Add skeleton of handling a move UpdateMessageEvent

lib/api/model/events.dart

@@ -611,6 +611,7 @@ class MessageEvent extends Event {
 @JsonSerializable(fieldRename: FieldRename.snake)
 class UpdateMessageEvent extends Event {
   @override
+  @JsonKey(includeToJson: true)
   String get type => 'update_message';
 
   final int? userId; // TODO(server-5)
@@ -683,6 +684,7 @@ enum PropagateMode {
 @JsonSerializable(fieldRename: FieldRename.snake)
 class DeleteMessageEvent extends Event {
   @override
+  @JsonKey(includeToJson: true)
   String get type => 'delete_message';
 
   final List<int> messageIds;

lib/model/message.dart

@@ -1,5 +1,6 @@
 import '../api/model/events.dart';
 import '../api/model/model.dart';
+import '../log.dart';
 import 'message_list.dart';
 
 /// The portion of [PerAccountStore] for messages and message lists.
@@ -93,32 +94,42 @@ class MessageStoreImpl with MessageStore {
   }
 
   void handleUpdateMessageEvent(UpdateMessageEvent event) {
+    assert(event.messageIds.contains(event.messageId), "See https://github.com/zulip/zulip-flutter/pull/753#discussion_r1649463633");
+    _handleUpdateMessageEventTimestamp(event);
     _handleUpdateMessageEventContent(event);
-    // TODO(#150): Handle message moves.  The views' recipient headers
-    //   may need updating, and consequently showSender too.
+    _handleUpdateMessageEventMove(event);
+    for (final view in _messageListViews) {
+      view.notifyListenersIfAnyMessagePresent(event.messageIds);
+    }
   }
 
-  void _handleUpdateMessageEventContent(UpdateMessageEvent event) {
-    final message = messages[event.messageId];
-    if (message == null) return;
-
+  void _handleUpdateMessageEventTimestamp(UpdateMessageEvent event) {
     // TODO(server-5): Cut this fallback; rely on renderingOnly from FL 114
     final isRenderingOnly = event.renderingOnly ?? (event.userId == null);
-    if (event.editTimestamp != null && !isRenderingOnly) {
+    if (event.editTimestamp == null || isRenderingOnly) {
       // A rendering-only update gets omitted from the message edit history,
       // and [Message.lastEditTimestamp] is the last timestamp of that history.
       // So on a rendering-only update, the timestamp doesn't get updated.
+      return;
+    }
+
+    for (final messageId in event.messageIds) {
+      final message = messages[messageId];
+      if (message == null) continue;
       message.lastEditTimestamp = event.editTimestamp;
     }
+  }
 
-    message.flags = event.flags;
+  void _handleUpdateMessageEventContent(UpdateMessageEvent event) {
+    final message = messages[event.messageId];
+    if (message == null) return;
 
+    message.flags = event.flags;
     if (event.renderedContent != null) {
       assert(message.contentType == 'text/html',
         "Message contentType was ${message.contentType}; expected text/html.");
       message.content = event.renderedContent!;
     }
-
     if (event.isMeMessage != null) {
       message.isMeMessage = event.isMeMessage!;
     }
@@ -128,6 +139,41 @@ class MessageStoreImpl with MessageStore {
     }
   }
 
+  void _handleUpdateMessageEventMove(UpdateMessageEvent event) {
+    // The interaction between the fields of these events are a bit tricky.
+    // For reference, see: https://zulip.com/api/get-events#update_message
+
+    if (event.origTopic == null) {
+      // There was no move.
+      assert(() {
+        if (event.newStreamId != null && event.origStreamId != null
+            && event.newStreamId != event.origStreamId) {
+          // This should be impossible; `orig_subject` (aka origTopic) is
+          // documented to be present when either the stream or topic changed.
+          debugLog('Malformed UpdateMessageEvent: stream move but no origTopic'); // TODO(log)
+        }
+        return true;
+      }());
+      return;
+    }
+
+    if (event.newTopic == null) {
+      // The `subject` field (aka newTopic) is documented to be present on moves.
+      assert(debugLog('Malformed UpdateMessageEvent: move but no newTopic')); // TODO(log)
+      return;
+    }
+    if (event.origStreamId == null) {
+      // The `stream_id` field (aka origStreamId) is documented to be present on moves.
+      assert(debugLog('Malformed UpdateMessageEvent: move but no origStreamId')); // TODO(log)
+      return;
+    }
+
+    // final newStreamId = event.newStreamId; // null if topic-only move
+    // final newTopic = event.newTopic!;
+    // TODO(#150): Handle message moves.  The views' recipient headers
+    //   may need updating, and consequently showSender too.
+  }
+
   void handleDeleteMessageEvent(DeleteMessageEvent event) {
     // TODO handle DeleteMessageEvent, particularly in MessageListView
   }

lib/model/message_list.dart

@@ -467,11 +467,14 @@ class MessageListView with ChangeNotifier, _MessageSequence {
     }
   }
 
+  /// Update data derived from the content of the given message.
+  ///
+  /// This does not notify listeners.
+  /// The caller should ensure that happens later.
   void messageContentChanged(int messageId) {
     final index = _findMessageWithId(messageId);
     if (index != -1) {
       _reparseContent(index);
-      notifyListeners();
     }
   }
 

test/model/message_test.dart

@@ -162,6 +162,34 @@ void main() {
   });
 
   group('handleUpdateMessageEvent', () {
+    test('update timestamps on all messages', () async {
+      const t1 = 1718748879;
+      const t2 = t1 + 60;
+      final message1 = eg.streamMessage(lastEditTimestamp: null);
+      final message2 = eg.streamMessage(lastEditTimestamp: t1);
+      // This event is a bit artificial, but convenient.
+      // TODO use a realistic move-messages event here
+      final updateEvent = Event.fromJson({
+        ...eg.updateMessageEditEvent(message1).toJson(),
+        'message_ids': [message1.id, message2.id],
+        'edit_timestamp': t2,
+      }) as UpdateMessageEvent;
+      await prepare();
+      await prepareMessages([message1, message2]);
+
+      check(store).messages.values.unorderedMatches(<Condition<Message>>[
+        (it) => it.lastEditTimestamp.isNull,
+        (it) => it.lastEditTimestamp.equals(t1),
+      ]);
+
+      await store.handleEvent(updateEvent);
+      checkNotifiedOnce();
+      check(store).messages.values.unorderedMatches(<Condition<Message>>[
+        (it) => it.lastEditTimestamp.equals(t2),
+        (it) => it.lastEditTimestamp.equals(t2),
+      ]);
+    });
+
     test('update a message', () async {
       final originalMessage = eg.streamMessage(
         content: "<p>Hello, world</p>");