sending progress to ui with very epic animated upload progress

lib/main.dart

@@ -11,6 +11,7 @@ class MainApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
+      debugShowCheckedModeBanner: false,
       theme: ThemeData(
         useMaterial3: true,
         colorSchemeSeed: Colors.teal,

lib/sftp_explorer.dart

@@ -21,6 +21,8 @@ class _SftpExplorerState extends State<SftpExplorer> {
   bool _isLoading = true;
   late List<SftpName> _dirContents;
 
+  double? _progress;
+  
   @override
   void initState() {
     super.initState();
@@ -45,7 +47,29 @@ class _SftpExplorerState extends State<SftpExplorer> {
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
+        toolbarHeight: 75,
         title: Text('Explorer'),
+        elevation: 2,
+        actionsPadding: EdgeInsets.only(right: 20),
+        actions: [
+          if (_progress != null)
+          Stack(
+            alignment: Alignment.center,
+            children: [
+              TweenAnimationBuilder<double>(
+                tween: Tween(begin: 0, end: _progress),
+                duration: Duration(milliseconds: 300),
+                builder: (context, value, _) => CircularProgressIndicator(strokeWidth: 3, value: value,)
+              ),
+              IconButton(
+                onPressed: () {
+
+                },
+                icon: Icon(Icons.upload)
+              ),
+            ]
+          ),
+        ],
       ),
       floatingActionButton: _buildFABs(context),
       body: _isLoading ? Center(child: CircularProgressIndicator()) : ListView.builder(
@@ -234,7 +258,18 @@ class _SftpExplorerState extends State<SftpExplorer> {
               final files = await openFiles();
               filePaths = files.map((file) => file.path).toList();
             }
-            await widget.sftpWorker.uploadFiles(widget.path, filePaths);
+            try {
+              await for (final progress in widget.sftpWorker.uploadFiles(widget.path, filePaths)) {
+                print(progress);
+                setState(() => _progress = progress);
+              }
+            }
+            catch (e) {
+              if (context.mounted) {
+                ScaffoldMessenger.of(context).showSnackBar(_buildErrorSnackBar(context, e.toString()));
+              }
+            }
+            setState(() => _progress = null);
             _listDir();
           },
           child: Icon(Icons.upload),

lib/sftp_worker.dart

@@ -24,7 +24,7 @@ class SftpWorker {
 
   final ReceivePort _responses;
   final SendPort _commands;
-  final Map<int, Completer<Object>> _activeRequests = {};
+  final Map<int, dynamic> _activeRequests = {};
   int _idCounter = 0;
 
   SftpWorker._(this._responses, this._commands) {
@@ -98,24 +98,31 @@ class SftpWorker {
                 '$path${basename(filePath)}',
                 mode: SftpFileOpenMode.create | SftpFileOpenMode.write | SftpFileOpenMode.exclusive
               );
+              bool timeout = true;
               await remoteFile.write(
                 file.openRead().cast(),
                 onProgress: (progress) {
-                  print(progress/fileSize);
+                  if (timeout) {
+                    timeout = false;
+                    sendPort.send((id, progress/fileSize));
+                    Future.delayed(Duration(seconds: 2), () => timeout = true);
+                  }
                 }
               );
             }
             on SftpStatusError catch (e) {
               sendPort.send((id, RemoteError(e.message, '')));
             }
+            sendPort.send((id, 1.0));
           }
-          sendPort.send((id, 0));
       }
     });
   }
 
   void _sftpResponseHandler(dynamic message) {
     final (int id, Object response) = message;
+
+    if (_activeRequests[id] is Completer) {
       final completer = _activeRequests.remove(id)!;
 
       if (response is RemoteError) {
@@ -125,6 +132,20 @@ class SftpWorker {
         completer.complete(response);
       }
     }
+    else if (_activeRequests[id] is StreamController) {
+      final controller = _activeRequests[id] as StreamController;
+      if (response is RemoteError) {
+        controller.addError(response);
+      }
+      else {
+        controller.add(response);
+        if (response == 1) {
+          controller.close();
+          _activeRequests.remove(id);
+        }
+      }
+    }
+  }
 
   
   Future<List<SftpName>> listdir(String path) async {
@@ -136,12 +157,12 @@ class SftpWorker {
   }
 
   
-  Future<void> uploadFiles(String path, List<String> filePaths) async {
-    final completer = Completer<Object>.sync();
+  Stream<double> uploadFiles(String path, List<String> filePaths) {
+    final controller = StreamController<double>();
     final id = _idCounter++;
-    _activeRequests[id] = completer;
+    _activeRequests[id] = controller;
     _commands.send((id, UploadFiles(path, filePaths)));
-    await completer.future;
+    return controller.stream;
   }