model: Add data models for typing events.

lib/api/model/events.dart

@@ -62,6 +62,7 @@ sealed class Event {
           case 'remove': return UpdateMessageFlagsRemoveEvent.fromJson(json);
           default: return UnexpectedEvent.fromJson(json);
         }
+      case 'typing': return TypingEvent.fromJson(json);
       case 'reaction': return ReactionEvent.fromJson(json);
       case 'heartbeat': return HeartbeatEvent.fromJson(json);
       // TODO add many more event types
@@ -707,6 +708,9 @@ class DeleteMessageEvent extends Event {
 
   final List<int> messageIds;
   // final int messageId; // Not present; we support the bulk_message_deletion capability
+  // The server never actually sends "direct" here yet (it's "private" instead),
+  // but we accept both forms for forward-compatibility.
+  @MessageTypeConverter()
   final MessageType messageType;
   final int? streamId;
   final String? topic;
@@ -733,12 +737,28 @@ class DeleteMessageEvent extends Event {
   Map<String, dynamic> toJson() => _$DeleteMessageEventToJson(this);
 }
 
-/// As in [DeleteMessageEvent.messageType]
-/// or [UpdateMessageFlagsMessageDetail.type].
-@JsonEnum(fieldRename: FieldRename.snake)
+/// As in [DeleteMessageEvent.messageType],
+/// [UpdateMessageFlagsMessageDetail.type],
+/// or [TypingEvent.messageType].
+@JsonEnum(alwaysCreate: true)
 enum MessageType {
   stream,
-  private;
+  direct;
+}
+
+class MessageTypeConverter extends JsonConverter<MessageType, String> {
+  const MessageTypeConverter();
+
+  @override
+  MessageType fromJson(String json) {
+    if (json == 'private') json = 'direct'; // TODO(server-future)
+    return $enumDecode(_$MessageTypeEnumMap, json);
+  }
+
+  @override
+  String toJson(MessageType object) {
+    return _$MessageTypeEnumMap[object]!;
+  }
 }
 
 /// A Zulip event of type `update_message_flags`.
@@ -820,6 +840,9 @@ class UpdateMessageFlagsRemoveEvent extends UpdateMessageFlagsEvent {
 /// As in [UpdateMessageFlagsRemoveEvent.messageDetails].
 @JsonSerializable(fieldRename: FieldRename.snake)
 class UpdateMessageFlagsMessageDetail {
+  // The server never actually sends "direct" here yet (it's "private" instead),
+  // but we accept both forms for forward-compatibility.
+  @MessageTypeConverter()
   final MessageType type;
   final bool? mentioned;
   final List<int>? userIds;
@@ -841,7 +864,7 @@ class UpdateMessageFlagsMessageDetail {
       case MessageType.stream:
         result.streamId as int;
         result.topic as String;
-      case MessageType.private:
+      case MessageType.direct:
         result.userIds as List<int>;
     }
     return result;
@@ -850,6 +873,69 @@ class UpdateMessageFlagsMessageDetail {
   Map<String, dynamic> toJson() => _$UpdateMessageFlagsMessageDetailToJson(this);
 }
 
+/// A Zulip event of type `typing`:
+///   https://zulip.com/api/get-events#typing-start
+///   https://zulip.com/api/get-events#typing-stop
+@JsonSerializable(fieldRename: FieldRename.snake)
+class TypingEvent extends Event {
+  @override
+  @JsonKey(includeToJson: true)
+  String get type => 'typing';
+
+  final TypingOp op;
+  @MessageTypeConverter()
+  final MessageType messageType;
+  @JsonKey(readValue: _readSenderId)
+  final int senderId;
+  @JsonKey(name: 'recipients', fromJson: _recipientIdsFromJson)
+  final List<int>? recipientIds;
+  final int? streamId;
+  final String? topic;
+
+  TypingEvent({
+    required super.id,
+    required this.op,
+    required this.messageType,
+    required this.senderId,
+    required this.recipientIds,
+    required this.streamId,
+    required this.topic,
+  });
+
+  static Object? _readSenderId(Map<Object?, Object?> json, String key) {
+    return (json['sender'] as Map<String, dynamic>)['user_id'];
+  }
+
+  static List<int>? _recipientIdsFromJson(Object? json) {
+    if (json == null) return null;
+    return (json as List<Object?>).map(
+      (item) => (item as Map<String, Object?>)['user_id'] as int).toList();
+  }
+
+  factory TypingEvent.fromJson(Map<String, dynamic> json) {
+    final result = _$TypingEventFromJson(json);
+    // Crunchy-shell validation
+    switch (result.messageType) {
+      case MessageType.stream:
+        result.streamId as int;
+        result.topic as String;
+      case MessageType.direct:
+        result.recipientIds as List<int>;
+    }
+    return result;
+  }
+
+  @override
+  Map<String, dynamic> toJson() => _$TypingEventToJson(this);
+}
+
+/// As in [TypingEvent.op].
+@JsonEnum(fieldRename: FieldRename.snake)
+enum TypingOp {
+  start,
+  stop
+}
+
 /// A Zulip event of type `reaction`, with op `add` or `remove`.
 ///
 /// See:

lib/api/model/initial_snapshot.dart

@@ -24,6 +24,14 @@ class InitialSnapshot {
 
   final List<CustomProfileField> customProfileFields;
 
+  // TODO(server-8): Remove the default values.
+  @JsonKey(defaultValue: 15000)
+  final int serverTypingStartedExpiryPeriodMilliseconds;
+  @JsonKey(defaultValue: 5000)
+  final int serverTypingStoppedWaitPeriodMilliseconds;
+  @JsonKey(defaultValue: 10000)
+  final int serverTypingStartedWaitPeriodMilliseconds;
+
   // final List<…> mutedTopics; // TODO(#422) we ignore this feature on older servers
 
   final Map<String, RealmEmojiItem> realmEmoji;
@@ -86,6 +94,9 @@ class InitialSnapshot {
     required this.zulipMergeBase,
     required this.alertWords,
     required this.customProfileFields,
+    required this.serverTypingStartedExpiryPeriodMilliseconds,
+    required this.serverTypingStoppedWaitPeriodMilliseconds,
+    required this.serverTypingStartedWaitPeriodMilliseconds,
     required this.realmEmoji,
     required this.recentPrivateConversations,
     required this.subscriptions,

lib/model/narrow.dart

@@ -204,7 +204,7 @@ class DmNarrow extends Narrow implements SendableNarrow {
     UpdateMessageFlagsMessageDetail detail, {
     required int selfUserId,
   }) {
-    assert(detail.type == MessageType.private);
+    assert(detail.type == MessageType.direct);
     return DmNarrow.withOtherUsers(detail.userIds!, selfUserId: selfUserId);
   }
 

lib/model/store.dart

@@ -24,6 +24,7 @@ import 'message.dart';
 import 'message_list.dart';
 import 'recent_dm_conversations.dart';
 import 'stream.dart';
+import 'typing_status.dart';
 import 'unreads.dart';
 
 export 'package:drift/drift.dart' show Value;
@@ -242,6 +243,10 @@ class PerAccountStore extends ChangeNotifier with StreamStore, MessageStore {
         .followedBy(initialSnapshot.realmNonActiveUsers)
         .followedBy(initialSnapshot.crossRealmBots)
         .map((user) => MapEntry(user.userId, user))),
+      typingStatus: TypingStatus(
+        selfUserId: account.userId,
+        typingStartedExpiryPeriod: Duration(milliseconds: initialSnapshot.serverTypingStartedExpiryPeriodMilliseconds),
+      ),
       streams: streams,
       messages: MessageStoreImpl(),
       unreads: Unreads(
@@ -266,6 +271,7 @@ class PerAccountStore extends ChangeNotifier with StreamStore, MessageStore {
     required this.selfUserId,
     required this.userSettings,
     required this.users,
+    required this.typingStatus,
     required StreamStoreImpl streams,
     required MessageStoreImpl messages,
     required this.unreads,
@@ -319,6 +325,8 @@ class PerAccountStore extends ChangeNotifier with StreamStore, MessageStore {
 
   final Map<int, User> users;
 
+  final TypingStatus typingStatus;
+
   ////////////////////////////////
   // Streams, topics, and stuff about them.
 
@@ -383,6 +391,7 @@ class PerAccountStore extends ChangeNotifier with StreamStore, MessageStore {
     recentDmConversationsView.dispose();
     unreads.dispose();
     _messages.dispose();
+    typingStatus.dispose();
     super.dispose();
   }
 
@@ -485,6 +494,9 @@ class PerAccountStore extends ChangeNotifier with StreamStore, MessageStore {
       assert(debugLog("server event: update_message_flags/${event.op} ${event.flag.toJson()}"));
       _messages.handleUpdateMessageFlagsEvent(event);
       unreads.handleUpdateMessageFlagsEvent(event);
+    } else if (event is TypingEvent) {
+      assert(debugLog("server event: typing/${event.op} ${event.messageType}"));
+      typingStatus.handleTypingEvent(event);
     } else if (event is ReactionEvent) {
       assert(debugLog("server event: reaction/${event.op}"));
       _messages.handleReactionEvent(event);