fix s3 downloads resulting in flat folder structure

Signed-off-by: Matt Wise <wsmatth@amazon.com>

packages/backend-common/src/reading/AwsS3UrlReader.ts

@@ -46,6 +46,7 @@ import {
 import { AbortController } from '@aws-sdk/abort-controller';
 import { ReadUrlResponseFactory } from './ReadUrlResponseFactory';
 import { Readable } from 'stream';
+import { relative } from 'path/posix';
 
 export const DEFAULT_REGION = 'us-east-1';
 
@@ -345,7 +346,7 @@ export class AwsS3UrlReader implements UrlReader {
 
         responses.push({
           data: s3ObjectData,
-          path: String(allObjects[i]),
+          path: relative(path, String(allObjects[i])),
           lastModifiedAt: response?.LastModified ?? undefined,
         });
       }

packages/backend-common/src/reading/tree/ReadableArrayResponse.ts

@@ -15,7 +15,7 @@
  */
 
 import concatStream from 'concat-stream';
-import platformPath, { basename } from 'path';
+import platformPath, { dirname } from 'path';
 
 import getRawBody from 'raw-body';
 import fs from 'fs-extra';
@@ -96,12 +96,9 @@ export class ReadableArrayResponse implements ReadTreeResponse {
 
     for (let i = 0; i < this.stream.length; i++) {
       if (!this.stream[i].path.endsWith('/')) {
-        await pipeline(
-          this.stream[i].data,
-          fs.createWriteStream(
-            platformPath.join(dir, basename(this.stream[i].path)),
-          ),
-        );
+        const filePath = platformPath.join(dir, this.stream[i].path);
+        await fs.mkdir(dirname(filePath), { recursive: true });
+        await pipeline(this.stream[i].data, fs.createWriteStream(filePath));
       }
     }