message: Handle UpdateMessageEvent for moving.

When a channel (a.k.a stream) or a topic gets updated on a message, we
get a UpdateMessageEvent from the server.

This updates the edit state to show the "edited" or "moved" marker
properly on the messages affected.

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

Author: PIG208

lib/model/message.dart

@@ -139,7 +139,10 @@ class MessageStoreImpl with MessageStore {
   }
 
   void _handleUpdateMessageEventMove(UpdateMessageEvent event) {
-    if (event.origTopic == null) {
+    final bool isChannelMoved = event.newStreamId != null;
+    bool isTopicMoved = event.origTopic != null;
+
+    if (!isTopicMoved && !isChannelMoved) {
       // There was no move.
       assert(() {
         if (event.newStreamId != null && event.origStreamId != null
@@ -162,10 +165,24 @@ class MessageStoreImpl with MessageStore {
       return;
     }
 
+    if (isTopicMoved) {
+      // Eliminate the case when the topic is updated but resolved/unresolved
+      isTopicMoved = MessageEditState.isTopicMoved(event.origTopic!, event.newTopic!);
+    }
+
+    if (!isTopicMoved && !isChannelMoved) 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.
+    for (final messageId in event.messageIds) {
+      final message = messages[messageId];
+      if (message == null) continue;
+      // Do not override the edited marker if the message has also been moved.
+      if (message.editState == MessageEditState.edited) continue;
+      message.editState = MessageEditState.moved;
+    }
   }
 
   void handleDeleteMessageEvent(DeleteMessageEvent event) {

test/example_data.dart

@@ -420,6 +420,35 @@ UpdateMessageEvent updateMessageEditEvent(
   );
 }
 
+UpdateMessageEvent updateMessageMoveEvent(
+  Message origMessage, {
+  int? messageId,
+  int? newStreamId,
+  String? origTopic,
+  String? newTopic,
+}) {
+  messageId ??= origMessage.id;
+  return UpdateMessageEvent(
+    id: 0,
+    userId: selfUser.userId,
+    renderingOnly: false,
+    messageId: messageId,
+    messageIds: [messageId],
+    flags: origMessage.flags,
+    editTimestamp: 1234567890, // TODO generate timestamp
+    origStreamId: origMessage is StreamMessage ? origMessage.streamId : null,
+    newStreamId: newStreamId,
+    propagateMode: null,
+    origTopic: origTopic,
+    newTopic: newTopic,
+    origContent: 'some probably-mismatched old Markdown',
+    origRenderedContent: origMessage.content,
+    content: 'some probably-mismatched new Markdown',
+    renderedContent: origMessage.content,
+    isMeMessage: false,
+  );
+}
+
 UpdateMessageFlagsRemoveEvent updateMessageFlagsRemoveEvent(
   MessageFlag flag,
   Iterable<Message> messages, {

test/model/message_test.dart

@@ -269,6 +269,48 @@ void main() {
     test('rendering-only update does not change timestamp (for old server versions)', () async {
       await checkRenderingOnly(legacy: true);
     });
+
+    group('Handle message edit state update', () {
+      final message = eg.streamMessage();
+
+      Future<void> sendEvent(Message message, UpdateMessageEvent event) async {
+        await prepare();
+        await prepareMessages([message]);
+
+        await store.handleEvent(event);
+        checkNotifiedOnce();
+      }
+
+      test('message not moved update', () async {
+        await sendEvent(message, eg.updateMessageMoveEvent(message));
+        check(store).messages.values.single.editState.equals(MessageEditState.none);
+      });
+
+      test('message topic moved update', () async {
+        await sendEvent(message, eg.updateMessageMoveEvent(message,
+          origTopic: 'old topic',
+          newTopic:  'new topic',
+        ));
+        check(store).messages.values.single.editState.equals(MessageEditState.moved);
+      });
+
+      test('message topic resolved update', () async {
+        await sendEvent(message, eg.updateMessageMoveEvent(message,
+          origTopic: 'new topic',
+          newTopic:  '✔ new topic',
+        ));
+        check(store).messages.values.single.editState.equals(MessageEditState.none);
+      });
+
+      test('message stream moved update', () async {
+        await sendEvent(message, eg.updateMessageMoveEvent(message,
+          origTopic: 'topic',
+          newTopic: 'topic',
+          newStreamId:  20,
+        ));
+        check(store).messages.values.single.editState.equals(MessageEditState.moved);
+      });
+    });
   });
 
   group('handleUpdateMessageFlagsEvent', () {