Implement artifact download functionality in Flutter web app

Added the downloadArtifact method to the ChatService class, enabling the download of artifacts in the Flutter web application. The function uses the dart:html package to trigger a browser-based file download, allowing users to save artifacts locally. This implementation complements the existing REST API and enhances the user experience.

frontend/lib/services/chat_service.dart

@@ -1,6 +1,8 @@
 import 'dart:io';
+import 'dart:typed_data';
 import 'package:auto_gpt_flutter_client/models/step_request_body.dart';
 import 'package:auto_gpt_flutter_client/utils/rest_api_utility.dart';
+import 'dart:html' as html;
 
 /// Service class for performing chat-related operations.
 class ChatService {
@@ -63,8 +65,26 @@ class ChatService {
   ///
   /// [taskId] is the ID of the task.
   /// [artifactId] is the ID of the artifact.
-  Future<Map<String, dynamic>> downloadArtifact(
-      String taskId, String artifactId) async {
-    return Future.value({'status': 'Not implemented yet'});
+  Future<void> downloadArtifact(String taskId, String artifactId) async {
+    try {
+      final Uint8List bytes =
+          await api.getBinary('agent/tasks/$taskId/artifacts/$artifactId');
+
+      // Create a blob from the Uint8List
+      final blob = html.Blob([bytes]);
+
+      // Generate a URL from the Blob
+      final url = html.Url.createObjectUrlFromBlob(blob);
+
+      // Create an anchor HTML element
+      final anchor = html.AnchorElement(href: url)
+        ..setAttribute("download", "artifact_$artifactId")
+        ..click();
+
+      // Cleanup: Revoke the object URL
+      html.Url.revokeObjectUrl(url);
+    } catch (e) {
+      throw Exception('An error occurred while downloading the artifact: $e');
+    }
   }
 }

frontend/lib/utils/rest_api_utility.dart

@@ -1,4 +1,5 @@
 import 'dart:convert';
+import 'dart:typed_data';
 import 'package:http/http.dart' as http;
 
 class RestApiUtility {
@@ -32,4 +33,19 @@ class RestApiUtility {
       throw Exception('Failed to post data');
     }
   }
+
+  Future<Uint8List> getBinary(String endpoint) async {
+    final response = await http.get(
+      Uri.parse('$_baseUrl/$endpoint'),
+      headers: {"Content-Type": "application/octet-stream"},
+    );
+
+    if (response.statusCode == 200) {
+      return response.bodyBytes;
+    } else if (response.statusCode == 404) {
+      throw Exception('Resource not found');
+    } else {
+      throw Exception('Failed to load binary data');
+    }
+  }
 }

frontend/pubspec.lock

@@ -41,6 +41,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.17.2"
+  csslib:
+    dependency: transitive
+    description:
+      name: csslib
+      sha256: "706b5707578e0c1b4b7550f64078f0a0f19dec3f50a178ffae7006b0a9ca58fb"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -112,6 +120,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.7.0"
+  html:
+    dependency: "direct main"
+    description:
+      name: html
+      sha256: "3a7812d5bcd2894edf53dfaf8cd640876cf6cef50a8f238745c8b8120ea74d3a"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.15.4"
   http:
     dependency: "direct main"
     description:

frontend/pubspec.yaml

@@ -39,6 +39,7 @@ dependencies:
   provider: ^6.0.5
   http: ^1.1.0
   shared_preferences: ^2.2.1
+  dart:html: any
 
 dev_dependencies:
   flutter_test: