Fetch server emoji data (about Unicode emoji)

lib/api/core.dart

@@ -116,12 +116,24 @@ class ApiConnection {
   bool _isOpen = true;
 
   Future<T> send<T>(String routeName, T Function(Map<String, dynamic>) fromJson,
-      http.BaseRequest request, {String? overrideUserAgent}) async {
+    http.BaseRequest request, {
+    bool useAuth = true,
+    String? overrideUserAgent,
+  }) async {
     assert(_isOpen);
 
     assert(debugLog("${request.method} ${request.url}"));
 
-    addAuth(request);
+    if (useAuth) {
+      if (request.url.origin != realmUrl.origin) {
+        // No caller should get here with a URL whose origin isn't the realm's.
+        // If this does happen, it's important not to proceed, because we'd be
+        // sending the user's auth credentials.
+        throw StateError("ApiConnection.send called with useAuth on off-realm URL");
+      }
+      addAuth(request);
+    }
+
     if (overrideUserAgent != null) {
       request.headers['User-Agent'] = overrideUserAgent;
     } else {

lib/api/model/initial_snapshot.dart

@@ -68,6 +68,8 @@ class InitialSnapshot {
 
   final int maxFileUploadSizeMib;
 
+  final Uri? serverEmojiDataUrl; // TODO(server-6)
+
   @JsonKey(readValue: _readUsersIsActiveFallbackTrue)
   final List<User> realmUsers;
   @JsonKey(readValue: _readUsersIsActiveFallbackFalse)
@@ -117,6 +119,7 @@ class InitialSnapshot {
     required this.userTopics,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
+    required this.serverEmojiDataUrl,
     required this.realmUsers,
     required this.realmNonActiveUsers,
     required this.crossRealmBots,

lib/api/route/realm.dart

@@ -1,6 +1,8 @@
+import 'package:http/http.dart' as http;
 import 'package:json_annotation/json_annotation.dart';
 
 import '../core.dart';
+import '../model/initial_snapshot.dart';
 
 part 'realm.g.dart';
 
@@ -94,3 +96,49 @@ class ExternalAuthenticationMethod {
 
   Map<String, dynamic> toJson() => _$ExternalAuthenticationMethodToJson(this);
 }
+
+/// Fetch data from the URL described by [InitialSnapshot.serverEmojiDataUrl].
+///
+/// This request is unauthenticated, and the URL need not be on the realm.
+/// The given [ApiConnection] is used for providing a `User-Agent` header
+/// and for handling errors.
+///
+/// For docs, search for "server_emoji"
+/// in <https://zulip.com/api/register-queue>.
+Future<ServerEmojiData> fetchServerEmojiData(ApiConnection connection, {
+  required Uri emojiDataUrl,
+}) {
+  // TODO(#950): cache server responses on fetchServerEmojiData
+
+  // This nontraditional endpoint doesn't conform to all the usual Zulip API
+  // protocols: https://zulip.com/api/rest-error-handling
+  // notably the `{ code, msg, result }` format for errors.
+  // So in the case of an error, the generic Zulip API error-handling logic
+  // in [ApiConnection.send] will throw [MalformedServerResponseException]
+  // in some cases where "malformed" isn't quite the right description.
+  // We'll just tolerate that.
+  // If it really mattered, we could refactor [ApiConnection] to accommodate.
+  //
+  // Similarly, there's no `"result": "success"` in the response.
+  // Fortunately none of our code looks for that in the first place.
+  return connection.send('fetchServerEmojiData', ServerEmojiData.fromJson,
+    useAuth: false,
+    http.Request('GET', emojiDataUrl));
+}
+
+/// The server's data describing its list of Unicode emoji
+/// and its names for them.
+///
+/// For docs, search for "server_emoji"
+/// in <https://zulip.com/api/register-queue>.
+@JsonSerializable(fieldRename: FieldRename.snake)
+class ServerEmojiData {
+  final Map<String, List<String>> codeToNames;
+
+  ServerEmojiData({required this.codeToNames});
+
+  factory ServerEmojiData.fromJson(Map<String, dynamic> json) =>
+    _$ServerEmojiDataFromJson(json);
+
+  Map<String, dynamic> toJson() => _$ServerEmojiDataToJson(this);
+}

lib/model/emoji.dart

@@ -1,6 +1,7 @@
 import '../api/model/events.dart';
 import '../api/model/initial_snapshot.dart';
 import '../api/model/model.dart';
+import '../api/route/realm.dart';
 
 /// An emoji, described by how to display it in the UI.
 sealed class EmojiDisplay {
@@ -61,6 +62,12 @@ mixin EmojiStore {
     required String emojiCode,
     required String emojiName,
   });
+
+  // TODO cut debugServerEmojiData once we can query for lists of emoji;
+  //   have tests make those queries end-to-end
+  Map<String, List<String>>? get debugServerEmojiData;
+
+  void setServerEmojiData(ServerEmojiData data);
 }
 
 /// The implementation of [EmojiStore] that does the work.
@@ -72,7 +79,7 @@ class EmojiStoreImpl with EmojiStore {
   EmojiStoreImpl({
     required this.realmUrl,
     required this.realmEmoji,
-  });
+  }) : _serverEmojiData = null; // TODO(#974) maybe start from a hard-coded baseline
 
   /// The same as [PerAccountStore.realmUrl].
   final Uri realmUrl;
@@ -131,6 +138,21 @@ class EmojiStoreImpl with EmojiStore {
     );
   }
 
+  @override
+  Map<String, List<String>>? get debugServerEmojiData => _serverEmojiData;
+
+  /// The server's list of Unicode emoji and names for them,
+  /// from [ServerEmojiData].
+  ///
+  /// This is null until [UpdateMachine.fetchEmojiData] finishes
+  /// retrieving the data.
+  Map<String, List<String>>? _serverEmojiData;
+
+  @override
+  void setServerEmojiData(ServerEmojiData data) {
+    _serverEmojiData = data.codeToNames;
+  }
+
   void handleRealmEmojiUpdateEvent(RealmEmojiUpdateEvent event) {
     realmEmoji = event.realmEmoji;
   }

lib/model/store.dart

@@ -16,6 +16,7 @@ import '../api/model/model.dart';
 import '../api/route/events.dart';
 import '../api/route/messages.dart';
 import '../api/backoff.dart';
+import '../api/route/realm.dart';
 import '../log.dart';
 import '../notifications/receive.dart';
 import 'autocomplete.dart';
@@ -345,6 +346,15 @@ class PerAccountStore extends ChangeNotifier with EmojiStore, ChannelStore, Mess
       emojiType: emojiType, emojiCode: emojiCode, emojiName: emojiName);
   }
 
+  @override
+  Map<String, List<String>>? get debugServerEmojiData => _emoji.debugServerEmojiData;
+
+  @override
+  void setServerEmojiData(ServerEmojiData data) {
+    _emoji.setServerEmojiData(data);
+    notifyListeners();
+  }
+
   EmojiStoreImpl _emoji;
 
   ////////////////////////////////
@@ -746,9 +756,15 @@ class UpdateMachine {
     final updateMachine = UpdateMachine.fromInitialSnapshot(
       store: store, initialSnapshot: initialSnapshot);
     updateMachine.poll();
+    if (initialSnapshot.serverEmojiDataUrl != null) {
+      // TODO(server-6): If the server is ancient, just skip trying to have
+      //   a list of its emoji.  (The old servers that don't provide
+      //   serverEmojiDataUrl are already unsupported at time of writing.)
+      unawaited(updateMachine.fetchEmojiData(initialSnapshot.serverEmojiDataUrl!));
+    }
     // TODO do registerNotificationToken before registerQueue:
     //   https://github.com/zulip/zulip-flutter/pull/325#discussion_r1365982807
-    updateMachine.registerNotificationToken();
+    unawaited(updateMachine.registerNotificationToken());
     return updateMachine;
   }
 
@@ -772,6 +788,43 @@ class UpdateMachine {
     }
   }
 
+  /// Fetch emoji data from the server, and update the store with the result.
+  ///
+  /// This functions a lot like [registerQueue] and the surrounding logic
+  /// in [load] above, but it's unusual in that we've separated it out.
+  /// Effectively it's data that *would have* been in the [registerQueue]
+  /// response, except that we pulled it out to its own endpoint as part of
+  /// a caching strategy, because the data changes infrequently.
+  ///
+  /// Conveniently (a) this deferred fetch doesn't cause any fetch/event race,
+  /// because this data doesn't get updated by events anyway (it can change
+  /// only on a server restart); and (b) we don't need this data for displaying
+  /// messages or anything else, only for certain UIs like the emoji picker,
+  /// so it's fine that we go without it for a while.
+  Future<void> fetchEmojiData(Uri serverEmojiDataUrl) async {
+    if (!debugEnableFetchEmojiData) return;
+    BackoffMachine? backoffMachine;
+    ServerEmojiData data;
+    while (true) {
+      try {
+        data = await fetchServerEmojiData(store.connection,
+          emojiDataUrl: serverEmojiDataUrl);
+        assert(debugLog('Got emoji data: ${data.codeToNames.length} emoji'));
+        break;
+      } catch (e) {
+        assert(debugLog('Error fetching emoji data: $e\n' // TODO(log)
+          'Backing off, then will retry…'));
+        // The emoji data is a lot less urgent than the initial fetch,
+        // or even the event-queue poll request.  So wait longer.
+        backoffMachine ??= BackoffMachine(firstBound: const Duration(seconds: 2),
+                                          maxBound: const Duration(minutes: 2));
+        await backoffMachine.wait();
+      }
+    }
+
+    store.setServerEmojiData(data);
+  }
+
   Completer<void>? _debugLoopSignal;
 
   /// In debug mode, causes the polling loop to pause before the next
@@ -865,26 +918,6 @@ class UpdateMachine {
     }
   }
 
-  /// In debug mode, controls whether [registerNotificationToken] should
-  /// have its normal effect.
-  ///
-  /// Outside of debug mode, this is always true and the setter has no effect.
-  static bool get debugEnableRegisterNotificationToken {
-    bool result = true;
-    assert(() {
-      result = _debugEnableRegisterNotificationToken;
-      return true;
-    }());
-    return result;
-  }
-  static bool _debugEnableRegisterNotificationToken = true;
-  static set debugEnableRegisterNotificationToken(bool value) {
-    assert(() {
-      _debugEnableRegisterNotificationToken = value;
-      return true;
-    }());
-  }
-
   /// Send this client's notification token to the server, now and if it changes.
   ///
   /// TODO The returned future isn't especially meaningful (it may or may not
@@ -910,6 +943,46 @@ class UpdateMachine {
     NotificationService.instance.token.removeListener(_registerNotificationToken);
   }
 
+  /// In debug mode, controls whether [fetchEmojiData] should
+  /// have its normal effect.
+  ///
+  /// Outside of debug mode, this is always true and the setter has no effect.
+  static bool get debugEnableFetchEmojiData {
+    bool result = true;
+    assert(() {
+      result = _debugEnableFetchEmojiData;
+      return true;
+    }());
+    return result;
+  }
+  static bool _debugEnableFetchEmojiData = true;
+  static set debugEnableFetchEmojiData(bool value) {
+    assert(() {
+      _debugEnableFetchEmojiData = value;
+      return true;
+    }());
+  }
+
+  /// In debug mode, controls whether [registerNotificationToken] should
+  /// have its normal effect.
+  ///
+  /// Outside of debug mode, this is always true and the setter has no effect.
+  static bool get debugEnableRegisterNotificationToken {
+    bool result = true;
+    assert(() {
+      result = _debugEnableRegisterNotificationToken;
+      return true;
+    }());
+    return result;
+  }
+  static bool _debugEnableRegisterNotificationToken = true;
+  static set debugEnableRegisterNotificationToken(bool value) {
+    assert(() {
+      _debugEnableRegisterNotificationToken = value;
+      return true;
+    }());
+  }
+
   @override
   String toString() => '${objectRuntimeType(this, 'UpdateMachine')}#${shortHash(this)}';
 }