Add a cancel button in Connect

app/lib/bloc/app_password_exchange.dart

@@ -3,7 +3,8 @@ import 'dart:io';
 
 import 'package:bloc/bloc.dart';
 import 'package:logging/logging.dart';
-
+import 'package:nc_photos/account.dart';
+import 'package:nc_photos/ci_string.dart';
 import 'package:nc_photos/api/api_util.dart' as api_util;
 import 'package:nc_photos/exception.dart';
 
@@ -38,6 +39,13 @@ class AppPasswordExchangeBlocPoll extends AppPasswordExchangeBlocEvent {
   final api_util.InitiateLoginPollOptions pollOptions;
 }
 
+class AppPasswordExchangeBlocCancel extends AppPasswordExchangeBlocEvent {
+  const AppPasswordExchangeBlocCancel();
+
+  @override
+  String toString() => "AppPasswordExchangeBlocCancel {}";
+}
+
 class _AppPasswordExchangeBlocAppPwReceived
     extends AppPasswordExchangeBlocEvent {
   const _AppPasswordExchangeBlocAppPwReceived(this.appPasswordResponse);
@@ -113,6 +121,17 @@ class AppPasswordExchangeBlocFailure extends AppPasswordExchangeBlocState {
   final dynamic exception;
 }
 
+class AppPasswordExchangeBlocResult extends AppPasswordExchangeBlocState {
+  const AppPasswordExchangeBlocResult(this.result);
+
+  @override
+  String toString() => "AppPasswordExchangeBlocResult {"
+      "result: $result, "
+      "}";
+
+  final Account? result;
+}
+
 /// Business Logic Component (BLoC) which handles the App password exchange.
 ///
 /// The flow followed by this component is described in the Nextcloud documentation under
@@ -136,6 +155,10 @@ class AppPasswordExchangeBloc
   Future<void> _onEvent(AppPasswordExchangeBlocEvent event,
       Emitter<AppPasswordExchangeBlocState> emit) async {
     _log.info("[_onEvent] $event");
+    if (_isCanceled) {
+      _log.fine("[_onEvent] canceled = true, ignore event");
+      return;
+    }
     if (event is AppPasswordExchangeBlocInitiateLogin) {
       await _onEventInitiateLogin(event, emit);
     } else if (event is AppPasswordExchangeBlocPoll) {
@@ -144,6 +167,8 @@ class AppPasswordExchangeBloc
       await _onEventAppPasswordReceived(event, emit);
     } else if (event is _AppPasswordExchangeBlocAppPwFailed) {
       await _onEventAppPasswordFailure(event, emit);
+    } else if (event is AppPasswordExchangeBlocCancel) {
+      await _onEventCancel(event, emit);
     }
   }
 
@@ -191,7 +216,9 @@ class AppPasswordExchangeBloc
       }
     } catch (e, stacktrace) {
       _log.shout(
-          "[_pollAppPasswordStreamListener] Failed while polling for password", e, stacktrace);
+          "[_pollAppPasswordStreamListener] Failed while polling for password",
+          e,
+          stacktrace);
       add(_AppPasswordExchangeBlocAppPwFailed(e));
     }
   }
@@ -200,7 +227,17 @@ class AppPasswordExchangeBloc
       _AppPasswordExchangeBlocAppPwReceived ev,
       Emitter<AppPasswordExchangeBlocState> emit) async {
     try {
-      emit(AppPasswordExchangeBlocAppPwSuccess(ev.appPasswordResponse));
+      final response = ev.appPasswordResponse;
+      final account = Account(
+        Account.newId(),
+        response.server.scheme,
+        response.server.authority,
+        response.loginName.toCi(),
+        response.loginName,
+        response.appPassword,
+        [""],
+      );
+      emit(AppPasswordExchangeBlocResult(account));
     } catch (e, stacktrace) {
       _log.shout(
           "[_onEventAppPasswordReceived] Failed while exchanging password",
@@ -217,6 +254,13 @@ class AppPasswordExchangeBloc
     emit(AppPasswordExchangeBlocFailure(ev.exception));
   }
 
+  Future<void> _onEventCancel(AppPasswordExchangeBlocCancel ev,
+      Emitter<AppPasswordExchangeBlocState> emit) async {
+    await _pollPasswordSubscription?.cancel();
+    _isCanceled = true;
+    emit(const AppPasswordExchangeBlocResult(null));
+  }
+
   @override
   Future<void> close() {
     _pollPasswordSubscription?.cancel();
@@ -228,4 +272,5 @@ class AppPasswordExchangeBloc
 
   StreamSubscription<Future<api_util.AppPasswordResponse>>?
       _pollPasswordSubscription;
+  bool _isCanceled = false;
 }

app/lib/widget/connect.dart

@@ -92,20 +92,48 @@ class _ConnectState extends State<Connect> {
   }
 
   Widget _buildContent(BuildContext context) {
-    return Padding(
-      padding: const EdgeInsets.symmetric(horizontal: 16),
-      child: Center(
+    return Center(
+      child: Container(
+        constraints: BoxConstraints(
+          maxWidth: Theme.of(context).widthLimitedContentMaxWidth,
+        ),
         child: Column(
-          crossAxisAlignment: CrossAxisAlignment.center,
-          mainAxisAlignment: MainAxisAlignment.center,
           children: [
-            const CloudProgressIndicator(size: 192),
-            const SizedBox(height: 16),
-            Text(
-              L10n.global().connectingToServer2,
-              textAlign: TextAlign.center,
-              style: Theme.of(context).textTheme.titleLarge,
-            )
+            Expanded(
+              child: Padding(
+                padding: const EdgeInsets.symmetric(horizontal: 16),
+                child: Column(
+                  mainAxisSize: MainAxisSize.min,
+                  mainAxisAlignment: MainAxisAlignment.center,
+                  children: [
+                    const CloudProgressIndicator(size: 192),
+                    const SizedBox(height: 16),
+                    Text(
+                      L10n.global().connectingToServer2,
+                      textAlign: TextAlign.center,
+                      style: Theme.of(context).textTheme.titleLarge,
+                    ),
+                  ],
+                ),
+              ),
+            ),
+            Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
+              child: Row(
+                mainAxisAlignment: MainAxisAlignment.start,
+                children: [
+                  TextButton(
+                    onPressed: () {
+                      _bloc.add(const AppPasswordExchangeBlocCancel());
+                    },
+                    child: Text(
+                      MaterialLocalizations.of(context).cancelButtonLabel,
+                      style: const TextStyle(color: Colors.white),
+                    ),
+                  ),
+                ],
+              ),
+            ),
           ],
         ),
       ),
@@ -119,15 +147,6 @@ class _ConnectState extends State<Connect> {
       launch(state.result.login);
       // and start polling the API for login credentials
       _bloc.add(AppPasswordExchangeBlocPoll(state.result.poll));
-    } else if (state is AppPasswordExchangeBlocAppPwSuccess) {
-      final newAccount = Account(
-          Account.newId(),
-          state.result.server.scheme,
-          state.result.server.authority,
-          state.result.loginName.toCi(),
-          state.result.loginName,
-          state.result.appPassword, []);
-      _checkWebDavUrl(context, newAccount);
     } else if (state is AppPasswordExchangeBlocFailure) {
       if (features.isSupportSelfSignedCert &&
           state.exception is HandshakeException) {
@@ -146,6 +165,13 @@ class _ConnectState extends State<Connect> {
         ));
         Navigator.of(context).pop(null);
       }
+    } else if (state is AppPasswordExchangeBlocResult) {
+      if (state.result == null) {
+        // user canceled
+        Navigator.of(context).pop(null);
+      } else {
+        _checkWebDavUrl(context, state.result!);
+      }
     }
   }