fix: resolve file content type based on file extension

src/main/java/com/epam/aidial/core/storage/BlobStorage.java

@@ -23,6 +23,7 @@
 import org.jclouds.io.ContentMetadata;
 import org.jclouds.io.ContentMetadataBuilder;
 import org.jclouds.io.payloads.BaseMutableContentMetadata;
+import org.jclouds.s3.domain.ObjectMetadataBuilder;
 
 import java.io.Closeable;
 import java.util.List;
@@ -32,6 +33,11 @@
 @Slf4j
 public class BlobStorage implements Closeable {
 
+    // S3 implementation do not return a blob content type without additional head request.
+    // To avoid additional request for each blob in the listing we try to recognize blob content type by its extension.
+    // Default value is binary/octet-stream, see org.jclouds.s3.domain.ObjectMetadataBuilder
+    private static final String DEFAULT_CONTENT_TYPE = ObjectMetadataBuilder.create().build().getContentMetadata().getContentType();
+
     private final BlobStoreContext storeContext;
     private final BlobStore blobStore;
     private final String bucketName;
@@ -171,8 +177,14 @@ private static FileMetadataBase buildFileMetadata(ResourceDescription resource,
                 resource.getBucketLocation(), metadata.getName());
 
         return switch (metadata.getType()) {
-            case BLOB -> new FileMetadata(resultResource, metadata.getSize(),
-                    ((BlobMetadata) metadata).getContentMetadata().getContentType());
+            case BLOB -> {
+                String blobContentType = ((BlobMetadata) metadata).getContentMetadata().getContentType();
+                if (blobContentType != null && blobContentType.equals(DEFAULT_CONTENT_TYPE)) {
+                    blobContentType = BlobStorageUtil.getContentType(metadata.getName());
+                }
+
+                yield new FileMetadata(resultResource, metadata.getSize(), blobContentType);
+            }
             case FOLDER, RELATIVE_PATH -> new FolderMetadata(resultResource);
             case CONTAINER -> throw new IllegalArgumentException("Can't list container");
         };

src/test/java/com/epam/aidial/core/FileApiTest.java

@@ -389,6 +389,72 @@ public void testListFileWithFolder(Vertx vertx, VertxTestContext context) {
         });
     }
 
+    @Test
+    public void testListFileWithDefaultContentType(Vertx vertx, VertxTestContext context) {
+        Checkpoint checkpoint = context.checkpoint(3);
+        WebClient client = WebClient.create(vertx);
+
+        FolderMetadata emptyFolderResponse = new FolderMetadata("7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt",
+                null, null, "7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/", List.of());
+
+        FileMetadata expectedFileMetadata1 = new FileMetadata("7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt",
+                "image.png", null, "7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/image.png", 17, "binary/octet-stream");
+
+        FileMetadata expectedImageMetadata = new FileMetadata("7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt",
+                "image.png", null, "7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/image.png", 17, "image/png");
+        FolderMetadata expectedRootFolderMetadata = new FolderMetadata("7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt",
+                null, null, "7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/",
+                List.of(expectedImageMetadata));
+
+        Future.succeededFuture().compose((mapper) -> {
+            Promise<Void> promise = Promise.promise();
+            // verify no files
+            client.get(serverPort, "localhost", "/v1/files/metadata/7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/")
+                    .putHeader("Api-key", "proxyKey2")
+                    .as(BodyCodec.json(FolderMetadata.class))
+                    .send(context.succeeding(response -> {
+                        context.verify(() -> {
+                            assertEquals(200, response.statusCode());
+                            assertEquals(emptyFolderResponse, response.body());
+                            checkpoint.flag();
+                            promise.complete();
+                        });
+                    }));
+
+            return promise.future();
+        }).compose((mapper) -> {
+            Promise<Void> promise = Promise.promise();
+            // upload test file1
+            client.put(serverPort, "localhost", "/v1/files/7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/image.png")
+                    .putHeader("Api-key", "proxyKey2")
+                    .as(BodyCodec.json(FileMetadata.class))
+                    .sendMultipartForm(generateMultipartForm("filename", TEST_FILE_CONTENT, "binary/octet-stream"),
+                            context.succeeding(response -> {
+                                context.verify(() -> {
+                                    assertEquals(200, response.statusCode());
+                                    assertEquals(expectedFileMetadata1, response.body());
+                                    checkpoint.flag();
+                                    promise.complete();
+                                });
+                            })
+                    );
+
+            return promise.future();
+        }).andThen((result) -> {
+            // verify uploaded files can be listed
+            client.get(serverPort, "localhost", "/v1/files/metadata/7G9WZNcoY26Vy9D7bEgbv6zqbJGfyDp9KZyEbJR4XMZt/")
+                    .putHeader("Api-key", "proxyKey2")
+                    .as(BodyCodec.string())
+                    .send(context.succeeding(response -> {
+                        context.verify(() -> {
+                            assertEquals(200, response.statusCode());
+                            assertEquals(ProxyUtil.MAPPER.writeValueAsString(expectedRootFolderMetadata), response.body());
+                            checkpoint.flag();
+                        });
+                    }));
+        });
+    }
+
     @Test
     public void testFileDelete(Vertx vertx, VertxTestContext context) {
         Checkpoint checkpoint = context.checkpoint(3);