Fix CloudKit reaction parent parsing and round-trip encoding

lib/database/io/attachment.dart

@@ -5,6 +5,7 @@ import 'package:bluebubbles/database/database.dart';
 import 'package:bluebubbles/database/models.dart';
 import 'package:bluebubbles/services/network/backend_service.dart';
 import 'package:bluebubbles/services/rustpush/rustpush_service.dart';
+import 'package:bluebubbles/utils/attachment_guid_utils.dart';
 import 'package:bluebubbles/services/services.dart';
 import 'package:collection/collection.dart';
 import 'package:flutter/foundation.dart';
@@ -64,11 +65,11 @@ class Attachment {
     totalBytes = decoded.totalBytes;
     metadata ??= {};
     metadata!["cloud"] = ckRecordId;
-    if (decoded.guid.startsWith("at")) {
-      var items = decoded.guid.split("_");
+    final owned = parseAppleOwnedAttachmentGuid(decoded.guid);
+    if (owned != null) {
       // format defined in indexedPartsToAttributedBodyDyn
-      var message = Message.findOne(guid: items[2]);
-      guid = "${items[2]}_${items[1]}";
+      var message = Message.findOne(guid: owned.messageGuid);
+      guid = "${owned.messageGuid}_${owned.part}";
       save(message);
     } else {
       guid = decoded.guid;
@@ -77,9 +78,7 @@ class Attachment {
   }
 
   String unconvertAttachmentGuid(String guid) {
-    var items = guid.split("_");
-    if (items.length == 1) return guid;
-    return "at_${items[1]}_${items[0]}";
+    return unconvertAppleAttachmentGuid(guid);
   }
 
   Future<api.AttachmentMeta> getAttachmentMeta() async {

lib/database/io/message.dart

@@ -7,6 +7,7 @@ import 'package:async_task/async_task.dart';
 import 'package:bluebubbles/utils/logger/logger.dart';
 import 'package:bluebubbles/services/network/backend_service.dart';
 import 'package:bluebubbles/services/rustpush/rustpush_service.dart';
+import 'package:bluebubbles/services/rustpush/cloud_sync/cloud_associated_message_parent_reference.dart';
 import 'package:bluebubbles/helpers/helpers.dart';
 import 'package:bluebubbles/database/database.dart';
 import 'package:bluebubbles/database/models.dart';
@@ -1070,7 +1071,10 @@ class Message {
         dateDelivered: dateDelivered != null ? RustPushBBUtils.nsSinceAppleEpoch(dateDelivered!) : 0,
         unk14: 0,
         associatedMessageType: amt,
-        associatedMessageGuid: associatedMessageGuid != null ? "p:$associatedMessagePart/$associatedMessageGuid" : null,
+        associatedMessageGuid: CloudAssociatedMessageParentReference.encode(
+          localMessageGuid: associatedMessageGuid,
+          part: associatedMessagePart,
+        ),
         associatedMessageRangeLength: associatedMessagePart != null ? Message.findOne(guid: associatedMessageGuid!)?.attributedBody[0].runs.firstWhere((r) => r.attributes!.messagePart == associatedMessagePart).range[1] : null,
         associatedMessageRangeLocation: associatedMessagePart != null ? Message.findOne(guid: associatedMessageGuid!)?.attributedBody[0].runs.firstWhere((r) => r.attributes!.messagePart == associatedMessagePart).range[0] : null
       )),
@@ -1155,17 +1159,31 @@ class Message {
     expressiveSendStyleId = proto1.effect;
     dateRead = proto1.dateRead == null || proto1.dateRead == 0 ? null : RustPushBBUtils.fromNsSinceAppleEpoch(proto1.dateRead!);
     dateDelivered = proto1.dateDelivered == null || proto1.dateDelivered == 0 ? null : RustPushBBUtils.fromNsSinceAppleEpoch(proto1.dateDelivered!);
+    associatedMessageType = null;
+    associatedMessageGuid = null;
+    associatedMessagePart = null;
     if (proto1.associatedMessageType != null) {
       if (proto1.associatedMessageType == 2) {
         associatedMessageType = "sticker";
-      } else if (proto1.associatedMessageType! >= 2000 && proto1.associatedMessageType! < 3000) {
-        associatedMessageType = ReactionTypes.toList()[proto1.associatedMessageType! - 2000];
-      } else if (proto1.associatedMessageType! >= 3000 && proto1.associatedMessageType! < 4000) {
-        associatedMessageType = "-${ReactionTypes.toList()[proto1.associatedMessageType! - 3000]}";
+      } else {
+        associatedMessageType =
+            ReactionTypes.fromAssociatedMessageType(proto1.associatedMessageType!);
+      }
+
+      if (associatedMessageType != null &&
+          proto1.associatedMessageGuid != null) {
+        try {
+          final parent = CloudAssociatedMessageParentReference.parse(
+            proto1.associatedMessageGuid!,
+          );
+          associatedMessageGuid = parent.localMessageGuid;
+          associatedMessagePart = parent.part;
+        } on CloudAssociatedMessageParentReferenceFormatException {
+          // Keep the message, but do not attach a malformed reaction to a
+          // potentially unrelated local message.
+        }
       }
     }
-    associatedMessageGuid = proto1.associatedMessageGuid;
-    associatedMessagePart = attributedBody.firstOrNull?.runs.firstWhereOrNull((b) => b.range[0] == proto1.associatedMessageRangeLocation && b.range[1] == proto1.associatedMessageRangeLength)?.attributes?.messagePart;
     guid = c.guid;
     var bits = c.flags.bits();
     isFromMe = (bits & IS_FROM_ME) != 0;

lib/helpers/ui/reaction_helpers.dart

@@ -20,6 +20,18 @@ class ReactionTypes {
   // ignore: non_constant_identifier_names
   static const String STICKERBACK = "stickerback";
 
+  /// Maps Apple's associated-message type to a reaction name.
+  ///
+  /// Unknown indices are not reactions this build can render and return null
+  /// instead of indexing [toList] and throwing a RangeError.
+  static String? fromAssociatedMessageType(int associatedMessageType) {
+    final removed = associatedMessageType >= 3000;
+    final index = associatedMessageType - (removed ? 3000 : 2000);
+    final names = toList();
+    if (index < 0 || index >= names.length) return null;
+    return removed ? "-${names[index]}" : names[index];
+  }
+
   static List<String> toList() {
     return [
       LOVE,
@@ -93,4 +105,4 @@ List<Message> getUniqueReactionMessages(List<Message> messages) {
   }
 
   return output;
-}
+}

lib/services/rustpush/cloud_sync/cloud_associated_message_parent_reference.dart

@@ -0,0 +1,135 @@
+/// A validated CloudKit reference to the local parent of an associated message.
+///
+/// Apple uses `p:<part>/<message-guid>` for a specific message part,
+/// `bp:<part>/<message-guid>` for a bubble or tapback message, and a bare
+/// `<message-guid>` when the reaction targets the whole message. The raw value
+/// is accepted only at this parsing boundary and is never retained in errors.
+final class CloudAssociatedMessageParentReference {
+  const CloudAssociatedMessageParentReference._({
+    required this.part,
+    required this.localMessageGuid,
+  });
+
+  static const int maximumGuidCodeUnits = 512;
+  static const int _maximumPartDigits = 19;
+
+  /// Null when Apple sent a bare GUID for a whole-message reaction.
+  final int? part;
+  final String localMessageGuid;
+
+  /// Encodes the legacy CloudKit parent form used by uploads.
+  static String? encode({String? localMessageGuid, int? part}) {
+    if (localMessageGuid == null) return null;
+    return part == null ? localMessageGuid : 'p:$part/$localMessageGuid';
+  }
+
+  static CloudAssociatedMessageParentReference parse(String encoded) {
+    const prefix = 'p:';
+    const bubblePrefix = 'bp:';
+    const separatorLength = 1;
+    const maximumEncodedCodeUnits =
+        bubblePrefix.length +
+        _maximumPartDigits +
+        separatorLength +
+        maximumGuidCodeUnits;
+    if (encoded.length > maximumEncodedCodeUnits) {
+      throw const CloudAssociatedMessageParentReferenceFormatException();
+    }
+
+    final matchedPrefix = encoded.startsWith(prefix)
+        ? prefix
+        : (encoded.startsWith(bubblePrefix) ? bubblePrefix : null);
+    if (matchedPrefix == null) {
+      if (encoded.contains('/') ||
+          encoded.contains(':') ||
+          !_isValidGuid(encoded)) {
+        throw const CloudAssociatedMessageParentReferenceFormatException();
+      }
+      return CloudAssociatedMessageParentReference._(
+        part: null,
+        localMessageGuid: encoded,
+      );
+    }
+
+    final separator = encoded.indexOf('/', matchedPrefix.length);
+    if (separator == -1 ||
+        encoded.indexOf('/', separator + 1) != -1 ||
+        separator == matchedPrefix.length) {
+      throw const CloudAssociatedMessageParentReferenceFormatException();
+    }
+
+    final encodedPart = encoded.substring(matchedPrefix.length, separator);
+    if (encodedPart.length > _maximumPartDigits ||
+        !_isAsciiDecimal(encodedPart) ||
+        (encodedPart.length > 1 && encodedPart.startsWith('0'))) {
+      throw const CloudAssociatedMessageParentReferenceFormatException();
+    }
+    final part = int.tryParse(encodedPart);
+    if (part == null || part < 0) {
+      throw const CloudAssociatedMessageParentReferenceFormatException();
+    }
+
+    final guid = encoded.substring(separator + 1);
+    if (!_isValidGuid(guid)) {
+      throw const CloudAssociatedMessageParentReferenceFormatException();
+    }
+
+    return CloudAssociatedMessageParentReference._(
+      part: part,
+      localMessageGuid: guid,
+    );
+  }
+
+  static bool _isAsciiDecimal(String value) {
+    for (final codeUnit in value.codeUnits) {
+      if (codeUnit < 0x30 || codeUnit > 0x39) return false;
+    }
+    return value.isNotEmpty;
+  }
+
+  static bool _isValidGuid(String value) {
+    if (value.isEmpty || value.length > maximumGuidCodeUnits) return false;
+    for (final codeUnit in value.codeUnits) {
+      if (codeUnit <= 0x20 ||
+          (codeUnit >= 0x7f && codeUnit <= 0x9f) ||
+          codeUnit == 0x2028 ||
+          codeUnit == 0x2029) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  @override
+  bool operator ==(Object other) =>
+      other is CloudAssociatedMessageParentReference &&
+      other.part == part &&
+      other.localMessageGuid == localMessageGuid;
+
+  @override
+  int get hashCode => Object.hash(part, localMessageGuid);
+
+  @override
+  String toString() => 'CloudAssociatedMessageParentReference(redacted)';
+}
+
+/// A deliberately redacted parse failure.
+final class CloudAssociatedMessageParentReferenceFormatException
+    implements FormatException {
+  const CloudAssociatedMessageParentReferenceFormatException();
+
+  static const String safeCode = 'invalid_associated_message_parent_reference';
+
+  @override
+  String get message => safeCode;
+
+  @override
+  int? get offset => null;
+
+  @override
+  Object? get source => null;
+
+  @override
+  String toString() =>
+      'CloudAssociatedMessageParentReferenceFormatException($safeCode)';
+}

lib/utils/attachment_guid_utils.dart

@@ -0,0 +1,53 @@
+// Apple represents an attachment owned by a message as `at_<part>_<message
+// guid>`, and OpenBubbles stores the same identity locally as
+// `<message guid>_<part>`.
+//
+// A message GUID can contain underscores, so conversion must split only at the
+// separator adjacent to the part number. Invalid identifiers are returned
+// unchanged because they are parsed on the CloudKit download path.
+
+class AppleOwnedAttachmentGuid {
+  const AppleOwnedAttachmentGuid({
+    required this.part,
+    required this.messageGuid,
+  });
+
+  final String part;
+  final String messageGuid;
+}
+
+AppleOwnedAttachmentGuid? parseAppleOwnedAttachmentGuid(String guid) {
+  const prefix = 'at_';
+  if (!guid.startsWith(prefix)) return null;
+  final remainder = guid.substring(prefix.length);
+  final separator = remainder.indexOf('_');
+  if (separator <= 0 || separator >= remainder.length - 1) return null;
+  final part = remainder.substring(0, separator);
+  if (!_isCanonicalDecimal(part)) return null;
+  return AppleOwnedAttachmentGuid(
+    part: part,
+    messageGuid: remainder.substring(separator + 1),
+  );
+}
+
+bool _isCanonicalDecimal(String value) {
+  if (value.isEmpty) return false;
+  for (final unit in value.codeUnits) {
+    if (unit < 0x30 || unit > 0x39) return false;
+  }
+  return value == '0' || value.codeUnitAt(0) != 0x30;
+}
+
+String convertAppleAttachmentGuid(String guid) {
+  final owned = parseAppleOwnedAttachmentGuid(guid);
+  if (owned == null) return guid;
+  return '${owned.messageGuid}_${owned.part}';
+}
+
+String unconvertAppleAttachmentGuid(String guid) {
+  final separator = guid.lastIndexOf('_');
+  if (separator <= 0 || separator >= guid.length - 1) return guid;
+  final part = guid.substring(separator + 1);
+  if (!_isCanonicalDecimal(part)) return guid;
+  return 'at_${part}_${guid.substring(0, separator)}';
+}