api: Add RealmUpdateEvent and guest DM warning flag

- Add realmEnableGuestUserDmWarning to PerAccountStore
- Handle RealmUpdateEvent to keep setting in sync with server
- Support feature level 348+ for realm configuration

Author: chimnayajith

lib/api/model/events.dart

@@ -67,6 +67,11 @@ sealed class Event {
       case 'submessage': return SubmessageEvent.fromJson(json);
       case 'typing': return TypingEvent.fromJson(json);
       case 'reaction': return ReactionEvent.fromJson(json);
+      case 'realm':
+        switch(json['op'] as String){
+          case 'update': return RealmUpdateEvent.fromJson(json);
+          default: return UnexpectedEvent.fromJson(json);
+        }
       case 'heartbeat': return HeartbeatEvent.fromJson(json);
       // TODO add many more event types
       default: return UnexpectedEvent.fromJson(json);
@@ -1151,6 +1156,46 @@ enum ReactionOp {
   remove,
 }
 
+/// A Zulip event of type `realm`, with op `update`.
+///
+/// This is the simpler of two possible event types sent when realm configuration changes.
+/// It updates a single realm setting at a time.
+///
+/// See: https://zulip.com/api/get-events#realm-update
+@JsonSerializable(fieldRename: FieldRename.snake)
+class RealmUpdateEvent extends Event {
+  @override
+  @JsonKey(includeToJson: true)
+  String get type => 'realm';
+
+  @JsonKey(includeToJson: true)
+  String get op => 'update';
+
+  @JsonKey(unknownEnumValue: JsonKey.nullForUndefinedEnumValue)
+  final RealmPropertyName? property;
+
+  final dynamic value;
+
+  RealmUpdateEvent({
+    required super.id,
+    required this.property,
+    required this.value,
+  });
+
+  factory RealmUpdateEvent.fromJson(Map<String, dynamic> json) =>
+    _$RealmUpdateEventFromJson(json);
+
+  @override
+  Map<String, dynamic> toJson() => _$RealmUpdateEventToJson(this);
+}
+
+/// As in [RealmUpdateEvent.property].
+@JsonEnum(fieldRename: FieldRename.snake)
+enum RealmPropertyName {
+  @JsonValue('enable_guest_user_dm_warning')
+  realmEnableGuestUserDmWarning,
+}
+
 /// 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

@@ -86,6 +86,9 @@ class InitialSnapshot {
 
   final int maxFileUploadSizeMib;
 
+  @JsonKey(defaultValue: false) // TODO(server-10): Remove default
+  final bool realmEnableGuestUserDmWarning;
+
   final Uri? serverEmojiDataUrl; // TODO(server-6)
 
   final String? realmEmptyTopicDisplayName; // TODO(server-10)
@@ -144,6 +147,7 @@ class InitialSnapshot {
     required this.realmMessageContentEditLimitSeconds,
     required this.realmDefaultExternalAccounts,
     required this.maxFileUploadSizeMib,
+    required this.realmEnableGuestUserDmWarning,
     required this.serverEmojiDataUrl,
     required this.realmEmptyTopicDisplayName,
     required this.realmUsers,

lib/api/model/initial_snapshot.dart

@@ -471,6 +471,7 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
       realmMandatoryTopics: initialSnapshot.realmMandatoryTopics,
       realmWaitingPeriodThreshold: initialSnapshot.realmWaitingPeriodThreshold,
       maxFileUploadSizeMib: initialSnapshot.maxFileUploadSizeMib,
+      realmEnableGuestUserDmWarning: initialSnapshot.realmEnableGuestUserDmWarning,
       realmEmptyTopicDisplayName: initialSnapshot.realmEmptyTopicDisplayName,
       realmAllowMessageEditing: initialSnapshot.realmAllowMessageEditing,
       realmMessageContentEditLimitSeconds: initialSnapshot.realmMessageContentEditLimitSeconds,
@@ -510,6 +511,7 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
     required this.realmMandatoryTopics,
     required this.realmWaitingPeriodThreshold,
     required this.maxFileUploadSizeMib,
+    required this.realmEnableGuestUserDmWarning,
     required String? realmEmptyTopicDisplayName,
     required this.realmAllowMessageEditing,
     required this.realmMessageContentEditLimitSeconds,
@@ -571,6 +573,13 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
   final int? realmMessageContentEditLimitSeconds; // TODO(#668): update this realm setting
   final int maxFileUploadSizeMib; // No event for this.
 
+  /// Whether to show a warning when composing a DM to a guest user.
+  ///
+  /// See: https://zulip.com/api/get-events-types
+  /// Changes: Added in Zulip 10.0 (feature level 348).
+  // TODO(server-10): Remove default
+  bool realmEnableGuestUserDmWarning = false;
+
   /// The display name to use for empty topics.
   ///
   /// This should only be accessed when FL >= 334, since topics cannot
@@ -899,6 +908,13 @@ class PerAccountStore extends PerAccountStoreBase with ChangeNotifier, EmojiStor
         assert(debugLog("server event: reaction/${event.op}"));
         _messages.handleReactionEvent(event);
 
+      case RealmUpdateEvent():
+        assert(debugLog("server event: realm/${event.op}"));
+        if (event.property == RealmPropertyName.realmEnableGuestUserDmWarning) {
+          realmEnableGuestUserDmWarning = event.value as bool;
+          notifyListeners();
+        }
+        break;
       case UnexpectedEvent():
         assert(debugLog("server event: ${jsonEncode(event.toJson())}")); // TODO log better
     }

lib/api/model/initial_snapshot.g.dart

@@ -920,6 +920,7 @@ InitialSnapshot initialSnapshot({
   int? realmMessageContentEditLimitSeconds,
   Map<String, RealmDefaultExternalAccount>? realmDefaultExternalAccounts,
   int? maxFileUploadSizeMib,
+  bool? realmEnableGuestUserDmWarning,
   Uri? serverEmojiDataUrl,
   String? realmEmptyTopicDisplayName,
   List<User>? realmUsers,
@@ -959,6 +960,7 @@ InitialSnapshot initialSnapshot({
     realmMessageContentEditLimitSeconds: realmMessageContentEditLimitSeconds ?? 600,
     realmDefaultExternalAccounts: realmDefaultExternalAccounts ?? {},
     maxFileUploadSizeMib: maxFileUploadSizeMib ?? 25,
+    realmEnableGuestUserDmWarning: realmEnableGuestUserDmWarning ?? false,
     serverEmojiDataUrl: serverEmojiDataUrl
       ?? realmUrl.replace(path: '/static/emoji.json'),
     realmEmptyTopicDisplayName: realmEmptyTopicDisplayName ?? defaultRealmEmptyTopicDisplayName,