Navigate to conversation on tapping notification

lib/notifications.dart

@@ -1,10 +1,19 @@
+import 'dart:convert';
+
+import 'package:collection/collection.dart';
+import 'package:crypto/crypto.dart';
 import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
 import 'package:flutter_local_notifications/flutter_local_notifications.dart';
 
 import 'api/notifications.dart';
 import 'log.dart';
 import 'model/binding.dart';
+import 'model/narrow.dart';
 import 'widgets/app.dart';
+import 'widgets/message_list.dart';
+import 'widgets/page.dart';
+import 'widgets/store.dart';
 
 class NotificationService {
   static NotificationService get instance => (_instance ??= NotificationService._());
@@ -179,16 +188,17 @@ class NotificationChannelManager {
 
 /// Service for managing the notifications shown to the user.
 class NotificationDisplayManager {
-  // We rely on the tag instead.
-  @visibleForTesting
-  static const kNotificationId = 0;
-
   static Future<void> _init() async {
     await ZulipBinding.instance.notifications.initialize(
       const InitializationSettings(
         android: AndroidInitializationSettings('zulip_notification'),
       ),
+      onDidReceiveNotificationResponse: _onNotificationOpened,
     );
+    final launchDetails = await ZulipBinding.instance.notifications.getNotificationAppLaunchDetails();
+    if (launchDetails?.didNotificationLaunchApp ?? false) {
+      _handleNotificationAppLaunch(launchDetails!.notificationResponse);
+    }
     await NotificationChannelManager._ensureChannel();
   }
 
@@ -204,10 +214,22 @@ class NotificationDisplayManager {
       FcmMessageDmRecipient() =>
         data.senderFullName,
     };
+    final conversationKey = _conversationKey(data);
     ZulipBinding.instance.notifications.show(
-      kNotificationId,
+      // When creating the PendingIntent for the user to open the notification,
+      // the plugin makes the underlying Intent objects look the same.
+      // They differ in their extras, but that doesn't count:
+      //   https://developer.android.com/reference/android/app/PendingIntent
+      //
+      // This leaves only PendingIntent.requestCode to distinguish one
+      // PendingIntent from another; the plugin sets that to the notification ID.
+      // We need a distinct PendingIntent for each conversation, so that the
+      // notifications can lead to the right conversations when opened.
+      // So, use a hash of the conversation key.
+      notificationIdAsHashOf(conversationKey),
       title,
       data.content,
+      payload: jsonEncode(dataJson),
       NotificationDetails(android: AndroidNotificationDetails(
         NotificationChannelManager.kChannelId,
         // This [FlutterLocalNotificationsPlugin.show] call can potentially create
@@ -218,13 +240,31 @@ class NotificationDisplayManager {
         // But really we should fix flutter_local_notifications to not do that
         // (see issue linked below), or replace that package entirely (#351).
         '(Zulip internal error)', // TODO never implicitly create channel: https://github.com/MaikuB/flutter_local_notifications/issues/2135
-        tag: _conversationKey(data),
+        tag: conversationKey,
         color: kZulipBrandColor,
         icon: 'zulip_notification', // TODO vary for debug
         // TODO(#128) inbox-style
+
+        // TODO plugin sets PendingIntent.FLAG_UPDATE_CURRENT; is that OK?
+        // TODO plugin doesn't set our Intent flags; is that OK?
       )));
   }
 
+  /// A notification ID, derived as a hash of the given string key.
+  ///
+  /// The result fits in 31 bits, the size of a nonnegative Java `int`,
+  /// so that it can be used as an Android notification ID.  (It's possible
+  /// negative values would work too, which would add one bit.)
+  ///
+  /// This is a cryptographic hash, meaning that collisions are about as
+  /// unlikely as one could hope for given the size of the hash.
+  @visibleForTesting
+  static int notificationIdAsHashOf(String key) {
+    final bytes = sha256.convert(utf8.encode(key)).bytes;
+    return bytes[0] | (bytes[1] << 8) | (bytes[2] << 16)
+      | ((bytes[3] & 0x7f) << 24);
+  }
+
   static String _conversationKey(MessageFcmMessage data) {
     final groupKey = _groupKey(data);
     final conversation = switch (data.recipient) {
@@ -239,4 +279,46 @@ class NotificationDisplayManager {
     //   https://url.spec.whatwg.org/#url-code-points
     return "${data.realmUri}|${data.userId}";
   }
+
+  static void _onNotificationOpened(NotificationResponse response) async {
+    final data = MessageFcmMessage.fromJson(jsonDecode(response.payload!));
+    assert(debugLog('opened notif: message ${data.zulipMessageId}, content ${data.content}'));
+    _navigateForNotification(data);
+  }
+
+  static void _handleNotificationAppLaunch(NotificationResponse? response) async {
+    assert(response != null);
+    if (response == null) return; // TODO(log) seems like a bug in flutter_local_notifications if this can happen
+
+    final data = MessageFcmMessage.fromJson(jsonDecode(response.payload!));
+    assert(debugLog('launched from notif: message ${data.zulipMessageId}, content ${data.content}'));
+    _navigateForNotification(data);
+  }
+
+  static void _navigateForNotification(MessageFcmMessage data) async {
+    NavigatorState navigator = await ZulipApp.navigator;
+    final context = navigator.context;
+    assert(context.mounted);
+    if (!context.mounted) return; // TODO(linter): this is impossible as there's no actual async gap, but the use_build_context_synchronously lint doesn't see that
+
+    final globalStore = GlobalStoreWidget.of(context);
+    final account = globalStore.accounts.firstWhereOrNull((account) =>
+      account.realmUrl == data.realmUri && account.userId == data.userId);
+    if (account == null) return; // TODO(log)
+
+    final narrow = switch (data.recipient) {
+      FcmMessageStreamRecipient(:var streamId, :var topic) =>
+        TopicNarrow(streamId, topic),
+      FcmMessageDmRecipient(:var allRecipientIds) =>
+        DmNarrow(allRecipientIds: allRecipientIds, selfUserId: account.userId),
+    };
+
+    assert(debugLog('  account: $account, narrow: $narrow'));
+    // TODO(nav): Better interact with existing nav stack on notif open
+    navigator.push(MaterialWidgetRoute(
+      page: PerAccountStoreWidget(accountId: account.id,
+        // TODO(#82): Open at specific message, not just conversation
+        child: MessageListPage(narrow: narrow))));
+    return;
+  }
 }

lib/widgets/app.dart

@@ -1,4 +1,8 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/scheduler.dart';
 import 'package:flutter_gen/gen_l10n/zulip_localizations.dart';
 
 import '../model/localizations.dart';
@@ -11,7 +15,66 @@ import 'recent_dm_conversations.dart';
 import 'store.dart';
 
 class ZulipApp extends StatelessWidget {
-  const ZulipApp({super.key});
+  const ZulipApp({super.key, this.navigatorObservers});
+
+  /// Whether the app's widget tree is ready.
+  ///
+  /// This begins as false.  It transitions to true when the
+  /// [GlobalStore] has been loaded and the [MaterialApp] has been mounted,
+  /// and then remains true.
+  static ValueListenable<bool> get ready => _ready;
+  static ValueNotifier<bool> _ready = ValueNotifier(false);
+
+  /// The navigator for the whole app.
+  ///
+  /// This is always the [GlobalKey.currentState] of [navigatorKey].
+  /// If [navigatorKey] is already mounted, this future completes immediately.
+  /// Otherwise, it waits for [ready] to become true and then completes.
+  static Future<NavigatorState> get navigator {
+    final state = navigatorKey.currentState;
+    if (state != null) return Future.value(state);
+
+    assert(!ready.value);
+    final completer = Completer<NavigatorState>();
+    ready.addListener(() {
+      assert(ready.value);
+      completer.complete(navigatorKey.currentState!);
+    });
+    return completer.future;
+  }
+
+  /// A key for the navigator for the whole app.
+  ///
+  /// For code that exists entirely outside the widget tree and has no natural
+  /// [BuildContext] of its own, this enables interacting with the app's
+  /// navigation, by calling [GlobalKey.currentState] to get a [NavigatorState].
+  ///
+  /// During the app's early startup, this key will not yet be mounted.
+  /// It will always be mounted before [ready] becomes true,
+  /// and naturally before any widgets are mounted which are part of the
+  /// app's main UI managed by the navigator.
+  ///
+  /// See also [navigator], to asynchronously wait for the navigator
+  /// to be mounted.
+  static final navigatorKey = GlobalKey<NavigatorState>();
+
+  /// Reset the state of [ZulipApp] statics, for testing.
+  ///
+  /// TODO refactor this better, perhaps unify with ZulipBinding
+  @visibleForTesting
+  static void debugReset() {
+    _ready.dispose();
+    _ready = ValueNotifier(false);
+  }
+
+  /// A list to pass through to [MaterialApp.navigatorObservers].
+  /// Useful in tests.
+  final List<NavigatorObserver>? navigatorObservers;
+
+  void _declareReady() {
+    assert(navigatorKey.currentContext != null);
+    _ready.value = true;
+  }
 
   @override
   Widget build(BuildContext context) {
@@ -50,7 +113,13 @@ class ZulipApp extends StatelessWidget {
         localizationsDelegates: ZulipLocalizations.localizationsDelegates,
         supportedLocales: ZulipLocalizations.supportedLocales,
         theme: theme,
+        navigatorKey: navigatorKey,
+        navigatorObservers: navigatorObservers ?? const [],
         builder: (BuildContext context, Widget? child) {
+          if (!ready.value) {
+            SchedulerBinding.instance.addPostFrameCallback(
+              (_) => _declareReady());
+          }
           GlobalLocalizations.zulipLocalizations = ZulipLocalizations.of(context);
           return child!;
         },

pubspec.lock

@@ -218,7 +218,7 @@ packages:
     source: hosted
     version: "0.3.3+6"
   crypto:
-    dependency: transitive
+    dependency: "direct main"
     description:
       name: crypto
       sha256: ff625774173754681d66daaf4a448684fb04b78f902da9cb3d308c19cc5e8bab

pubspec.yaml

@@ -64,6 +64,7 @@ dependencies:
   firebase_core: ^2.14.0
   flutter_local_notifications_platform_interface: ^7.0.0+1
   flutter_local_notifications: ^16.1.0
+  crypto: ^3.0.3
 
 dev_dependencies:
   flutter_driver:

test/example_data.dart

@@ -14,6 +14,7 @@ import 'stdlib_checks.dart';
 //
 
 final Uri realmUrl = Uri.parse('https://chat.example/');
+Uri get _realmUrl => realmUrl;
 
 const String recentZulipVersion = '8.0';
 const int recentZulipFeatureLevel = 185;
@@ -53,28 +54,36 @@ User user({
   );
 }
 
+Account account({
+  int? id,
+  Uri? realmUrl,
+  required User user,
+  String? apiKey,
+}) {
+  return Account(
+    id: id ?? 1000, // TODO generate example IDs
+    realmUrl: realmUrl ?? _realmUrl,
+    email: user.email,
+    apiKey: apiKey ?? 'aeouasdf',
+    userId: user.userId,
+    zulipFeatureLevel: recentZulipFeatureLevel,
+    zulipVersion: recentZulipVersion,
+    zulipMergeBase: recentZulipVersion,
+  );
+}
+
 final User selfUser = user(fullName: 'Self User', email: 'self@example', userId: 123);
-final Account selfAccount = Account(
+final Account selfAccount = account(
   id: 1001,
-  realmUrl: realmUrl,
-  email: selfUser.email,
+  user: selfUser,
   apiKey: 'asdfqwer',
-  userId: selfUser.userId,
-  zulipFeatureLevel: recentZulipFeatureLevel,
-  zulipVersion: recentZulipVersion,
-  zulipMergeBase: recentZulipVersion,
 );
 
 final User otherUser = user(fullName: 'Other User', email: 'other@example', userId: 234);
-final Account otherAccount = Account(
+final Account otherAccount = account(
   id: 1002,
-  realmUrl: realmUrl,
-  email: otherUser.email,
+  user: otherUser,
   apiKey: 'sdfgwert',
-  userId: otherUser.userId,
-  zulipFeatureLevel: recentZulipFeatureLevel,
-  zulipVersion: recentZulipVersion,
-  zulipMergeBase: recentZulipVersion,
 );
 
 final User thirdUser = user(fullName: 'Third User', email: 'third@example', userId: 345);

test/model/binding.dart

@@ -8,6 +8,7 @@ import 'package:test/fake.dart';
 import 'package:url_launcher/url_launcher.dart' as url_launcher;
 import 'package:zulip/model/binding.dart';
 import 'package:zulip/model/store.dart';
+import 'package:zulip/widgets/app.dart';
 
 import 'test_store.dart';
 
@@ -61,6 +62,7 @@ class TestZulipBinding extends ZulipBinding {
   /// should clean up by calling this method.  Typically this is done using
   /// [addTearDown], like `addTearDown(testBinding.reset);`.
   void reset() {
+    ZulipApp.debugReset();
     _resetStore();
     _resetLaunchUrl();
     _resetDeviceInfo();
@@ -317,6 +319,20 @@ class FakeFlutterLocalNotificationsPlugin extends Fake implements FlutterLocalNo
     assert(initializationSettings != null);
     _showCalls.add((id, title, body, notificationDetails, payload: payload));
   }
+
+  /// The value to be returned by [getNotificationAppLaunchDetails].
+  NotificationAppLaunchDetails? appLaunchDetails;
+
+  @override
+  Future<NotificationAppLaunchDetails?> getNotificationAppLaunchDetails() {
+    return Future.value(appLaunchDetails);
+  }
+
+  void receiveNotificationResponse(NotificationResponse details) {
+    if (onDidReceiveNotificationResponse != null) {
+      onDidReceiveNotificationResponse!(details);
+    }
+  }
 }
 
 typedef FlutterLocalNotificationsPluginShowCall = (