_id]
         value, etag, checksum = multipart.complete(body)
         if value is not None:
             del bucket.multiparts[multipart_id]
-        return multipart, value, etag, checksum
+
+        if value is None:
+            return None
+
+        key = self.put_object(
+            bucket_name,
+            multipart.key_name,
+            value,
+            storage=multipart.storage,
+            etag=etag,
+            multipart=multipart,
+            encryption=multipart.sse_encryption,
+            kms_key_id=multipart.kms_key_id,
+        )
+        key.set_metadata(multipart.metadata)
+
+        if checksum:
+            key.checksum_algorithm = multipart.metadata.get("x-amz-checksum-algorithm")
+            key.checksum_value = checksum
+
+        self.put_object_tagging(key, multipart.tags)
+        self.put_object_acl(
+            bucket_name=bucket_name,
+            key_name=key.name,
+            acl=multipart.acl,
+        )
+        return key
 
     def get_all_multiparts(self, bucket_name: str) -> Dict[str, FakeMultipart]:
         bucket = self.get_bucket(bucket_name)
diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 65c31081438..629df1c4ef1 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -2245,37 +2245,13 @@ def _key_response_post(
         if query.get("uploadId"):
             multipart_id = query["uploadId"][0]
 
-            multipart, value, etag, checksum = self.backend.complete_multipart_upload(
+            key = self.backend.complete_multipart_upload(
                 bucket_name, multipart_id, self._complete_multipart_body(body)
             )
-            if value is None:
+            if key is None:
                 return 400, {}, ""
 
             headers: Dict[str, Any] = {}
-            key = self.backend.put_object(
-                bucket_name,
-                multipart.key_name,
-                value,
-                storage=multipart.storage,
-                etag=etag,
-                multipart=multipart,
-                encryption=multipart.sse_encryption,
-                kms_key_id=multipart.kms_key_id,
-            )
-            key.set_metadata(multipart.metadata)
-
-            if checksum:
-                key.checksum_algorithm = multipart.metadata.get(
-                    "x-amz-checksum-algorithm"
-                )
-                key.checksum_value = checksum
-
-            self.backend.put_object_tagging(key, multipart.tags)
-            self.backend.put_object_acl(
-                bucket_name=bucket_name,
-                key_name=key.name,
-                acl=multipart.acl,
-            )
 
             template = self.response_template(S3_MULTIPART_COMPLETE_RESPONSE)
             if key.version_id:
@@ -2299,12 +2275,12 @@ def _key_response_post(
             es = minidom.parseString(body).getElementsByTagName("Days")
             days = es[0].childNodes[0].wholeText
             key = self.backend.get_object(bucket_name, key_name)  # type: ignore
-            if key.storage_class not in ARCHIVE_STORAGE_CLASSES:
-                raise InvalidObjectState(storage_class=key.storage_class)
+            if key.storage_class not in ARCHIVE_STORAGE_CLASSES:  # type: ignore
+                raise InvalidObjectState(storage_class=key.storage_class)  # type: ignore
             r = 202
-            if key.expiry_date is not None:
+            if key.expiry_date is not None:  # type: ignore
                 r = 200
-            key.restore(int(days))
+            key.restore(int(days))  # type: ignore
             return r, {}, ""
         elif "select" in query:
             request = xmltodict.parse(body)["SelectObjectContentRequest"]