general chat #3: support alternative styling for topic input on edits/focus/blur

assets/l10n/app_en.arb

@@ -379,6 +379,13 @@
   "@composeBoxTopicHintText":  {
     "description": "Hint text for topic input widget in compose box."
   },
+  "composeBoxEnterTopicOrSkipHintText": "Enter a topic (skip for “{defaultTopicName}”)",
+  "@composeBoxEnterTopicOrSkipHintText":  {
+    "description": "Hint text for topic input widget in compose box when topics are optional.",
+    "placeholders": {
+      "defaultTopicName": {"type": "String", "example": "general chat"}
+    }
+  },
   "composeBoxUploadingFilename": "Uploading {filename}…",
   "@composeBoxUploadingFilename": {
     "description": "Placeholder in compose box showing the specified file is currently uploading.",

lib/api/model/model.dart

@@ -581,11 +581,7 @@ extension type const TopicName(String _value) {
   /// The string this topic is displayed as to the user in our UI.
   ///
   /// At the moment this always equals [apiName].
-  /// In the future this will become null for the "general chat" topic (#1250),
-  /// so that UI code can identify when it needs to represent the topic
-  /// specially in the way prescribed for "general chat".
-  // TODO(#1250) carry out that plan
-  String get displayName => _value;
+  String? get displayName => _value.isEmpty ? null : _value;
 
   /// The key to use for "same topic as" comparisons.
   String canonicalize() => apiName.toLowerCase();

lib/api/route/channels.dart

@@ -7,8 +7,12 @@ part 'channels.g.dart';
 /// https://zulip.com/api/get-stream-topics
 Future<GetStreamTopicsResult> getStreamTopics(ApiConnection connection, {
   required int streamId,
+  bool? allowEmptyTopicName,
 }) {
-  return connection.get('getStreamTopics', GetStreamTopicsResult.fromJson, 'users/me/$streamId/topics', {});
+  assert(allowEmptyTopicName != false, '`allowEmptyTopicName` should only be true or null');
+  return connection.get('getStreamTopics', GetStreamTopicsResult.fromJson, 'users/me/$streamId/topics', {
+    if (allowEmptyTopicName != null) 'allow_empty_topic_name': allowEmptyTopicName,
+  });
 }
 
 @JsonSerializable(fieldRename: FieldRename.snake)

lib/api/route/events.dart

@@ -18,6 +18,7 @@ Future<InitialSnapshot> registerQueue(ApiConnection connection) {
       'user_avatar_url_field_optional': false, // TODO(#254): turn on
       'stream_typing_notifications': true,
       'user_settings_object': true,
+      'empty_topic_name': true,
     },
   });
 }

lib/api/route/messages.dart

@@ -16,9 +16,11 @@ part 'messages.g.dart';
 Future<Message?> getMessageCompat(ApiConnection connection, {
   required int messageId,
   bool? applyMarkdown,
+  bool? allowEmptyTopicName,
 }) async {
   final useLegacyApi = connection.zulipFeatureLevel! < 120;
   if (useLegacyApi) {
+    assert(allowEmptyTopicName == null);
     final response = await getMessages(connection,
       narrow: [ApiNarrowMessageId(messageId)],
       anchor: NumericAnchor(messageId),
@@ -37,6 +39,7 @@ Future<Message?> getMessageCompat(ApiConnection connection, {
       final response = await getMessage(connection,
         messageId: messageId,
         applyMarkdown: applyMarkdown,
+        allowEmptyTopicName: allowEmptyTopicName,
       );
       return response.message;
     } on ZulipApiException catch (e) {
@@ -57,10 +60,13 @@ Future<Message?> getMessageCompat(ApiConnection connection, {
 Future<GetMessageResult> getMessage(ApiConnection connection, {
   required int messageId,
   bool? applyMarkdown,
+  bool? allowEmptyTopicName,
 }) {
+  assert(allowEmptyTopicName != false, '`allowEmptyTopicName` should only be true or null');
   assert(connection.zulipFeatureLevel! >= 120);
   return connection.get('getMessage', GetMessageResult.fromJson, 'messages/$messageId', {
     if (applyMarkdown != null) 'apply_markdown': applyMarkdown,
+    if (allowEmptyTopicName != null) 'allow_empty_topic_name': allowEmptyTopicName,
   });
 }
 
@@ -89,8 +95,10 @@ Future<GetMessagesResult> getMessages(ApiConnection connection, {
   required int numAfter,
   bool? clientGravatar,
   bool? applyMarkdown,
+  bool? allowEmptyTopicName,
   // bool? useFirstUnreadAnchor // omitted because deprecated
 }) {
+  assert(allowEmptyTopicName != false, '`allowEmptyTopicName` should only be true or null');
   return connection.get('getMessages', GetMessagesResult.fromJson, 'messages', {
     'narrow': resolveApiNarrowForServer(narrow, connection.zulipFeatureLevel!),
     'anchor': RawParameter(anchor.toJson()),
@@ -99,6 +107,7 @@ Future<GetMessagesResult> getMessages(ApiConnection connection, {
     'num_after': numAfter,
     if (clientGravatar != null) 'client_gravatar': clientGravatar,
     if (applyMarkdown != null) 'apply_markdown': applyMarkdown,
+    if (allowEmptyTopicName != null) 'allow_empty_topic_name': allowEmptyTopicName,
   });
 }
 

lib/generated/l10n/zulip_localizations.dart

@@ -622,6 +622,12 @@ abstract class ZulipLocalizations {
   /// **'Topic'**
   String get composeBoxTopicHintText;
 
+  /// Hint text for topic input widget in compose box when topics are optional.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a topic (skip for “{defaultTopicName}”)'**
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName);
+
   /// Placeholder in compose box showing the specified file is currently uploading.
   ///
   /// In en, this message translates to:

lib/generated/l10n/zulip_localizations_ar.dart

@@ -316,6 +316,11 @@ class ZulipLocalizationsAr extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Topic';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Uploading $filename…';

lib/generated/l10n/zulip_localizations_en.dart

@@ -316,6 +316,11 @@ class ZulipLocalizationsEn extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Topic';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Uploading $filename…';

lib/generated/l10n/zulip_localizations_ja.dart

@@ -316,6 +316,11 @@ class ZulipLocalizationsJa extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Topic';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Uploading $filename…';

lib/generated/l10n/zulip_localizations_nb.dart

@@ -316,6 +316,11 @@ class ZulipLocalizationsNb extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Topic';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Uploading $filename…';

lib/generated/l10n/zulip_localizations_pl.dart

@@ -323,6 +323,11 @@ class ZulipLocalizationsPl extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Wątek';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Przekazywanie $filename…';

lib/generated/l10n/zulip_localizations_ru.dart

@@ -324,6 +324,11 @@ class ZulipLocalizationsRu extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Тема';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Загрузка $filename…';

lib/generated/l10n/zulip_localizations_sk.dart

@@ -316,6 +316,11 @@ class ZulipLocalizationsSk extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Topic';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Uploading $filename…';

lib/generated/l10n/zulip_localizations_uk.dart

@@ -325,6 +325,11 @@ class ZulipLocalizationsUk extends ZulipLocalizations {
   @override
   String get composeBoxTopicHintText => 'Тема';
 
+  @override
+  String composeBoxEnterTopicOrSkipHintText(String defaultTopicName) {
+    return 'Enter a topic (skip for “$defaultTopicName”)';
+  }
+
   @override
   String composeBoxUploadingFilename(String filename) {
     return 'Завантаження $filename…';

lib/model/autocomplete.dart

@@ -904,7 +904,11 @@ class TopicAutocompleteView extends AutocompleteView<TopicAutocompleteQuery, Top
   Future<void> _fetch() async {
      assert(!_isFetching);
     _isFetching = true;
-    final result = await getStreamTopics(store.connection, streamId: streamId);
+    final result = await getStreamTopics(store.connection, streamId: streamId,
+      allowEmptyTopicName:
+        // TODO(server-10): simplify this condition away
+        store.zulipFeatureLevel >= 334 ? true : null,
+    );
     _topics = result.topics.map((e) => e.name);
     _isFetching = false;
     return _startSearch();
@@ -942,13 +946,11 @@ class TopicAutocompleteQuery extends AutocompleteQuery {
   bool testTopic(TopicName topic, PerAccountStore store) {
     // TODO(#881): Sort by match relevance, like web does.
 
-    // ignore: unnecessary_null_comparison // null topic names soon to be enabled
     if (topic.displayName == null) {
       return store.realmEmptyTopicDisplayName.toLowerCase()
         .contains(raw.toLowerCase());
     }
     return topic.displayName != raw
-      // ignore: unnecessary_non_null_assertion // null topic names soon to be enabled
       && topic.displayName!.toLowerCase().contains(raw.toLowerCase());
   }
 

lib/model/message_list.dart

@@ -510,6 +510,9 @@ class MessageListView with ChangeNotifier, _MessageSequence {
       anchor: AnchorCode.newest,
       numBefore: kMessageListFetchBatchSize,
       numAfter: 0,
+      allowEmptyTopicName:
+        // TODO(server-10): simplify this condition away
+        store.zulipFeatureLevel >= 334 ? true : null,
     );
     if (this.generation > generation) return;
     _adjustNarrowForTopicPermalink(result.messages.firstOrNull);
@@ -582,6 +585,9 @@ class MessageListView with ChangeNotifier, _MessageSequence {
           includeAnchor: false,
           numBefore: kMessageListFetchBatchSize,
           numAfter: 0,
+          allowEmptyTopicName:
+            // TODO(server-10): simplify this condition away
+            store.zulipFeatureLevel >= 334 ? true : null,
         );
       } catch (e) {
         hasFetchError = true;

lib/model/store.dart

@@ -577,6 +577,7 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
   /// be empty otherwise.
   // TODO(server-10) simplify this
   String get realmEmptyTopicDisplayName {
+    assert(zulipFeatureLevel >= 334);
     assert(_realmEmptyTopicDisplayName != null); // TODO(log)
     return _realmEmptyTopicDisplayName ?? 'general chat';
   }

lib/widgets/action_sheet.dart

@@ -304,9 +304,7 @@ void showTopicActionSheet(BuildContext context, {
 
   // TODO: check for other cases that may disallow this action (e.g.: time
   //   limit for editing topics).
-  if (someMessageIdInTopic != null
-      // ignore: unnecessary_null_comparison // null topic names soon to be enabled
-      && topic.displayName != null) {
+  if (someMessageIdInTopic != null && topic.displayName != null) {
     optionButtons.add(ResolveUnresolveButton(pageContext: pageContext,
       topic: topic,
       someMessageIdInTopic: someMessageIdInTopic));

lib/widgets/actions.dart

@@ -257,9 +257,12 @@ abstract final class ZulipAction {
     //   On final failure or success, auto-dismiss the snackbar.
     final zulipLocalizations = ZulipLocalizations.of(context);
     try {
+      final store = PerAccountStoreWidget.of(context);
       fetchedMessage = await getMessageCompat(PerAccountStoreWidget.of(context).connection,
         messageId: messageId,
         applyMarkdown: false,
+        // TODO(server-10): simplify this condition away
+        allowEmptyTopicName: store.zulipFeatureLevel >= 334 ? true : null,
       );
       if (fetchedMessage == null) {
         errorMessage = zulipLocalizations.errorMessageDoesNotSeemToExist;

lib/widgets/autocomplete.dart

@@ -416,13 +416,11 @@ class TopicAutocomplete extends AutocompleteField<TopicAutocompleteQuery, TopicA
   @override
   Widget buildItem(BuildContext context, int index, TopicAutocompleteResult option) {
     final Widget child;
-    // ignore: unnecessary_null_comparison // null topic names soon to be enabled
     if (option.topic.displayName == null) {
       final store = PerAccountStoreWidget.of(context);
       child = Text(store.realmEmptyTopicDisplayName,
         style: const TextStyle(fontStyle: FontStyle.italic));
     } else {
-      // ignore: unnecessary_non_null_assertion // null topic names soon to be enabled
       child = Text(option.topic.displayName!);
     }