Confirm before unsubscribing (always, if from action sheet; only sometimes, if from "All channels")

assets/l10n/app_en.arb

@@ -140,7 +140,7 @@
   "@unsubscribeConfirmationDialogTitle": {
     "description": "Title for a confirmation dialog for unsubscribing from a channel.",
     "placeholders": {
-      "channelName": {"type": "String", "example": "mobile"}
+      "channelName": {"type": "String", "example": "#mobile"}
     }
   },
   "unsubscribeConfirmationDialogMessageCannotResubscribe": "Once you leave this channel, you will not be able to rejoin.",

lib/widgets/action_sheet.dart

@@ -17,7 +17,6 @@ import '../model/content.dart';
 import '../model/emoji.dart';
 import '../model/internal_link.dart';
 import '../model/narrow.dart';
-import '../model/realm.dart';
 import 'actions.dart';
 import 'button.dart';
 import 'color.dart';
@@ -634,45 +633,7 @@ class UnsubscribeButton extends ActionSheetMenuItemButton {
 
   @override
   void onPressed() async {
-    final store = PerAccountStoreWidget.of(pageContext);
-    final subscription = store.subscriptions[channelId];
-    if (subscription == null) return; // TODO could give feedback
-
-    // TODO(future) check if the self-user is a guest and the channel is not web-public
-    final couldResubscribe = !subscription.inviteOnly
-      || store.selfHasPermissionForGroupSetting(subscription.canSubscribeGroup,
-           GroupSettingType.stream, 'can_subscribe_group');
-    if (!couldResubscribe) {
-      // TODO(#1788) warn if org would lose content access (nobody can subscribe)
-      final zulipLocalizations = ZulipLocalizations.of(pageContext);
-
-      final dialog = showSuggestedActionDialog(context: pageContext,
-        title: zulipLocalizations.unsubscribeConfirmationDialogTitle(subscription.name),
-        message: zulipLocalizations.unsubscribeConfirmationDialogMessageCannotResubscribe,
-        destructiveActionButton: true,
-        actionButtonText: zulipLocalizations.unsubscribeConfirmationDialogConfirmButton);
-      if (await dialog.result != true) return;
-      if (!pageContext.mounted) return;
-    }
-
-    try {
-      await unsubscribeFromChannel(PerAccountStoreWidget.of(pageContext).connection,
-        subscriptions: [subscription.name]);
-    } catch (e) {
-      if (!pageContext.mounted) return;
-
-      String? errorMessage;
-      switch (e) {
-        case ZulipApiException():
-          errorMessage = e.message;
-          // TODO(#741) specific messages for common errors, like network errors
-          //   (support with reusable code)
-        default:
-      }
-
-      final title = ZulipLocalizations.of(pageContext).unsubscribeFailedTitle;
-      showErrorDialog(context: pageContext, title: title, message: errorMessage);
-    }
+    await ZulipAction.unsubscribeFromChannel(pageContext, channelId: channelId);
   }
 }
 

lib/widgets/actions.dart

@@ -7,9 +7,11 @@ import '../api/exception.dart';
 import '../api/model/model.dart';
 import '../api/model/narrow.dart';
 import '../api/route/messages.dart';
+import '../api/route/channels.dart' as channels_api;
 import '../generated/l10n/zulip_localizations.dart';
 import '../model/binding.dart';
 import '../model/narrow.dart';
+import '../model/realm.dart';
 import 'dialog.dart';
 import 'store.dart';
 
@@ -239,6 +241,64 @@ abstract final class ZulipAction {
 
     return fetchedMessage?.content;
   }
+
+  /// Unsubscribe from a channel, possibly after a confirmation dialog,
+  /// showing an error dialog on failure.
+  ///
+  /// A confirmation dialog is shown if the user would not have permission
+  /// to resubscribe.
+  /// If [alwaysAsk] is true (the default),
+  /// a confirmation dialog is shown unconditionally.
+  static Future<void> unsubscribeFromChannel(BuildContext context, {
+    required int channelId,
+    bool alwaysAsk = true,
+  }) async {
+    final store = PerAccountStoreWidget.of(context);
+    final subscription = store.subscriptions[channelId];
+    if (subscription == null) return; // TODO could give feedback
+
+    // TODO(future) check if the self-user is a guest and the channel is not web-public
+    final couldResubscribe = !subscription.inviteOnly
+      || store.selfHasPermissionForGroupSetting(subscription.canSubscribeGroup,
+           GroupSettingType.stream, 'can_subscribe_group');
+    final zulipLocalizations = ZulipLocalizations.of(context);
+    if (!couldResubscribe) {
+      // TODO(#1788) warn if org would lose content access (nobody can subscribe)
+
+      final dialog = showSuggestedActionDialog(context: context,
+        title: zulipLocalizations.unsubscribeConfirmationDialogTitle('#${subscription.name}'),
+        message: zulipLocalizations.unsubscribeConfirmationDialogMessageCannotResubscribe,
+        destructiveActionButton: true,
+        actionButtonText: zulipLocalizations.unsubscribeConfirmationDialogConfirmButton);
+      if (await dialog.result != true) return;
+      if (!context.mounted) return;
+    } else if (alwaysAsk) {
+      final dialog = showSuggestedActionDialog(context: context,
+        title: zulipLocalizations.unsubscribeConfirmationDialogTitle('#${subscription.name}'),
+        actionButtonText: zulipLocalizations.unsubscribeConfirmationDialogConfirmButton);
+      if (await dialog.result != true) return;
+      if (!context.mounted) return;
+    }
+
+    try {
+      await channels_api.unsubscribeFromChannel(PerAccountStoreWidget.of(context).connection,
+        subscriptions: [subscription.name]);
+    } catch (e) {
+      if (!context.mounted) return;
+
+      String? errorMessage;
+      switch (e) {
+        case ZulipApiException():
+          errorMessage = e.message;
+          // TODO(#741) specific messages for common errors, like network errors
+          //   (support with reusable code)
+        default:
+      }
+
+      final title = ZulipLocalizations.of(context).unsubscribeFailedTitle;
+      showErrorDialog(context: context, title: title, message: errorMessage);
+    }
+  }
 }
 
 /// Methods that act through platform APIs and show feedback in the UI.

lib/widgets/all_channels.dart

@@ -6,6 +6,7 @@ import '../generated/l10n/zulip_localizations.dart';
 import '../log.dart';
 import '../model/channel.dart';
 import 'action_sheet.dart';
+import 'actions.dart';
 import 'app_bar.dart';
 import 'button.dart';
 import 'icons.dart';
@@ -137,8 +138,9 @@ class _SubscribeToggle extends StatelessWidget {
           await subscribeToChannel(store.connection,
             subscriptions: [channel.name]);
         } else {
-          await unsubscribeFromChannel(store.connection,
-            subscriptions: [channel.name]);
+          await ZulipAction.unsubscribeFromChannel(context,
+            channelId: channel.streamId,
+            alwaysAsk: false);
         }
       },
       // TODO(#741) interpret API errors for user

lib/widgets/dialog.dart

@@ -145,7 +145,7 @@ DialogStatus<void> showErrorDialog({
 DialogStatus<bool> showSuggestedActionDialog({
   required BuildContext context,
   required String title,
-  required String message,
+  String? message,
   required String? actionButtonText,
   bool destructiveActionButton = false,
 }) {
@@ -154,7 +154,7 @@ DialogStatus<bool> showSuggestedActionDialog({
     context: context,
     builder: (BuildContext context) => AlertDialog.adaptive(
       title: Text(title),
-      content: _adaptiveContent(Text(message)),
+      content: message != null ? _adaptiveContent(Text(message)) : null,
       actions: [
         _adaptiveAction(
           onPressed: () => Navigator.pop<bool>(context, null),

test/widgets/action_sheet_test.dart

@@ -573,9 +573,15 @@ void main() {
 
         connection.prepare(json: {});
         await tapButton(tester);
-        await tester.pump(Duration.zero);
+        await tester.pump();
 
-        checkNoDialog(tester);
+        final (unsubscribeButton, cancelButton) = checkSuggestedActionDialog(tester,
+          expectedTitle: 'Unsubscribe from #${channel.name}?',
+          expectDestructiveActionButton: false,
+          expectedActionButtonText: 'Unsubscribe');
+        await tester.tap(find.byWidget(unsubscribeButton));
+        await tester.pump();
+        await tester.pump(Duration.zero);
 
         check(connection.lastRequest).isA<http.Request>()
           ..method.equals('DELETE')
@@ -599,7 +605,7 @@ void main() {
         await tester.pump();
 
         final (unsubscribeButton, cancelButton) = checkSuggestedActionDialog(tester,
-          expectedTitle: 'Unsubscribe from ${channel.name}?',
+          expectedTitle: 'Unsubscribe from #${channel.name}?',
           expectedMessage: 'Once you leave this channel, you will not be able to rejoin.',
           expectDestructiveActionButton: true,
           expectedActionButtonText: 'Unsubscribe');

test/widgets/all_channels_test.dart

@@ -1,7 +1,10 @@
+import 'dart:convert';
+
 import 'package:checks/checks.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_checks/flutter_checks.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart' as http;
 import 'package:zulip/api/model/model.dart';
 import 'package:zulip/model/store.dart';
 import 'package:zulip/widgets/all_channels.dart';
@@ -10,20 +13,25 @@ import 'package:zulip/widgets/button.dart';
 import 'package:zulip/widgets/home.dart';
 import 'package:zulip/widgets/icons.dart';
 import 'package:zulip/widgets/page.dart';
+import 'package:zulip/widgets/remote_settings.dart';
 import 'package:zulip/widgets/theme.dart';
 
+import '../api/fake_api.dart';
 import '../api/model/model_checks.dart';
 import '../flutter_checks.dart';
 import '../model/binding.dart';
 import '../example_data.dart' as eg;
 import '../model/test_store.dart';
+import '../stdlib_checks.dart';
 import 'checks.dart';
+import 'dialog_checks.dart';
 import 'test_app.dart';
 
 void main() {
   TestZulipBinding.ensureInitialized();
 
   late PerAccountStore store;
+  late FakeApiConnection connection;
   late TransitionDurationObserver transitionDurationObserver;
 
   final groupSettingWithSelf = eg.groupSetting(members: [eg.selfUser.userId]);
@@ -40,6 +48,7 @@ void main() {
     );
     await testBinding.globalStore.add(eg.selfAccount, initialSnapshot);
     store = await testBinding.globalStore.perAccount(eg.selfAccount.id);
+    connection = store.connection as FakeApiConnection;
 
     transitionDurationObserver = TransitionDurationObserver();
     await tester.pumpWidget(TestZulipApp(accountId: eg.selfAccount.id,
@@ -207,4 +216,79 @@ void main() {
 
     check(find.byType(BottomSheet)).findsOne();
   });
+
+  testWidgets('use toggle switch to subscribe/unsubscribe', (tester) async {
+    final channel = eg.stream();
+    await setupAllChannelsPage(tester, channels: [channel]);
+
+    await tester.tap(find.byType(Toggle));
+    check(connection.lastRequest).isA<http.Request>()
+      ..method.equals('POST')
+      ..url.path.equals('/api/v1/users/me/subscriptions')
+      ..bodyFields.deepEquals({
+        'subscriptions': jsonEncode([{'name': channel.name}]),
+      });
+
+    await store.addSubscription(eg.subscription(channel));
+    await tester.pump(); // Toggle changes state
+
+    await tester.tap(find.byType(Toggle));
+    check(connection.lastRequest).isA<http.Request>()
+      ..method.equals('DELETE')
+      ..url.path.equals('/api/v1/users/me/subscriptions')
+      ..bodyFields.deepEquals({
+        'subscriptions': jsonEncode([channel.name]),
+      });
+  });
+
+  testWidgets('Toggle "off" to unsubscribe, public channel', (tester) async {
+    final channel = eg.stream(inviteOnly: false);
+    final subscription = eg.subscription(channel);
+
+    await setupAllChannelsPage(tester, channels: [subscription]);
+
+    connection.prepare(json: {});
+    await tester.tap(find.byType(Toggle));
+    await tester.pump(Duration.zero);
+    checkNoDialog(tester);
+    check(connection.lastRequest).isA<http.Request>()
+      ..method.equals('DELETE')
+      ..url.path.equals('/api/v1/users/me/subscriptions')
+      ..bodyFields.deepEquals({
+        'subscriptions': jsonEncode([channel.name]),
+      });
+  });
+
+  testWidgets('Toggle "off" to unsubscribe, but without resubscribe permission', (tester) async {
+    final channel = eg.stream(
+      inviteOnly: true, canSubscribeGroup: eg.groupSetting(members: []));
+    final subscription = eg.subscription(channel);
+
+    (Widget, Widget) checkConfirmDialog() => checkSuggestedActionDialog(tester,
+      expectedTitle: 'Unsubscribe from #${channel.name}?',
+      expectedMessage: 'Once you leave this channel, you will not be able to rejoin.',
+      expectDestructiveActionButton: true,
+      expectedActionButtonText: 'Unsubscribe');
+
+    await setupAllChannelsPage(tester, channels: [subscription]);
+
+    await tester.tap(find.byType(Toggle));
+    await tester.pump();
+    final (_, cancelButton) = checkConfirmDialog();
+    await tester.tap(find.byWidget(cancelButton));
+    await tester.pumpAndSettle();
+    check(connection.lastRequest).isNull();
+    await tester.pump(RemoteSettingBuilder.localEchoIdleTimeout);
+
+    await tester.tap(find.byType(Toggle));
+    await tester.pump();
+    final (unsubscribeButton, _) = checkConfirmDialog();
+    await tester.tap(find.byWidget(unsubscribeButton));
+    check(connection.lastRequest).isA<http.Request>()
+      ..method.equals('DELETE')
+      ..url.path.equals('/api/v1/users/me/subscriptions')
+      ..bodyFields.deepEquals({
+        'subscriptions': jsonEncode([channel.name]),
+      });
+  });
 }

test/widgets/dialog_checks.dart

@@ -109,7 +109,7 @@ void checkNoDialog(WidgetTester tester) {
 /// Tap the action button by calling `tester.tap(find.byWidget(actionButton))`.
 (Widget, Widget) checkSuggestedActionDialog(WidgetTester tester, {
   required String expectedTitle,
-  required String expectedMessage,
+  String? expectedMessage,
   String? expectedActionButtonText,
   bool expectDestructiveActionButton = false,
 }) {
@@ -121,8 +121,10 @@ void checkNoDialog(WidgetTester tester) {
       final dialog = tester.widget<AlertDialog>(find.bySubtype<AlertDialog>());
       tester.widget(find.descendant(matchRoot: true,
         of: find.byWidget(dialog.title!), matching: find.text(expectedTitle)));
-      tester.widget(find.descendant(matchRoot: true,
-        of: find.byWidget(dialog.content!), matching: find.text(expectedMessage)));
+      if (expectedMessage != null) {
+        tester.widget(find.descendant(matchRoot: true,
+          of: find.byWidget(dialog.content!), matching: find.text(expectedMessage)));
+      }
 
       final actionButton = tester.widget(find.descendant(of: find.byWidget(dialog),
         matching: find.widgetWithText(TextButton, expectedActionButtonText ?? 'Continue')));
@@ -135,8 +137,10 @@ void checkNoDialog(WidgetTester tester) {
       final dialog = tester.widget<CupertinoAlertDialog>(find.byType(CupertinoAlertDialog));
       tester.widget(find.descendant(matchRoot: true,
         of: find.byWidget(dialog.title!), matching: find.text(expectedTitle)));
-      tester.widget(find.descendant(matchRoot: true,
-        of: find.byWidget(dialog.content!), matching: find.text(expectedMessage)));
+      if (expectedMessage != null) {
+        tester.widget(find.descendant(matchRoot: true,
+          of: find.byWidget(dialog.content!), matching: find.text(expectedMessage)));
+      }
 
       final actionButton = tester.widget<CupertinoDialogAction>(
         find.descendant(