wip model: Add TypingNotifier.

Signed-off-by: Zixuan James Li <[email protected]>

Author: PIG208

lib/model/store.dart

@@ -249,6 +249,10 @@ class PerAccountStore extends ChangeNotifier with ChannelStore, MessageStore {
         selfUserId: account.userId,
         typingStartedExpiryPeriod: Duration(milliseconds: initialSnapshot.serverTypingStartedExpiryPeriodMilliseconds),
       ),
+      typingNotifier: TypingNotifier(
+        typingStoppedWaitPeriod: Duration(milliseconds: initialSnapshot.serverTypingStoppedWaitPeriodMilliseconds),
+        typingStartedWaitPeriod: Duration(milliseconds: initialSnapshot.serverTypingStartedWaitPeriodMilliseconds),
+      ),
       channels: channels,
       messages: MessageStoreImpl(),
       unreads: Unreads(
@@ -276,6 +280,7 @@ class PerAccountStore extends ChangeNotifier with ChannelStore, MessageStore {
     required this.userSettings,
     required this.users,
     required this.typingStatus,
+    required this.typingNotifier,
     required ChannelStoreImpl channels,
     required MessageStoreImpl messages,
     required this.unreads,
@@ -342,6 +347,7 @@ class PerAccountStore extends ChangeNotifier with ChannelStore, MessageStore {
   final Map<int, User> users;
 
   final TypingStatus typingStatus;
+  final TypingNotifier typingNotifier;
 
   ////////////////////////////////
   // Streams, topics, and stuff about them.
@@ -410,6 +416,7 @@ class PerAccountStore extends ChangeNotifier with ChannelStore, MessageStore {
     unreads.dispose();
     _messages.dispose();
     typingStatus.dispose();
+    typingNotifier.dispose();
     super.dispose();
   }
 

lib/model/typing_status.dart

@@ -1,10 +1,14 @@
 import 'dart:async';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
 
 import '../api/model/events.dart';
+import '../api/route/messages.dart';
+import '../api/route/typing.dart';
 import '../log.dart';
 import 'narrow.dart';
+import 'store.dart';
 
 /// The model for tracking the typing status organized by narrows.
 ///
@@ -85,3 +89,73 @@ class TypingStatus extends ChangeNotifier {
     }
   }
 }
+
+class TypingNotifier {
+  TypingNotifier({
+    required this.typingStoppedWaitPeriod,
+    required this.typingStartedWaitPeriod,
+  });
+
+  final Duration typingStoppedWaitPeriod;
+  final Duration typingStartedWaitPeriod;
+
+  MessageDestination? _currentDestination;
+  DateTime? _nextStartTime;
+  Timer? _stopTimer;
+
+  void dispose() {
+    _stopTimer?.cancel();
+  }
+
+  void handleTypingStop(PerAccountStore store, MessageDestination destination) {
+    if (destination != _currentDestination) return;
+
+    _notifyStop(store);
+  }
+
+  void handleTyping(PerAccountStore store, MessageDestination destination) {
+    // Two cases.
+    // Renew a previous typing status,
+    // or start a new typing status
+    if (destination == _currentDestination) {
+      _maybeNotifyStart(store);
+      return;
+    }
+
+    _nextStartTime = null;
+    // Start new typing status
+    _currentDestination = destination;
+    _notifyStart(store);
+  }
+
+  Future<void> _maybeNotifyStart(PerAccountStore store) async {
+    if (_nextStartTime == null || DateTime.now().isAfter(_nextStartTime!)) {
+      await _notifyStart(store);
+    }
+  }
+
+  Future<void> _notifyStart(PerAccountStore store) async {
+    _nextStartTime = DateTime.now().add(typingStartedWaitPeriod);
+    _startOrExtendIdleTimer(store);
+    assert(debugLog('[$_currentDestination] notify start'));
+    await setTypingStatus(store.connection,
+      op: TypingOp.start,
+      destination: _currentDestination!,
+    );
+  }
+
+  Future<void> _notifyStop(PerAccountStore store) async {
+    assert(debugLog('[$_currentDestination] notify stop'));
+    _stopTimer?.cancel();
+    await setTypingStatus(store.connection,
+      op: TypingOp.stop,
+      destination: _currentDestination!,
+    );
+    _currentDestination = null;
+  }
+
+  void _startOrExtendIdleTimer(PerAccountStore store) {
+    _stopTimer?.cancel();
+    _stopTimer = Timer(typingStoppedWaitPeriod, () => _notifyStop(store));
+  }
+}