fix after test

src/main/java/ru/soune/nocopy/dto/file/FileExtensionResponse.java

@@ -0,0 +1,17 @@
+package ru.soune.nocopy.dto.file;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import lombok.Builder;
+import lombok.Data;
+
+import java.util.List;
+
+@Data
+@Builder
+public class FileExtensionResponse {
+    @JsonProperty("file_extension")
+    private List<String> extension;
+
+    @JsonProperty("count")
+    private Integer count;
+}

src/main/java/ru/soune/nocopy/handler/FileUploadHandler.java

@@ -44,6 +44,8 @@ public class FileUploadHandler implements RequestHandler {
                     return handleInitUpload(request, fileRequest);
                 case "file_types":
                     return handleGetFileTypes(request);
+                case "file_extension":
+                    return handleGetFileExtensions(fileRequest, request);
                 case "chunks":
                     return handleGetChunkStatus(request, fileRequest);
                 case "cancel":
@@ -243,4 +245,23 @@ public class FileUploadHandler implements RequestHandler {
                     "Failed to get file types", null);
         }
     }
+
+    private BaseResponse handleGetFileExtensions(FileUploadRequest fileRequest, BaseRequest request) {
+        try {
+            FileType fileType = FileType.valueOf(fileRequest.getFileType().toUpperCase());
+            List<String> allowedExtensions = fileType.getAllowedExtensions();
+
+            FileExtensionResponse response = FileExtensionResponse.builder()
+                    .extension(allowedExtensions)
+                    .count(allowedExtensions.size())
+                    .build();
+
+            return new BaseResponse(request.getMsgId(), MessageCode.SUCCESS.getCode(),
+                    MessageCode.SUCCESS.getDescription(), response);
+        } catch (Exception e) {
+            log.error("Error getting file extensions", e);
+            return new BaseResponse(request.getMsgId(), MessageCode.FILE_UPLOAD_ERROR.getCode(),
+                    "Failed to get file extensions", null);
+        }
+    }
 }