normalize key bugfix in TM (#5024)

* fix normalize key method to not strip extra character when prefix is not immediately followed by separator in the key

* Pr comments
- normalizeKey take prefix as string
- added test cases
- javadoc

* changelog

* checkstyle

Author: L-Applin

.changes/next-release/bugfix-S3TransferManager-aae4592.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "S3 Transfer Manager",
+    "contributor": "",
+    "description": "Fix normalize key method to not strip extra character when prefix is not immediately followed by separator in the key."
+}

services-custom/s3-transfer-manager/src/main/java/software/amazon/awssdk/transfer/s3/internal/DirectoryHelperUtils.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.awssdk.transfer.s3.internal;
+
+import software.amazon.awssdk.annotations.SdkInternalApi;
+import software.amazon.awssdk.utils.StringUtils;
+import software.amazon.awssdk.utils.Validate;
+
+@SdkInternalApi
+final class DirectoryHelperUtils {
+
+    private DirectoryHelperUtils() {
+    }
+
+    /**
+     * If the prefix is not empty AND the key contains the delimiter, normalize the key by stripping the prefix from the key. If a
+     * delimiter is null (not provided by user), use "/" by default.
+     * For example: given a request with prefix = "notes/2021"  or
+     * "notes/2021/", delimiter = "/" and key = "notes/2021/1.txt", the normalized key should be "1.txt".
+     * If the prefix is not the full name of the folder, the folder name will be truncated. For example: given a request
+     * with prefix = "top-" , delimiter = "/" and key = "top-level/sub-folder/1.txt", the normalized key should be
+     * "level/sub-folder/1.txt"
+     */
+    static String normalizeKey(String prefix,
+                                      String key,
+                                      String delimiter) {
+        Validate.notNull(delimiter, "delimiter must not be null");
+
+        if (StringUtils.isEmpty(key) || StringUtils.isEmpty(prefix)) {
+            return key;
+        }
+
+        if (!key.startsWith(prefix)) {
+            return key;
+        }
+
+        if (!key.contains(delimiter)) {
+            return key;
+        }
+
+        String stripped = key.substring(prefix.length());
+        if (prefix.endsWith(delimiter) || !stripped.startsWith(delimiter)) {
+            return stripped;
+        }
+
+        return stripped.substring(1);
+    }
+
+}

services-custom/s3-transfer-manager/src/main/java/software/amazon/awssdk/transfer/s3/internal/DownloadDirectoryHelper.java

@@ -143,7 +143,7 @@ private Path determineDestinationPath(DownloadDirectoryRequest downloadDirectory
                                           S3Object s3Object) {
         FileSystem fileSystem = downloadDirectoryRequest.destination().getFileSystem();
         String delimiter = listRequest.delimiter() == null ? DEFAULT_DELIMITER : listRequest.delimiter();
-        String key = normalizeKey(listRequest, s3Object.key(), delimiter);
+        String key = DirectoryHelperUtils.normalizeKey(listRequest.prefix(), s3Object.key(), delimiter);
         String relativePath = getRelativePath(fileSystem, delimiter, key);
         Path destinationPath = downloadDirectoryRequest.destination().resolve(relativePath);
         validatePath(downloadDirectoryRequest.destination(), destinationPath, s3Object.key());
@@ -192,37 +192,6 @@ private CompletableFuture<CompletedFileDownload> doDownloadSingleFile(DownloadDi
         }
     }
 
-    /**
-     * If the prefix is not empty AND the key contains the delimiter, normalize the key by stripping the prefix from the key.
-     *
-     * If a delimiter is null (not provided by user), use "/" by default.
-     *
-     * For example: given a request with prefix = "notes/2021"  or "notes/2021/", delimiter = "/" and key = "notes/2021/1.txt",
-     * the normalized key should be "1.txt".
-     */
-    private static String normalizeKey(ListObjectsV2Request listObjectsRequest,
-                                       String key,
-                                       String delimiter) {
-        if (StringUtils.isEmpty(listObjectsRequest.prefix())) {
-            return key;
-        }
-
-        String prefix = listObjectsRequest.prefix();
-
-        if (!key.contains(delimiter)) {
-            return key;
-        }
-
-        String normalizedKey;
-
-        if (prefix.endsWith(delimiter)) {
-            normalizedKey = key.substring(prefix.length());
-        } else {
-            normalizedKey = key.substring(prefix.length() + delimiter.length());
-        }
-        return normalizedKey;
-
-    }
 
     private static String getRelativePath(FileSystem fileSystem, String delimiter, String key) {
         if (delimiter == null) {

services-custom/s3-transfer-manager/src/test/java/software/amazon/awssdk/transfer/s3/internal/DirectoryHelperUtilsTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.awssdk.transfer.s3.internal;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.util.Arrays;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
+import software.amazon.awssdk.services.s3.model.ListObjectsV2Request;
+
+class DirectoryHelperUtilsTest {
+
+    @ParameterizedTest
+    @MethodSource("arguments")
+    void testNormalizeKey(String prefix, String key, String expected) {
+        String normalized = DirectoryHelperUtils.normalizeKey(prefix, key, "/");
+        assertThat(normalized).isEqualTo(expected);
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"/", "//", "\\", "|", "delim"})
+    void testDelimiter(String delimiter) {
+        String prefix = String.format("notes%s2021%s", delimiter, delimiter);
+        String key = String.format("notes%s2021%s1.txt", delimiter, delimiter);
+        String normalized = DirectoryHelperUtils.normalizeKey(prefix, key, delimiter);
+        assertThat(normalized).isEqualTo("1.txt");
+    }
+
+    private static List<Arguments> arguments() {
+        return Arrays.asList(
+            arg(null, "no-delim", "no-delim"),
+            arg("", "no-delim", "no-delim"),
+            arg("", "delim/with/separator", "delim/with/separator"),
+            arg("no-delim", "", ""),
+            arg("no-delim", "no-delim", "no-delim"),
+            arg("delim", "delim/", ""),
+            arg("prefix", "not-in-key", "not-in-key"),
+            arg("notes/2021", "notes/2021/1.txt", "1.txt"),
+            arg("notes/2021/", "notes/2021/1.txt", "1.txt"),
+            arg("top-", "top-level/sub-folder/1.txt", "level/sub-folder/1.txt"),
+            arg("someInner", "someInnerFolder/another/file1.txt", "Folder/another/file1.txt"),
+            arg("someInner", "someInnerF/another/file1.txt", "F/another/file1.txt"),
+            arg("someInner", "someInner/another/file1.txt", "another/file1.txt"),
+            arg("someInner/a", "someInner/another/file1.txt", "nother/file1.txt")
+        );
+    }
+
+    private static Arguments arg(String prefix, String key, String expected) {
+        return Arguments.of(prefix, key, expected);
+    }
+
+}