api: Add reaction events

We don't yet have UI to show the events (#121), but now at least
we're keeping our Message objects up-to-date with reactions.

Related: #121

Author: chrisbobbe

lib/api/model/events.dart

@@ -33,6 +33,7 @@ sealed class Event {
       case 'message': return MessageEvent.fromJson(json);
       case 'update_message': return UpdateMessageEvent.fromJson(json);
       case 'delete_message': return DeleteMessageEvent.fromJson(json);
+      case 'reaction': return ReactionEvent.fromJson(json);
       case 'heartbeat': return HeartbeatEvent.fromJson(json);
       // TODO add many more event types
       default: return UnexpectedEvent.fromJson(json);
@@ -370,6 +371,50 @@ enum MessageType {
   private;
 }
 
+/// A Zulip event of type `reaction`, with op `add` or `remove`.
+///
+/// See:
+///   https://zulip.com/api/get-events#reaction-add
+///   https://zulip.com/api/get-events#reaction-remove
+@JsonSerializable(fieldRename: FieldRename.snake)
+class ReactionEvent extends Event {
+  @override
+  @JsonKey(includeToJson: true)
+  String get type => 'reaction';
+
+  final ReactionOp op;
+
+  final String emojiName;
+  final String emojiCode;
+  final ReactionType reactionType;
+  final int userId;
+  // final Map<String, dynamic> user; // deprecated; ignore
+  final int messageId;
+
+  ReactionEvent({
+    required super.id,
+    required this.op,
+    required this.emojiName,
+    required this.emojiCode,
+    required this.reactionType,
+    required this.userId,
+    required this.messageId,
+  });
+
+  factory ReactionEvent.fromJson(Map<String, dynamic> json) =>
+    _$ReactionEventFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$ReactionEventToJson(this);
+}
+
+/// The type of [ReactionEvent.op].
+@JsonEnum(fieldRename: FieldRename.snake)
+enum ReactionOp {
+  add,
+  remove,
+}
+
 /// A Zulip event of type `heartbeat`: https://zulip.com/api/get-events#heartbeat
 @JsonSerializable(fieldRename: FieldRename.snake)
 class HeartbeatEvent extends Event {

lib/api/model/events.g.dart

@@ -464,6 +464,21 @@ class Reaction {
     _$ReactionFromJson(json);
 
   Map<String, dynamic> toJson() => _$ReactionToJson(this);
+
+  @override
+  String toString() => 'Reaction(emojiName: $emojiName, emojiCode: $emojiCode, reactionType: $reactionType, userId: $userId)';
+
+  @override
+  bool operator ==(Object other) {
+    if (other is! Reaction) return false;
+    return other.emojiName  == emojiName
+      && other.emojiCode    == emojiCode
+      && other.reactionType == reactionType
+      && other.userId       == userId;
+  }
+
+  @override
+  int get hashCode => Object.hash('Reaction', emojiName, emojiCode, reactionType, userId);
 }
 
 /// As in [Reaction.reactionType].

lib/api/model/model.dart

@@ -151,6 +151,29 @@ class MessageListView extends ChangeNotifier {
     notifyListeners();
   }
 
+  void maybeUpdateMessageReactions(ReactionEvent event) {
+    final index = findMessageWithId(event.messageId);
+    if (index == -1) {
+      return;
+    }
+
+    final message = messages[index];
+    final reaction = Reaction(
+      emojiName: event.emojiName,
+      emojiCode: event.emojiCode,
+      reactionType: event.reactionType,
+      userId: event.userId,
+    );
+    switch (event.op) {
+      case ReactionOp.add:
+        message.reactions.add(reaction);
+      case ReactionOp.remove:
+        message.reactions.removeWhere((r) => r == reaction);
+    }
+
+    notifyListeners();
+  }
+
   /// Called when the app is reassembled during debugging, e.g. for hot reload.
   ///
   /// This will redo from scratch any computations we can, such as parsing

lib/model/message_list.dart

@@ -278,6 +278,11 @@ class PerAccountStore extends ChangeNotifier {
     } else if (event is DeleteMessageEvent) {
       assert(debugLog("server event: delete_message ${event.messageIds}"));
       // TODO handle
+    } else if (event is ReactionEvent) {
+      assert(debugLog("server event: reaction/${event.op}"));
+      for (final view in _messageListViews) {
+        view.maybeUpdateMessageReactions(event);
+      }
     } else if (event is UnexpectedEvent) {
       assert(debugLog("server event: ${jsonEncode(event.toJson())}")); // TODO log better
     } else {

lib/model/store.dart

@@ -11,6 +11,7 @@ extension MessageChecks on Subject<Message> {
   Subject<String> get content => has((e) => e.content, 'content');
   Subject<bool> get isMeMessage => has((e) => e.isMeMessage, 'isMeMessage');
   Subject<int?> get lastEditTimestamp => has((e) => e.lastEditTimestamp, 'lastEditTimestamp');
+  Subject<List<Reaction>> get reactions => has((e) => e.reactions, 'reactions');
   Subject<List<String>> get flags => has((e) => e.flags, 'flags');
 
   // TODO accessors for other fields

test/api/model/model_checks.dart

@@ -132,6 +132,7 @@ StreamMessage streamMessage({
   String? topic,
   String? content,
   String? contentMarkdown,
+  List<Reaction>? reactions,
   List<String>? flags,
 }) {
   final effectiveStream = stream ?? _stream();
@@ -146,7 +147,7 @@ StreamMessage streamMessage({
     ..._messagePropertiesFromContent(content, contentMarkdown),
     'display_recipient': effectiveStream.name,
     'stream_id': effectiveStream.streamId,
-    'reactions': [],
+    'reactions': reactions?.map((r) => r.toJson()).toList() ?? [],
     'flags': flags ?? [],
     'id': id ?? 1234567, // TODO generate example IDs
     'subject': topic ?? 'example topic',
@@ -184,6 +185,13 @@ DmMessage dmMessage({
   });
 }
 
+Reaction unicodeEmojiReaction = Reaction(
+  emojiName: 'thumbs_up',
+  emojiCode: '1f44d',
+  reactionType: ReactionType.unicodeEmoji,
+  userId: selfUser.userId,
+);
+
 // TODO example data for many more types
 
 InitialSnapshot initialSnapshot({

test/example_data.dart

@@ -221,5 +221,134 @@ void main() async {
         ..content.equals(newContent)
         ..lastEditTimestamp.equals(oldTimestamp);
     });
+
+    group('ReactionEvent handling', () {
+      test('add reaction', () async {
+        final store = await setupStore(stream);
+        final originalMessage = eg.streamMessage(id: 243, stream: stream, reactions: []);
+        final messageList = await messageListViewWithMessages([originalMessage], store, narrow);
+
+        final event = ReactionEvent(
+          id: 1,
+          op: ReactionOp.add,
+          emojiName: eg.unicodeEmojiReaction.emojiName,
+          emojiCode: eg.unicodeEmojiReaction.emojiCode,
+          reactionType: eg.unicodeEmojiReaction.reactionType,
+          userId: eg.unicodeEmojiReaction.userId,
+          messageId: originalMessage.id,
+        );
+
+        final message = messageList.messages.single;
+        check(message).reactions.deepEquals([]);
+
+        bool listenersNotified = false;
+
+        messageList.addListener(() { listenersNotified = true; });
+        messageList.maybeUpdateMessageReactions(event);
+
+        check(listenersNotified).isTrue();
+
+        check(message)
+          ..identicalTo(messageList.messages.single)
+          ..reactions.deepEquals([eg.unicodeEmojiReaction]);
+      });
+
+      test('add reaction; message is not in list', () async {
+        final store = await setupStore(stream);
+        final someMessage = eg.streamMessage(id: 1, reactions: []);
+        final messageList = await messageListViewWithMessages([someMessage], store, narrow);
+
+        final event = ReactionEvent(
+          id: 1,
+          op: ReactionOp.add,
+          emojiName: eg.unicodeEmojiReaction.emojiName,
+          emojiCode: eg.unicodeEmojiReaction.emojiCode,
+          reactionType: eg.unicodeEmojiReaction.reactionType,
+          userId: eg.unicodeEmojiReaction.userId,
+          messageId: 1000,
+        );
+
+        check(messageList.messages.single).reactions.deepEquals([]);
+
+        bool listenersNotified = false;
+
+        messageList.addListener(() { listenersNotified = true; });
+        messageList.maybeUpdateMessageReactions(event);
+
+        check(listenersNotified).isFalse();
+
+        check(messageList.messages.single)
+          ..identicalTo(messageList.messages.single)
+          ..reactions.deepEquals([]);
+      });
+
+      test('remove reaction', () async {
+        final store = await setupStore(stream);
+
+        final reaction1 = Reaction(reactionType: ReactionType.unicodeEmoji,
+          emojiName: 'wave',          emojiCode: '1f44b', userId: 1);
+        final reaction2 = Reaction(reactionType: ReactionType.unicodeEmoji, // same emoji, different user
+          emojiName: 'wave',          emojiCode: '1f44b', userId: 2);
+        final reaction3 = Reaction(reactionType: ReactionType.unicodeEmoji, // same user, different emoji
+          emojiName: 'working_on_it', emojiCode: '1f6e0', userId: 1);
+
+        final originalMessage = eg.streamMessage(id: 243, stream: stream,
+          reactions: [reaction1, reaction2, reaction3]);
+        final messageList = await messageListViewWithMessages([originalMessage], store, narrow);
+
+        final event = ReactionEvent(
+          id: 1,
+          op: ReactionOp.remove,
+          emojiName: reaction1.emojiName,
+          emojiCode: reaction1.emojiCode,
+          reactionType: reaction1.reactionType,
+          userId: reaction1.userId,
+          messageId: originalMessage.id,
+        );
+
+        final message = messageList.messages.single;
+        check(message).reactions.deepEquals([reaction1, reaction2, reaction3]);
+
+        bool listenersNotified = false;
+
+        messageList.addListener(() { listenersNotified = true; });
+        messageList.maybeUpdateMessageReactions(event);
+
+        check(listenersNotified).isTrue();
+
+        check(message)
+          ..identicalTo(messageList.messages.single)
+          ..reactions.deepEquals([reaction2, reaction3]);
+      });
+
+      test('remove reaction; message is not in list', () async {
+        final store = await setupStore(stream);
+        final someMessage = eg.streamMessage(id: 1, reactions: []);
+        final messageList = await messageListViewWithMessages([someMessage], store, narrow);
+
+        final event = ReactionEvent(
+          id: 1,
+          op: ReactionOp.remove,
+          emojiName: eg.unicodeEmojiReaction.emojiName,
+          emojiCode: eg.unicodeEmojiReaction.emojiCode,
+          reactionType: eg.unicodeEmojiReaction.reactionType,
+          userId: eg.unicodeEmojiReaction.userId,
+          messageId: 1000,
+        );
+
+        check(messageList.messages.single).reactions.deepEquals([]);
+
+        bool listenersNotified = false;
+
+        messageList.addListener(() { listenersNotified = true; });
+        messageList.maybeUpdateMessageReactions(event);
+
+        check(listenersNotified).isFalse();
+
+        check(messageList.messages.single)
+          ..identicalTo(messageList.messages.single)
+          ..reactions.deepEquals([]);
+      });
+    });
   });
 }