Fix error response formatting issue and NullPointerException when getting a fileName with a query param

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/impl/FileDownloaderServiceProvider.java

@@ -122,7 +122,10 @@ public class FileDownloaderServiceProvider {
                 }
 
                 FileMetaEntry fileMetaEntry = new FileMetaEntry();
-                fileMetaEntry.setSize(Long.parseLong(Objects.requireNonNull(response.header("Content-Length"))));
+                String contentLength = response.header("Content-Length");
+                if (contentLength != null) {
+                    fileMetaEntry.setSize(Long.parseLong(contentLength));
+                }
                 fileMetaEntry.setFileName(fileNameSegments[0]);
                 fileMetaEntry.setExtension(fileNameSegments[1]);
                 return fileMetaEntry;
@@ -132,9 +135,21 @@ public class FileDownloaderServiceProvider {
         }
 
         /**
-         * Extracting file name segments by parsing the URL
-         * @param url Remote URL to extract file name segments
-         * @return Array containing file name segments or null when failed to extract
+         * Extracts file name segments (name and extension) by parsing the given URL.
+         * This method handles two types of URL formats:
+         * - If the URL includes a query parameter in the format `?fileName=`, the file name
+         *   is extracted from this query parameter (ex: when referencing an existing
+         *   screenshot or icon from the main release)
+         * - If the URL does not have the `fileName` query parameter, the method attempts to
+         *   extract the file name from the URL path. (ex: this applies to cases where new files are
+         *   uploaded, and only a path-based URL is provided)
+         * After locating the file name (from either the query parameter or path), the method
+         * splits the name into segments based on the last dot (`.`), returning the base name and
+         * extension as a two-element array. If file name cannot be extracted, `null` is returned.
+         *
+         * @param url Remote URL to extract file name segments from, which may contain a file name
+         *            as either a query parameter (`fileName=...`) or in the path.
+         * @return An array containing the file name and extension segments, or null if extraction fails.
          */
         public static String[] extractFileNameSegmentsFromUrl(URL url) {
             if (url == null) {
@@ -143,24 +158,35 @@ public class FileDownloaderServiceProvider {
                 }
                 return null;
             }
-
-            String []urlSegments = url.toString().split("/");
-            if (urlSegments.length < 1) {
+            String fullQualifiedName = null;
+            String query = url.getQuery();
+            if (query != null && query.startsWith("fileName=")) {
+                String[] queryParts = query.split("=", 2);
+                if (queryParts.length > 1 && !queryParts[1].isEmpty()) {
+                    fullQualifiedName = queryParts[1];
+                }
+            }
+            if (fullQualifiedName == null) {
+                String[] urlSegments = url.getPath().split("/");
+                if (urlSegments.length > 0) {
+                    fullQualifiedName = urlSegments[urlSegments.length - 1];
+                }
+            }
+            if (fullQualifiedName != null) {
+                String[] fileNameSegments = fullQualifiedName.split("\\.(?=[^.]+$)");
+                if (fileNameSegments.length == 2) {
+                    return fileNameSegments;
+                } else {
                     if (log.isDebugEnabled()) {
-                    log.debug("Cannot determine the file name for the remote file");
+                        log.debug("Error encountered when constructing file name");
                     }
-                return null;
                 }
-
-            String fullQualifiedName = urlSegments[urlSegments.length - 1];
-            String []fileNameSegments = fullQualifiedName.split("\\.(?=[^.]+$)");
-            if (fileNameSegments.length != 2) {
+            } else {
                 if (log.isDebugEnabled()) {
                     log.debug("Error encountered when constructing file name");
                 }
-                return null;
             }
-            return fileNameSegments;
+            return null;
         }
 
         /**

components/application-mgt/io.entgra.device.mgt.core.application.mgt.core/src/main/java/io/entgra/device/mgt/core/application/mgt/core/util/FileTransferServiceHelperUtil.java

@@ -183,6 +183,15 @@ public class FileTransferServiceHelperUtil {
             return fileDescriptorResolvedFromRelease;
         }
 
+        String file = urlPathSegments[urlPathSegments.length - 1];
+        String query = downloadUrl.getQuery();
+        if (query != null && query.startsWith("fileName=")) {
+            String[] queryParts = query.split("=", 2);
+            if (queryParts.length > 1 && !queryParts[1].isEmpty()) {
+                file = queryParts[1];
+            }
+        }
+
         if (urlPathSegments.length < 2) {
             if (log.isDebugEnabled()) {
                 log.debug("URL patch segments contain less than 2 segments");
@@ -190,7 +199,6 @@ public class FileTransferServiceHelperUtil {
             return null;
         }
 
-        String file = urlPathSegments[urlPathSegments.length - 1];
         String artifactHolder = urlPathSegments[urlPathSegments.length - 2];
         try {
             FileDescriptor fileDescriptor = new FileDescriptor();

components/ui-request-interceptor/io.entgra.device.mgt.core.ui.request.interceptor/src/main/java/io/entgra/device/mgt/core/ui/request/interceptor/beans/ErrorResponse.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2018 - 2024, Entgra (Pvt) Ltd. (http://www.entgra.io) All Rights Reserved.
+ *
+ * Entgra (Pvt) Ltd. licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License 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 io.entgra.device.mgt.core.ui.request.interceptor.beans;
+
+public class ErrorResponse {
+    private int code;
+    private String data;
+    private int status;
+
+    public ErrorResponse(int code, String data, int status) {
+        this.code = code;
+        this.data = data;
+        this.status = status;
+    }
+
+    public int getCode() {
+        return code;
+    }
+
+    public void setCode(int code) {
+        this.code = code;
+    }
+
+    public String getData() {
+        return data;
+    }
+
+    public void setData(String data) {
+        this.data = data;
+    }
+
+    public int getStatus() {
+        return status;
+    }
+
+    public void setStatus(int status) {
+        this.status = status;
+    }
+}
+

components/ui-request-interceptor/io.entgra.device.mgt.core.ui.request.interceptor/src/main/java/io/entgra/device/mgt/core/ui/request/interceptor/util/HandlerUtil.java

@@ -20,17 +20,16 @@ package io.entgra.device.mgt.core.ui.request.interceptor.util;
 
 import com.fasterxml.jackson.core.JsonFactory;
 import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.DeserializationFeature;
-import com.fasterxml.jackson.databind.JsonMappingException;
 import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ArrayNode;
-import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.node.TextNode;
 import com.google.gson.Gson;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonParser;
 import io.entgra.device.mgt.core.ui.request.interceptor.beans.AuthData;
+import io.entgra.device.mgt.core.ui.request.interceptor.beans.ErrorResponse;
 import io.entgra.device.mgt.core.ui.request.interceptor.cache.LoginCache;
 import org.apache.commons.fileupload.FileItem;
 import org.apache.commons.fileupload.FileUploadException;
@@ -227,16 +226,37 @@ public class HandlerUtil {
             proxyResponse.setExecutorResponse(HandlerConstants.EXECUTOR_EXCEPTION_PREFIX + HandlerUtil
                     .getStatusKey(HandlerConstants.INTERNAL_ERROR_CODE));
         }
+        JsonNode dataNode = proxyResponse.getData();
+        String responseData = extractDataAsString(dataNode);
         resp.setStatus(proxyResponse.getCode());
         resp.setContentType(ContentType.APPLICATION_JSON.getMimeType());
         resp.setCharacterEncoding(Consts.UTF_8.name());
 
         proxyResponse.setExecutorResponse(null);
+        proxyResponse.setData(null);
+        ErrorResponse errorResponse = new ErrorResponse(
+                proxyResponse.getCode(),
+                responseData,
+                proxyResponse.getStatus()
+        );
         try (PrintWriter writer = resp.getWriter()) {
-            writer.write(gson.toJson(proxyResponse));
+            writer.write(gson.toJson(errorResponse));
         }
     }
 
+    /**
+     * Extracts a string representation from the given JsonNode.
+     *
+     * @param dataNode the JsonNode from which to extract the string representation (can be null).
+     * @return the string representation of the JsonNode, or null if the dataNode is null.
+     */
+    private static String extractDataAsString(JsonNode dataNode) {
+        if (dataNode == null) {
+            return null;
+        }
+        return dataNode.isTextual() ? dataNode.asText() : dataNode.toString();
+    }
+
     /**
      * Handle error requests with custom error codes.
      *
@@ -772,9 +792,7 @@ public class HandlerUtil {
             try {
                 finalNode = objectMapper.readTree(content);
             } catch (JsonProcessingException e) {
-                ObjectNode objectNode = objectMapper.createObjectNode();
-                objectNode.put("message", content);
-                finalNode = objectMapper.valueToTree(objectNode);
+                finalNode = new TextNode(content);
             }
         }
         return finalNode;