leave groups works now

lib/src/database/daos/groups.dao.dart

@@ -38,10 +38,21 @@ class GroupsDao extends DatabaseAccessor<TwonlyDB> with _$GroupsDaoMixin {
   }
 
   Future<List<GroupMember>> getGroupMembers(String groupId) async {
-    return (select(groupMembers)..where((t) => t.groupId.equals(groupId)))
+    return (select(groupMembers)
+          ..where(
+            (t) =>
+                t.groupId.equals(groupId) &
+                t.memberState.equals(MemberState.leftGroup.name).not(),
+          ))
         .get();
   }
 
+  Future<GroupMember?> getGroupMemberByPublicKey(Uint8List publicKey) async {
+    return (select(groupMembers)
+          ..where((t) => t.groupPublicKey.equals(publicKey)))
+        .getSingleOrNull();
+  }
+
   Future<Group?> createNewGroup(GroupsCompanion group) async {
     return _insertGroup(group);
   }

lib/src/localization/app_de.arb

@@ -797,5 +797,12 @@
     "notificationTitleUnknownUser": "Jemand",
     "notificationCategoryMessageTitle": "Nachrichten",
     "notificationCategoryMessageDesc": "Nachrichten von anderen Benutzern.",
-    "groupContextMenuDeleteGroup": "Dadurch werden alle Nachrichten in diesem Chat dauerhaft gelöscht."
+    "groupContextMenuDeleteGroup": "Dadurch werden alle Nachrichten in diesem Chat dauerhaft gelöscht.",
+    "groupYouAreNowLongerAMember": "Du bist nicht mehr Mitglied dieser Gruppe.",
+    "groupNetworkIssue": "Netzwerkproblem. Bitte probiere es später noch einmal.",
+    "leaveGroupSelectOtherAdminTitle": "Einen Admin auswählen",
+    "leaveGroupSelectOtherAdminBody": "Um die Gruppe zu verlassen, musst du zuerst einen neuen Administrator auswählen.",
+    "leaveGroupSureTitle": "Gruppe verlassen",
+    "leaveGroupSureBody": "Willst du die Gruppe wirklich verlassen?",
+    "leaveGroupSureOkBtn": "Gruppe verlassen"
 }

lib/src/localization/app_en.arb

@@ -575,5 +575,12 @@
   "notificationTitleUnknownUser": "Someone",
   "notificationCategoryMessageTitle": "Messages",
   "notificationCategoryMessageDesc": "Messages from other users.",
-  "groupContextMenuDeleteGroup": "This will permanently delete all messages in this chat."
+  "groupContextMenuDeleteGroup": "This will permanently delete all messages in this chat.",
+  "groupYouAreNowLongerAMember": "You are no longer part of this group.",
+  "groupNetworkIssue": "Network issue. Try again later.",
+  "leaveGroupSelectOtherAdminTitle": "Select another admin",
+  "leaveGroupSelectOtherAdminBody": "To leave the group, you must first select a new administrator.",
+  "leaveGroupSureTitle": "Leave group",
+  "leaveGroupSureBody": "Do you really want to leave the group?",
+  "leaveGroupSureOkBtn": "Leave group"
 }

lib/src/localization/generated/app_localizations.dart

@@ -2557,6 +2557,48 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'This will permanently delete all messages in this chat.'**
   String get groupContextMenuDeleteGroup;
+
+  /// No description provided for @groupYouAreNowLongerAMember.
+  ///
+  /// In en, this message translates to:
+  /// **'You are no longer part of this group.'**
+  String get groupYouAreNowLongerAMember;
+
+  /// No description provided for @groupNetworkIssue.
+  ///
+  /// In en, this message translates to:
+  /// **'Network issue. Try again later.'**
+  String get groupNetworkIssue;
+
+  /// No description provided for @leaveGroupSelectOtherAdminTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Select another admin'**
+  String get leaveGroupSelectOtherAdminTitle;
+
+  /// No description provided for @leaveGroupSelectOtherAdminBody.
+  ///
+  /// In en, this message translates to:
+  /// **'To leave the group, you must first select a new administrator.'**
+  String get leaveGroupSelectOtherAdminBody;
+
+  /// No description provided for @leaveGroupSureTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Leave group'**
+  String get leaveGroupSureTitle;
+
+  /// No description provided for @leaveGroupSureBody.
+  ///
+  /// In en, this message translates to:
+  /// **'Do you really want to leave the group?'**
+  String get leaveGroupSureBody;
+
+  /// No description provided for @leaveGroupSureOkBtn.
+  ///
+  /// In en, this message translates to:
+  /// **'Leave group'**
+  String get leaveGroupSureOkBtn;
 }
 
 class _AppLocalizationsDelegate

lib/src/localization/generated/app_localizations_de.dart

@@ -1397,4 +1397,28 @@ class AppLocalizationsDe extends AppLocalizations {
   @override
   String get groupContextMenuDeleteGroup =>
       'Dadurch werden alle Nachrichten in diesem Chat dauerhaft gelöscht.';
+
+  @override
+  String get groupYouAreNowLongerAMember =>
+      'Du bist nicht mehr Mitglied dieser Gruppe.';
+
+  @override
+  String get groupNetworkIssue =>
+      'Netzwerkproblem. Bitte probiere es später noch einmal.';
+
+  @override
+  String get leaveGroupSelectOtherAdminTitle => 'Einen Admin auswählen';
+
+  @override
+  String get leaveGroupSelectOtherAdminBody =>
+      'Um die Gruppe zu verlassen, musst du zuerst einen neuen Administrator auswählen.';
+
+  @override
+  String get leaveGroupSureTitle => 'Gruppe verlassen';
+
+  @override
+  String get leaveGroupSureBody => 'Willst du die Gruppe wirklich verlassen?';
+
+  @override
+  String get leaveGroupSureOkBtn => 'Gruppe verlassen';
 }

lib/src/localization/generated/app_localizations_en.dart

@@ -1389,4 +1389,27 @@ class AppLocalizationsEn extends AppLocalizations {
   @override
   String get groupContextMenuDeleteGroup =>
       'This will permanently delete all messages in this chat.';
+
+  @override
+  String get groupYouAreNowLongerAMember =>
+      'You are no longer part of this group.';
+
+  @override
+  String get groupNetworkIssue => 'Network issue. Try again later.';
+
+  @override
+  String get leaveGroupSelectOtherAdminTitle => 'Select another admin';
+
+  @override
+  String get leaveGroupSelectOtherAdminBody =>
+      'To leave the group, you must first select a new administrator.';
+
+  @override
+  String get leaveGroupSureTitle => 'Leave group';
+
+  @override
+  String get leaveGroupSureBody => 'Do you really want to leave the group?';
+
+  @override
+  String get leaveGroupSureOkBtn => 'Leave group';
 }

lib/src/model/protobuf/api/http/http_requests.pb.dart

@@ -373,10 +373,10 @@ class NewGroupState extends $pb.GeneratedMessage {
   factory NewGroupState.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
 
   static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'NewGroupState', package: const $pb.PackageName(_omitMessageNames ? '' : 'http_requests'), createEmptyInstance: create)
-    ..aOS(1, _omitFieldNames ? '' : 'groupId', protoName: 'groupId')
+    ..aOS(1, _omitFieldNames ? '' : 'groupId')
-    ..a<$fixnum.Int64>(2, _omitFieldNames ? '' : 'versionId', $pb.PbFieldType.OU6, protoName: 'versionId', defaultOrMaker: $fixnum.Int64.ZERO)
+    ..a<$fixnum.Int64>(2, _omitFieldNames ? '' : 'versionId', $pb.PbFieldType.OU6, defaultOrMaker: $fixnum.Int64.ZERO)
-    ..a<$core.List<$core.int>>(4, _omitFieldNames ? '' : 'encryptedGroupState', $pb.PbFieldType.OY)
+    ..a<$core.List<$core.int>>(3, _omitFieldNames ? '' : 'encryptedGroupState', $pb.PbFieldType.OY)
-    ..a<$core.List<$core.int>>(5, _omitFieldNames ? '' : 'publicKey', $pb.PbFieldType.OY)
+    ..a<$core.List<$core.int>>(4, _omitFieldNames ? '' : 'publicKey', $pb.PbFieldType.OY)
     ..hasRequiredFields = false
   ;
 
@@ -419,29 +419,202 @@ class NewGroupState extends $pb.GeneratedMessage {
   @$pb.TagNumber(2)
   void clearVersionId() => clearField(2);
 
-  @$pb.TagNumber(4)
+  @$pb.TagNumber(3)
   $core.List<$core.int> get encryptedGroupState => $_getN(2);
-  @$pb.TagNumber(4)
+  @$pb.TagNumber(3)
   set encryptedGroupState($core.List<$core.int> v) { $_setBytes(2, v); }
-  @$pb.TagNumber(4)
+  @$pb.TagNumber(3)
   $core.bool hasEncryptedGroupState() => $_has(2);
-  @$pb.TagNumber(4)
+  @$pb.TagNumber(3)
-  void clearEncryptedGroupState() => clearField(4);
+  void clearEncryptedGroupState() => clearField(3);
 
-  @$pb.TagNumber(5)
+  @$pb.TagNumber(4)
   $core.List<$core.int> get publicKey => $_getN(3);
-  @$pb.TagNumber(5)
+  @$pb.TagNumber(4)
   set publicKey($core.List<$core.int> v) { $_setBytes(3, v); }
-  @$pb.TagNumber(5)
+  @$pb.TagNumber(4)
   $core.bool hasPublicKey() => $_has(3);
-  @$pb.TagNumber(5)
+  @$pb.TagNumber(4)
-  void clearPublicKey() => clearField(5);
+  void clearPublicKey() => clearField(4);
+}
+
+class AppendGroupState_AppendTBS extends $pb.GeneratedMessage {
+  factory AppendGroupState_AppendTBS({
+    $core.List<$core.int>? encryptedGroupStateAppend,
+    $core.List<$core.int>? publicKey,
+    $core.String? groupId,
+    $core.List<$core.int>? nonce,
+  }) {
+    final $result = create();
+    if (encryptedGroupStateAppend != null) {
+      $result.encryptedGroupStateAppend = encryptedGroupStateAppend;
+    }
+    if (publicKey != null) {
+      $result.publicKey = publicKey;
+    }
+    if (groupId != null) {
+      $result.groupId = groupId;
+    }
+    if (nonce != null) {
+      $result.nonce = nonce;
+    }
+    return $result;
+  }
+  AppendGroupState_AppendTBS._() : super();
+  factory AppendGroupState_AppendTBS.fromBuffer($core.List<$core.int> i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromBuffer(i, r);
+  factory AppendGroupState_AppendTBS.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
+
+  static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'AppendGroupState.AppendTBS', package: const $pb.PackageName(_omitMessageNames ? '' : 'http_requests'), createEmptyInstance: create)
+    ..a<$core.List<$core.int>>(1, _omitFieldNames ? '' : 'encryptedGroupStateAppend', $pb.PbFieldType.OY)
+    ..a<$core.List<$core.int>>(2, _omitFieldNames ? '' : 'publicKey', $pb.PbFieldType.OY)
+    ..aOS(3, _omitFieldNames ? '' : 'groupId')
+    ..a<$core.List<$core.int>>(4, _omitFieldNames ? '' : 'nonce', $pb.PbFieldType.OY)
+    ..hasRequiredFields = false
+  ;
+
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.deepCopy] instead. '
+  'Will be removed in next major version')
+  AppendGroupState_AppendTBS clone() => AppendGroupState_AppendTBS()..mergeFromMessage(this);
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.rebuild] instead. '
+  'Will be removed in next major version')
+  AppendGroupState_AppendTBS copyWith(void Function(AppendGroupState_AppendTBS) updates) => super.copyWith((message) => updates(message as AppendGroupState_AppendTBS)) as AppendGroupState_AppendTBS;
+
+  $pb.BuilderInfo get info_ => _i;
+
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupState_AppendTBS create() => AppendGroupState_AppendTBS._();
+  AppendGroupState_AppendTBS createEmptyInstance() => create();
+  static $pb.PbList<AppendGroupState_AppendTBS> createRepeated() => $pb.PbList<AppendGroupState_AppendTBS>();
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupState_AppendTBS getDefault() => _defaultInstance ??= $pb.GeneratedMessage.$_defaultFor<AppendGroupState_AppendTBS>(create);
+  static AppendGroupState_AppendTBS? _defaultInstance;
+
+  @$pb.TagNumber(1)
+  $core.List<$core.int> get encryptedGroupStateAppend => $_getN(0);
+  @$pb.TagNumber(1)
+  set encryptedGroupStateAppend($core.List<$core.int> v) { $_setBytes(0, v); }
+  @$pb.TagNumber(1)
+  $core.bool hasEncryptedGroupStateAppend() => $_has(0);
+  @$pb.TagNumber(1)
+  void clearEncryptedGroupStateAppend() => clearField(1);
+
+  @$pb.TagNumber(2)
+  $core.List<$core.int> get publicKey => $_getN(1);
+  @$pb.TagNumber(2)
+  set publicKey($core.List<$core.int> v) { $_setBytes(1, v); }
+  @$pb.TagNumber(2)
+  $core.bool hasPublicKey() => $_has(1);
+  @$pb.TagNumber(2)
+  void clearPublicKey() => clearField(2);
+
+  @$pb.TagNumber(3)
+  $core.String get groupId => $_getSZ(2);
+  @$pb.TagNumber(3)
+  set groupId($core.String v) { $_setString(2, v); }
+  @$pb.TagNumber(3)
+  $core.bool hasGroupId() => $_has(2);
+  @$pb.TagNumber(3)
+  void clearGroupId() => clearField(3);
+
+  @$pb.TagNumber(4)
+  $core.List<$core.int> get nonce => $_getN(3);
+  @$pb.TagNumber(4)
+  set nonce($core.List<$core.int> v) { $_setBytes(3, v); }
+  @$pb.TagNumber(4)
+  $core.bool hasNonce() => $_has(3);
+  @$pb.TagNumber(4)
+  void clearNonce() => clearField(4);
+}
+
+class AppendGroupState extends $pb.GeneratedMessage {
+  factory AppendGroupState({
+    $core.List<$core.int>? signature,
+    AppendGroupState_AppendTBS? appendTBS,
+    $fixnum.Int64? versionId,
+  }) {
+    final $result = create();
+    if (signature != null) {
+      $result.signature = signature;
+    }
+    if (appendTBS != null) {
+      $result.appendTBS = appendTBS;
+    }
+    if (versionId != null) {
+      $result.versionId = versionId;
+    }
+    return $result;
+  }
+  AppendGroupState._() : super();
+  factory AppendGroupState.fromBuffer($core.List<$core.int> i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromBuffer(i, r);
+  factory AppendGroupState.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
+
+  static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'AppendGroupState', package: const $pb.PackageName(_omitMessageNames ? '' : 'http_requests'), createEmptyInstance: create)
+    ..a<$core.List<$core.int>>(1, _omitFieldNames ? '' : 'signature', $pb.PbFieldType.OY)
+    ..aOM<AppendGroupState_AppendTBS>(2, _omitFieldNames ? '' : 'appendTBS', protoName: 'appendTBS', subBuilder: AppendGroupState_AppendTBS.create)
+    ..a<$fixnum.Int64>(3, _omitFieldNames ? '' : 'versionId', $pb.PbFieldType.OU6, protoName: 'versionId', defaultOrMaker: $fixnum.Int64.ZERO)
+    ..hasRequiredFields = false
+  ;
+
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.deepCopy] instead. '
+  'Will be removed in next major version')
+  AppendGroupState clone() => AppendGroupState()..mergeFromMessage(this);
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.rebuild] instead. '
+  'Will be removed in next major version')
+  AppendGroupState copyWith(void Function(AppendGroupState) updates) => super.copyWith((message) => updates(message as AppendGroupState)) as AppendGroupState;
+
+  $pb.BuilderInfo get info_ => _i;
+
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupState create() => AppendGroupState._();
+  AppendGroupState createEmptyInstance() => create();
+  static $pb.PbList<AppendGroupState> createRepeated() => $pb.PbList<AppendGroupState>();
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupState getDefault() => _defaultInstance ??= $pb.GeneratedMessage.$_defaultFor<AppendGroupState>(create);
+  static AppendGroupState? _defaultInstance;
+
+  @$pb.TagNumber(1)
+  $core.List<$core.int> get signature => $_getN(0);
+  @$pb.TagNumber(1)
+  set signature($core.List<$core.int> v) { $_setBytes(0, v); }
+  @$pb.TagNumber(1)
+  $core.bool hasSignature() => $_has(0);
+  @$pb.TagNumber(1)
+  void clearSignature() => clearField(1);
+
+  @$pb.TagNumber(2)
+  AppendGroupState_AppendTBS get appendTBS => $_getN(1);
+  @$pb.TagNumber(2)
+  set appendTBS(AppendGroupState_AppendTBS v) { setField(2, v); }
+  @$pb.TagNumber(2)
+  $core.bool hasAppendTBS() => $_has(1);
+  @$pb.TagNumber(2)
+  void clearAppendTBS() => clearField(2);
+  @$pb.TagNumber(2)
+  AppendGroupState_AppendTBS ensureAppendTBS() => $_ensure(1);
+
+  @$pb.TagNumber(3)
+  $fixnum.Int64 get versionId => $_getI64(2);
+  @$pb.TagNumber(3)
+  set versionId($fixnum.Int64 v) { $_setInt64(2, v); }
+  @$pb.TagNumber(3)
+  $core.bool hasVersionId() => $_has(2);
+  @$pb.TagNumber(3)
+  void clearVersionId() => clearField(3);
 }
 
 class GroupState extends $pb.GeneratedMessage {
   factory GroupState({
     $fixnum.Int64? versionId,
     $core.List<$core.int>? encryptedGroupState,
+    $core.Iterable<AppendGroupState>? appendedGroupStates,
   }) {
     final $result = create();
     if (versionId != null) {
@@ -450,6 +623,9 @@ class GroupState extends $pb.GeneratedMessage {
     if (encryptedGroupState != null) {
       $result.encryptedGroupState = encryptedGroupState;
     }
+    if (appendedGroupStates != null) {
+      $result.appendedGroupStates.addAll(appendedGroupStates);
+    }
     return $result;
   }
   GroupState._() : super();
@@ -457,8 +633,9 @@ class GroupState extends $pb.GeneratedMessage {
   factory GroupState.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
 
   static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'GroupState', package: const $pb.PackageName(_omitMessageNames ? '' : 'http_requests'), createEmptyInstance: create)
-    ..a<$fixnum.Int64>(1, _omitFieldNames ? '' : 'versionId', $pb.PbFieldType.OU6, protoName: 'versionId', defaultOrMaker: $fixnum.Int64.ZERO)
+    ..a<$fixnum.Int64>(1, _omitFieldNames ? '' : 'versionId', $pb.PbFieldType.OU6, defaultOrMaker: $fixnum.Int64.ZERO)
-    ..a<$core.List<$core.int>>(3, _omitFieldNames ? '' : 'encryptedGroupState', $pb.PbFieldType.OY)
+    ..a<$core.List<$core.int>>(2, _omitFieldNames ? '' : 'encryptedGroupState', $pb.PbFieldType.OY)
+    ..pc<AppendGroupState>(3, _omitFieldNames ? '' : 'appendedGroupStates', $pb.PbFieldType.PM, subBuilder: AppendGroupState.create)
     ..hasRequiredFields = false
   ;
 
@@ -492,14 +669,62 @@ class GroupState extends $pb.GeneratedMessage {
   @$pb.TagNumber(1)
   void clearVersionId() => clearField(1);
 
-  @$pb.TagNumber(3)
+  @$pb.TagNumber(2)
   $core.List<$core.int> get encryptedGroupState => $_getN(1);
-  @$pb.TagNumber(3)
+  @$pb.TagNumber(2)
   set encryptedGroupState($core.List<$core.int> v) { $_setBytes(1, v); }
-  @$pb.TagNumber(3)
+  @$pb.TagNumber(2)
   $core.bool hasEncryptedGroupState() => $_has(1);
+  @$pb.TagNumber(2)
+  void clearEncryptedGroupState() => clearField(2);
+
   @$pb.TagNumber(3)
-  void clearEncryptedGroupState() => clearField(3);
+  $core.List<AppendGroupState> get appendedGroupStates => $_getList(2);
+}
+
+/// this is just a database helper to store multiple appends
+class AppendGroupStateHelper extends $pb.GeneratedMessage {
+  factory AppendGroupStateHelper({
+    $core.Iterable<AppendGroupState>? appendedGroupStates,
+  }) {
+    final $result = create();
+    if (appendedGroupStates != null) {
+      $result.appendedGroupStates.addAll(appendedGroupStates);
+    }
+    return $result;
+  }
+  AppendGroupStateHelper._() : super();
+  factory AppendGroupStateHelper.fromBuffer($core.List<$core.int> i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromBuffer(i, r);
+  factory AppendGroupStateHelper.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
+
+  static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'AppendGroupStateHelper', package: const $pb.PackageName(_omitMessageNames ? '' : 'http_requests'), createEmptyInstance: create)
+    ..pc<AppendGroupState>(1, _omitFieldNames ? '' : 'appendedGroupStates', $pb.PbFieldType.PM, subBuilder: AppendGroupState.create)
+    ..hasRequiredFields = false
+  ;
+
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.deepCopy] instead. '
+  'Will be removed in next major version')
+  AppendGroupStateHelper clone() => AppendGroupStateHelper()..mergeFromMessage(this);
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.rebuild] instead. '
+  'Will be removed in next major version')
+  AppendGroupStateHelper copyWith(void Function(AppendGroupStateHelper) updates) => super.copyWith((message) => updates(message as AppendGroupStateHelper)) as AppendGroupStateHelper;
+
+  $pb.BuilderInfo get info_ => _i;
+
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupStateHelper create() => AppendGroupStateHelper._();
+  AppendGroupStateHelper createEmptyInstance() => create();
+  static $pb.PbList<AppendGroupStateHelper> createRepeated() => $pb.PbList<AppendGroupStateHelper>();
+  @$core.pragma('dart2js:noInline')
+  static AppendGroupStateHelper getDefault() => _defaultInstance ??= $pb.GeneratedMessage.$_defaultFor<AppendGroupStateHelper>(create);
+  static AppendGroupStateHelper? _defaultInstance;
+
+  @$pb.TagNumber(1)
+  $core.List<AppendGroupState> get appendedGroupStates => $_getList(0);
 }
 
 

lib/src/model/protobuf/api/http/http_requests.pbjson.dart

@@ -89,30 +89,77 @@ final $typed_data.Uint8List updateGroupStateDescriptor = $convert.base64Decode(
 const NewGroupState$json = {
   '1': 'NewGroupState',
   '2': [
-    {'1': 'groupId', '3': 1, '4': 1, '5': 9, '10': 'groupId'},
+    {'1': 'group_id', '3': 1, '4': 1, '5': 9, '10': 'groupId'},
-    {'1': 'versionId', '3': 2, '4': 1, '5': 4, '10': 'versionId'},
+    {'1': 'version_id', '3': 2, '4': 1, '5': 4, '10': 'versionId'},
-    {'1': 'encrypted_group_state', '3': 4, '4': 1, '5': 12, '10': 'encryptedGroupState'},
+    {'1': 'encrypted_group_state', '3': 3, '4': 1, '5': 12, '10': 'encryptedGroupState'},
-    {'1': 'public_key', '3': 5, '4': 1, '5': 12, '10': 'publicKey'},
+    {'1': 'public_key', '3': 4, '4': 1, '5': 12, '10': 'publicKey'},
   ],
 };
 
 /// Descriptor for `NewGroupState`. Decode as a `google.protobuf.DescriptorProto`.
 final $typed_data.Uint8List newGroupStateDescriptor = $convert.base64Decode(
-    'Cg1OZXdHcm91cFN0YXRlEhgKB2dyb3VwSWQYASABKAlSB2dyb3VwSWQSHAoJdmVyc2lvbklkGA'
+    'Cg1OZXdHcm91cFN0YXRlEhkKCGdyb3VwX2lkGAEgASgJUgdncm91cElkEh0KCnZlcnNpb25faW'
-    'IgASgEUgl2ZXJzaW9uSWQSMgoVZW5jcnlwdGVkX2dyb3VwX3N0YXRlGAQgASgMUhNlbmNyeXB0'
+    'QYAiABKARSCXZlcnNpb25JZBIyChVlbmNyeXB0ZWRfZ3JvdXBfc3RhdGUYAyABKAxSE2VuY3J5'
-    'ZWRHcm91cFN0YXRlEh0KCnB1YmxpY19rZXkYBSABKAxSCXB1YmxpY0tleQ==');
+    'cHRlZEdyb3VwU3RhdGUSHQoKcHVibGljX2tleRgEIAEoDFIJcHVibGljS2V5');
+
+@$core.Deprecated('Use appendGroupStateDescriptor instead')
+const AppendGroupState$json = {
+  '1': 'AppendGroupState',
+  '2': [
+    {'1': 'signature', '3': 1, '4': 1, '5': 12, '10': 'signature'},
+    {'1': 'appendTBS', '3': 2, '4': 1, '5': 11, '6': '.http_requests.AppendGroupState.AppendTBS', '10': 'appendTBS'},
+    {'1': 'versionId', '3': 3, '4': 1, '5': 4, '10': 'versionId'},
+  ],
+  '3': [AppendGroupState_AppendTBS$json],
+};
+
+@$core.Deprecated('Use appendGroupStateDescriptor instead')
+const AppendGroupState_AppendTBS$json = {
+  '1': 'AppendTBS',
+  '2': [
+    {'1': 'encrypted_group_state_append', '3': 1, '4': 1, '5': 12, '10': 'encryptedGroupStateAppend'},
+    {'1': 'public_key', '3': 2, '4': 1, '5': 12, '10': 'publicKey'},
+    {'1': 'group_id', '3': 3, '4': 1, '5': 9, '10': 'groupId'},
+    {'1': 'nonce', '3': 4, '4': 1, '5': 12, '10': 'nonce'},
+  ],
+};
+
+/// Descriptor for `AppendGroupState`. Decode as a `google.protobuf.DescriptorProto`.
+final $typed_data.Uint8List appendGroupStateDescriptor = $convert.base64Decode(
+    'ChBBcHBlbmRHcm91cFN0YXRlEhwKCXNpZ25hdHVyZRgBIAEoDFIJc2lnbmF0dXJlEkcKCWFwcG'
+    'VuZFRCUxgCIAEoCzIpLmh0dHBfcmVxdWVzdHMuQXBwZW5kR3JvdXBTdGF0ZS5BcHBlbmRUQlNS'
+    'CWFwcGVuZFRCUxIcCgl2ZXJzaW9uSWQYAyABKARSCXZlcnNpb25JZBqcAQoJQXBwZW5kVEJTEj'
+    '8KHGVuY3J5cHRlZF9ncm91cF9zdGF0ZV9hcHBlbmQYASABKAxSGWVuY3J5cHRlZEdyb3VwU3Rh'
+    'dGVBcHBlbmQSHQoKcHVibGljX2tleRgCIAEoDFIJcHVibGljS2V5EhkKCGdyb3VwX2lkGAMgAS'
+    'gJUgdncm91cElkEhQKBW5vbmNlGAQgASgMUgVub25jZQ==');
 
 @$core.Deprecated('Use groupStateDescriptor instead')
 const GroupState$json = {
   '1': 'GroupState',
   '2': [
-    {'1': 'versionId', '3': 1, '4': 1, '5': 4, '10': 'versionId'},
+    {'1': 'version_id', '3': 1, '4': 1, '5': 4, '10': 'versionId'},
-    {'1': 'encrypted_group_state', '3': 3, '4': 1, '5': 12, '10': 'encryptedGroupState'},
+    {'1': 'encrypted_group_state', '3': 2, '4': 1, '5': 12, '10': 'encryptedGroupState'},
+    {'1': 'appended_group_states', '3': 3, '4': 3, '5': 11, '6': '.http_requests.AppendGroupState', '10': 'appendedGroupStates'},
   ],
 };
 
 /// Descriptor for `GroupState`. Decode as a `google.protobuf.DescriptorProto`.
 final $typed_data.Uint8List groupStateDescriptor = $convert.base64Decode(
-    'CgpHcm91cFN0YXRlEhwKCXZlcnNpb25JZBgBIAEoBFIJdmVyc2lvbklkEjIKFWVuY3J5cHRlZF'
+    'CgpHcm91cFN0YXRlEh0KCnZlcnNpb25faWQYASABKARSCXZlcnNpb25JZBIyChVlbmNyeXB0ZW'
-    '9ncm91cF9zdGF0ZRgDIAEoDFITZW5jcnlwdGVkR3JvdXBTdGF0ZQ==');
+    'RfZ3JvdXBfc3RhdGUYAiABKAxSE2VuY3J5cHRlZEdyb3VwU3RhdGUSUwoVYXBwZW5kZWRfZ3Jv'
+    'dXBfc3RhdGVzGAMgAygLMh8uaHR0cF9yZXF1ZXN0cy5BcHBlbmRHcm91cFN0YXRlUhNhcHBlbm'
+    'RlZEdyb3VwU3RhdGVz');
+
+@$core.Deprecated('Use appendGroupStateHelperDescriptor instead')
+const AppendGroupStateHelper$json = {
+  '1': 'AppendGroupStateHelper',
+  '2': [
+    {'1': 'appended_group_states', '3': 1, '4': 3, '5': 11, '6': '.http_requests.AppendGroupState', '10': 'appendedGroupStates'},
+  ],
+};
+
+/// Descriptor for `AppendGroupStateHelper`. Decode as a `google.protobuf.DescriptorProto`.
+final $typed_data.Uint8List appendGroupStateHelperDescriptor = $convert.base64Decode(
+    'ChZBcHBlbmRHcm91cFN0YXRlSGVscGVyElMKFWFwcGVuZGVkX2dyb3VwX3N0YXRlcxgBIAMoCz'
+    'IfLmh0dHBfcmVxdWVzdHMuQXBwZW5kR3JvdXBTdGF0ZVITYXBwZW5kZWRHcm91cFN0YXRlcw==');
 

lib/src/model/protobuf/client/generated/groups.pb.dart

@@ -14,6 +14,10 @@ import 'dart:core' as $core;
 import 'package:fixnum/fixnum.dart' as $fixnum;
 import 'package:protobuf/protobuf.dart' as $pb;
 
+import 'groups.pbenum.dart';
+
+export 'groups.pbenum.dart';
+
 /// Stored encrypted on the server in the members columns.
 class EncryptedGroupState extends $pb.GeneratedMessage {
   factory EncryptedGroupState({
@@ -109,6 +113,56 @@ class EncryptedGroupState extends $pb.GeneratedMessage {
   void clearPadding() => clearField(5);
 }
 
+class EncryptedAppendedGroupState extends $pb.GeneratedMessage {
+  factory EncryptedAppendedGroupState({
+    EncryptedAppendedGroupState_Type? type,
+  }) {
+    final $result = create();
+    if (type != null) {
+      $result.type = type;
+    }
+    return $result;
+  }
+  EncryptedAppendedGroupState._() : super();
+  factory EncryptedAppendedGroupState.fromBuffer($core.List<$core.int> i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromBuffer(i, r);
+  factory EncryptedAppendedGroupState.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);
+
+  static final $pb.BuilderInfo _i = $pb.BuilderInfo(_omitMessageNames ? '' : 'EncryptedAppendedGroupState', createEmptyInstance: create)
+    ..e<EncryptedAppendedGroupState_Type>(1, _omitFieldNames ? '' : 'type', $pb.PbFieldType.OE, defaultOrMaker: EncryptedAppendedGroupState_Type.LEFT_GROUP, valueOf: EncryptedAppendedGroupState_Type.valueOf, enumValues: EncryptedAppendedGroupState_Type.values)
+    ..hasRequiredFields = false
+  ;
+
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.deepCopy] instead. '
+  'Will be removed in next major version')
+  EncryptedAppendedGroupState clone() => EncryptedAppendedGroupState()..mergeFromMessage(this);
+  @$core.Deprecated(
+  'Using this can add significant overhead to your binary. '
+  'Use [GeneratedMessageGenericExtensions.rebuild] instead. '
+  'Will be removed in next major version')
+  EncryptedAppendedGroupState copyWith(void Function(EncryptedAppendedGroupState) updates) => super.copyWith((message) => updates(message as EncryptedAppendedGroupState)) as EncryptedAppendedGroupState;
+
+  $pb.BuilderInfo get info_ => _i;
+
+  @$core.pragma('dart2js:noInline')
+  static EncryptedAppendedGroupState create() => EncryptedAppendedGroupState._();
+  EncryptedAppendedGroupState createEmptyInstance() => create();
+  static $pb.PbList<EncryptedAppendedGroupState> createRepeated() => $pb.PbList<EncryptedAppendedGroupState>();
+  @$core.pragma('dart2js:noInline')
+  static EncryptedAppendedGroupState getDefault() => _defaultInstance ??= $pb.GeneratedMessage.$_defaultFor<EncryptedAppendedGroupState>(create);
+  static EncryptedAppendedGroupState? _defaultInstance;
+
+  @$pb.TagNumber(1)
+  EncryptedAppendedGroupState_Type get type => $_getN(0);
+  @$pb.TagNumber(1)
+  set type(EncryptedAppendedGroupState_Type v) { setField(1, v); }
+  @$pb.TagNumber(1)
+  $core.bool hasType() => $_has(0);
+  @$pb.TagNumber(1)
+  void clearType() => clearField(1);
+}
+
 class EncryptedGroupStateEnvelop extends $pb.GeneratedMessage {
   factory EncryptedGroupStateEnvelop({
     $core.List<$core.int>? nonce,

lib/src/model/protobuf/client/generated/groups.pbenum.dart

@@ -9,3 +9,22 @@
 // ignore_for_file: non_constant_identifier_names, prefer_final_fields
 // ignore_for_file: unnecessary_import, unnecessary_this, unused_import
 
+import 'dart:core' as $core;
+
+import 'package:protobuf/protobuf.dart' as $pb;
+
+class EncryptedAppendedGroupState_Type extends $pb.ProtobufEnum {
+  static const EncryptedAppendedGroupState_Type LEFT_GROUP = EncryptedAppendedGroupState_Type._(0, _omitEnumNames ? '' : 'LEFT_GROUP');
+
+  static const $core.List<EncryptedAppendedGroupState_Type> values = <EncryptedAppendedGroupState_Type> [
+    LEFT_GROUP,
+  ];
+
+  static final $core.Map<$core.int, EncryptedAppendedGroupState_Type> _byValue = $pb.ProtobufEnum.initByValue(values);
+  static EncryptedAppendedGroupState_Type? valueOf($core.int value) => _byValue[value];
+
+  const EncryptedAppendedGroupState_Type._($core.int v, $core.String n) : super(v, n);
+}
+
+
+const _omitEnumNames = $core.bool.fromEnvironment('protobuf.omit_enum_names');

lib/src/model/protobuf/client/generated/groups.pbjson.dart

@@ -36,6 +36,28 @@ final $typed_data.Uint8List encryptedGroupStateDescriptor = $convert.base64Decod
     'VzQWZ0ZXJNaWxsaXNlY29uZHOIAQESGAoHcGFkZGluZxgFIAEoDFIHcGFkZGluZ0IiCiBfZGVs'
     'ZXRlTWVzc2FnZXNBZnRlck1pbGxpc2Vjb25kcw==');
 
+@$core.Deprecated('Use encryptedAppendedGroupStateDescriptor instead')
+const EncryptedAppendedGroupState$json = {
+  '1': 'EncryptedAppendedGroupState',
+  '2': [
+    {'1': 'type', '3': 1, '4': 1, '5': 14, '6': '.EncryptedAppendedGroupState.Type', '10': 'type'},
+  ],
+  '4': [EncryptedAppendedGroupState_Type$json],
+};
+
+@$core.Deprecated('Use encryptedAppendedGroupStateDescriptor instead')
+const EncryptedAppendedGroupState_Type$json = {
+  '1': 'Type',
+  '2': [
+    {'1': 'LEFT_GROUP', '2': 0},
+  ],
+};
+
+/// Descriptor for `EncryptedAppendedGroupState`. Decode as a `google.protobuf.DescriptorProto`.
+final $typed_data.Uint8List encryptedAppendedGroupStateDescriptor = $convert.base64Decode(
+    'ChtFbmNyeXB0ZWRBcHBlbmRlZEdyb3VwU3RhdGUSNQoEdHlwZRgBIAEoDjIhLkVuY3J5cHRlZE'
+    'FwcGVuZGVkR3JvdXBTdGF0ZS5UeXBlUgR0eXBlIhYKBFR5cGUSDgoKTEVGVF9HUk9VUBAA');
+
 @$core.Deprecated('Use encryptedGroupStateEnvelopDescriptor instead')
 const EncryptedGroupStateEnvelop$json = {
   '1': 'EncryptedGroupStateEnvelop',

lib/src/model/protobuf/client/groups.proto

@@ -9,6 +9,13 @@ message EncryptedGroupState {
     bytes padding = 5;
 }
 
+message EncryptedAppendedGroupState {
+    enum Type {
+        LEFT_GROUP = 0;
+    }
+    Type type = 1;
+}
+
 message EncryptedGroupStateEnvelop {
     bytes nonce = 1;
     bytes encryptedGroupState = 2;

lib/src/services/api/client2client/groups.c2c.dart

@@ -57,6 +57,7 @@ Future<void> handleGroupCreate(
         groupName: const Value(''),
         joinedGroup: const Value(false),
         leftGroup: const Value(false),
+        deletedContent: const Value(false),
       ),
     );
   }

lib/src/services/group.services.dart

@@ -1,12 +1,12 @@
 import 'dart:async';
 import 'dart:convert';
 import 'dart:math';
-import 'dart:typed_data';
 import 'package:collection/collection.dart';
 import 'package:cryptography_flutter_plus/cryptography_flutter_plus.dart';
 import 'package:cryptography_plus/cryptography_plus.dart';
 import 'package:drift/drift.dart' show Value;
 import 'package:fixnum/fixnum.dart';
+import 'package:flutter/foundation.dart';
 import 'package:hashlib/random.dart';
 import 'package:http/http.dart' as http;
 import 'package:libsignal_protocol_dart/libsignal_protocol_dart.dart';
@@ -170,32 +170,13 @@ Future<void> fetchMissingGroupPublicKey() async {
   }
 }
 
-Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
+Future<List<int>?> _decryptEnvelop(
-  if (group.leftGroup) {
+  Group group,
-    Log.error(
+  List<int> encryptedGroupState,
-      'Could not refresh group state, as user is no longer part of the group',
+) async {
-    );
-    return null;
-  }
   try {
-    var isSuccess = true;
-
-    final response = await http
-        .get(
-          Uri.parse('${getGroupStateUrl()}/${group.groupId}'),
-        )
-        .timeout(const Duration(seconds: 10));
-
-    if (response.statusCode != 200) {
-      Log.error(
-        'Could not load group state. Got status code ${response.statusCode} from server.',
-      );
-      return null;
-    }
-
-    final groupStateServer = GroupState.fromBuffer(response.bodyBytes);
     final envelope = EncryptedGroupStateEnvelop.fromBuffer(
-      groupStateServer.encryptedGroupState,
+      encryptedGroupState,
     );
     final chacha20 = FlutterChacha20.poly1305Aead();
 
@@ -210,19 +191,111 @@ Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
       secretKey: SecretKey(group.stateEncryptionKey!),
     );
 
+    return encryptedGroupStateRaw;
+  } catch (e) {
+    Log.error(e);
+    return null;
+  }
+}
+
+Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
+  try {
+    var isSuccess = true;
+
+    final response = await http
+        .get(
+          Uri.parse('${getGroupStateUrl()}/${group.groupId}'),
+        )
+        .timeout(const Duration(seconds: 10));
+
+    if (response.statusCode != 200) {
+      if (response.statusCode == 404) {
+        // group does not exists any more.
+        await twonlyDB.groupsDao.updateGroup(
+          group.groupId,
+          const GroupsCompanion(
+            leftGroup: Value(true),
+          ),
+        );
+      }
+      Log.error(
+        'Could not load group state. Got status code ${response.statusCode} from server.',
+      );
+      return null;
+    }
+
+    final groupStateServer = GroupState.fromBuffer(response.bodyBytes);
+
+    final encryptedStateRaw =
+        await _decryptEnvelop(group, groupStateServer.encryptedGroupState);
+    if (encryptedStateRaw == null) return null;
+
     final encryptedGroupState =
-        EncryptedGroupState.fromBuffer(encryptedGroupStateRaw);
+        EncryptedGroupState.fromBuffer(encryptedStateRaw);
 
     if (group.stateVersionId >= groupStateServer.versionId.toInt()) {
       Log.info(
         'Group ${group.groupId} has already newest group state from the server!',
       );
-      // return (groupStateServer.versionId.toInt(), encryptedGroupState);
     }
 
-    if (!encryptedGroupState.memberIds.contains(Int64(gUser.userId))) {
+    final memberIds = List<Int64>.from(encryptedGroupState.memberIds);
+    final adminIds = List<Int64>.from(encryptedGroupState.adminIds);
+
+    for (final appendedState in groupStateServer.appendedGroupStates) {
+      final identityKey = IdentityKey.fromBytes(
+        Uint8List.fromList(appendedState.appendTBS.publicKey),
+        0,
+      );
+
+      final valid = Curve.verifySignature(
+        identityKey.publicKey,
+        appendedState.appendTBS.writeToBuffer(),
+        Uint8List.fromList(appendedState.signature),
+      );
+
+      if (!valid) {
+        Log.error('Invalid signature for the appendedState');
+        continue;
+      }
+
+      final encryptedStateRaw = await _decryptEnvelop(
+        group,
+        appendedState.appendTBS.encryptedGroupStateAppend,
+      );
+      if (encryptedStateRaw == null) continue;
+
+      final appended =
+          EncryptedAppendedGroupState.fromBuffer(encryptedStateRaw);
+      if (appended.type == EncryptedAppendedGroupState_Type.LEFT_GROUP) {
+        final keyPair =
+            IdentityKeyPair.fromSerialized(group.myGroupPrivateKey!);
+
+        final appendedPubKey = appendedState.appendTBS.publicKey;
+        final myPubKey = keyPair.getPublicKey().serialize().toList();
+
+        if (listEquals(appendedPubKey, myPubKey)) {
+          adminIds.remove(Int64(gUser.userId));
+          memberIds
+              .remove(Int64(gUser.userId)); // -> Will remove the user later...
+        } else {
+          Log.info('A non admin left the group!!!');
+
+          final member = await twonlyDB.groupsDao
+              .getGroupMemberByPublicKey(Uint8List.fromList(appendedPubKey));
+          if (member == null) {
+            Log.error('Member is already not in this group...');
+            continue;
+          }
+          adminIds.remove(Int64(member.contactId));
+          memberIds.remove(Int64(member.contactId));
+        }
+      }
+    }
+
+    if (!memberIds.contains(Int64(gUser.userId))) {
       // OH no, I am no longer a member of this group...
-      // ->
+      // Return from the group...
       await twonlyDB.groupsDao.updateGroup(
         group.groupId,
         const GroupsCompanion(
@@ -232,9 +305,41 @@ Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
       return (groupStateServer.versionId.toInt(), encryptedGroupState);
     }
 
-    final isGroupAdmin = encryptedGroupState.adminIds
+    final isGroupAdmin =
-            .firstWhereOrNull((t) => t.toInt() == gUser.userId) !=
+        adminIds.firstWhereOrNull((t) => t.toInt() == gUser.userId) != null;
-        null;
+
+    if (!listEquals(memberIds, encryptedGroupState.memberIds)) {
+      if (isGroupAdmin) {
+        try {
+          // this removes the appended_group_state from the server and merges the changes into the main group state
+          final newState = EncryptedGroupState(
+            groupName: encryptedGroupState.groupName,
+            deleteMessagesAfterMilliseconds:
+                encryptedGroupState.deleteMessagesAfterMilliseconds,
+            memberIds: memberIds,
+            adminIds: adminIds,
+            padding: List<int>.generate(Random().nextInt(80), (_) => 0),
+          );
+          // send new state to the server
+          if (!await _updateGroupState(
+            group,
+            newState,
+            versionId: groupStateServer.versionId.toInt() + 1,
+          )) {
+            // could not update the group state...
+            Log.error('Update the state to remove the appended state...');
+            return null;
+          }
+          // the state is now updated and the appended_group_state should be removed on the server, so just call this
+          // function again, to sync the local database
+          return fetchGroupState(group);
+        } catch (e) {
+          Log.error(e);
+          return null;
+        }
+      }
+      // in case this is not an admin, just work with the new memberIds and adminIds...
+    }
 
     await twonlyDB.groupsDao.updateGroup(
       group.groupId,
@@ -251,7 +356,7 @@ Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
         await twonlyDB.groupsDao.getGroupMembers(group.groupId);
 
     // First find and insert NEW members
-    for (final memberId in encryptedGroupState.memberIds) {
+    for (final memberId in memberIds) {
       if (memberId == Int64(gUser.userId)) {
         continue;
       }
@@ -313,7 +418,7 @@ Future<(int, EncryptedGroupState)?> fetchGroupState(Group group) async {
 
       MemberState? newMemberState;
 
-      if (encryptedGroupState.adminIds.contains(Int64(member.contactId))) {
+      if (adminIds.contains(Int64(member.contactId))) {
         if (member.memberState == MemberState.normal) {
           // user was promoted
           newMemberState = MemberState.admin;
@@ -376,6 +481,7 @@ Future<bool> _updateGroupState(
   EncryptedGroupState state, {
   Uint8List? addAdmin,
   Uint8List? removeAdmin,
+  int? versionId,
 }) async {
   final chacha20 = FlutterChacha20.poly1305Aead();
   final encryptionNonce = chacha20.newNonce();
@@ -397,26 +503,14 @@ Future<bool> _updateGroupState(
 
     final keyPair = IdentityKeyPair.fromSerialized(group.myGroupPrivateKey!);
 
-    final publicKey = uint8ListToHex(keyPair.getPublicKey().serialize());
+    final nonce = await getNonce(keyPair.getPublicKey().serialize());
-
+    if (nonce == null) return false;
-    final responseNonce = await http
-        .get(
-          Uri.parse('${getGroupChallengeUrl()}/$publicKey'),
-        )
-        .timeout(const Duration(seconds: 10));
-
-    if (responseNonce.statusCode != 200) {
-      Log.error(
-        'Could not load nonce. Got status code ${responseNonce.statusCode} from server.',
-      );
-      return false;
-    }
 
     final updateTBS = UpdateGroupState_UpdateTBS(
-      versionId: Int64(group.stateVersionId + 1),
+      versionId: Int64(versionId ?? group.stateVersionId + 1),
       encryptedGroupState: encryptedGroupState.writeToBuffer(),
       publicKey: keyPair.getPublicKey().serialize(),
-      nonce: responseNonce.bodyBytes,
+      nonce: nonce,
       addAdmin: addAdmin,
       removeAdmin: removeAdmin,
     );
@@ -452,7 +546,7 @@ Future<bool> _updateGroupState(
 
 Future<bool> manageAdminState(
   Group group,
-  GroupMember member,
+  Uint8List groupPublicKey,
   int contactId,
   bool remove,
 ) async {
@@ -469,7 +563,7 @@ Future<bool> manageAdminState(
   if (remove) {
     if (state.adminIds.contains(userId)) {
       state.adminIds.remove(userId);
-      removeAdmin = member.groupPublicKey;
+      removeAdmin = groupPublicKey;
     } else {
       Log.info('User was already removed as admin.');
       return true;
@@ -477,7 +571,7 @@ Future<bool> manageAdminState(
   } else {
     if (!state.adminIds.contains(userId)) {
       state.adminIds.add(userId);
-      addAdmin = member.groupPublicKey;
+      addAdmin = groupPublicKey;
     } else {
       Log.info('User is already admin.');
       return true;
@@ -524,7 +618,7 @@ Future<bool> manageAdminState(
   return (await fetchGroupState(group)) != null;
 }
 
-Future<bool> updateGroupeName(Group group, String groupName) async {
+Future<bool> updateGroupName(Group group, String groupName) async {
   // ensure the latest state is used
   final currentState = await fetchGroupState(group);
   if (currentState == null) return false;
@@ -624,7 +718,7 @@ Future<bool> addNewGroupMembers(
 
 Future<bool> removeMemberFromGroup(
   Group group,
-  GroupMember member,
+  Uint8List groupPublicKey,
   int removeContactId,
 ) async {
   // ensure the latest state is used
@@ -642,16 +736,16 @@ Future<bool> removeMemberFromGroup(
     return true;
   }
   if (adminIdSet.contains(contactId)) {
-    if (member.groupPublicKey == null) {
+    // if (member.groupPublicKey == null) {
-      // If the admin public key is not removed, that the user could potentially still update the group state. So only
+    //   // If the admin public key is not removed, that the user could potentially still update the group state. So only
-      // allow the user removal, if this key is known. It is better the users can not remove the other user, then
+    //   // allow the user removal, if this key is known. It is better the users can not remove the other user, then
-      // the he can but the other user, could still update the group state.
+    //   // the he can but the other user, could still update the group state.
-      Log.error(
+    //   Log.error(
-        'Could not remove user. User is admin, but groupPublicKey is unknown.',
+    //     'Could not remove user. User is admin, but groupPublicKey is unknown.',
-      );
+    //   );
-      return false;
+    //   return false;
-    }
+    // }
-    removeAdmin = member.groupPublicKey;
+    removeAdmin = groupPublicKey;
   }
 
   membersIdSet.remove(contactId);
@@ -684,10 +778,126 @@ Future<bool> removeMemberFromGroup(
     GroupHistoriesCompanion(
       groupId: Value(group.groupId),
       type: const Value(GroupActionType.removedMember),
-      affectedContactId: Value(removeContactId),
+      affectedContactId: Value(
+        removeContactId == gUser.userId ? null : removeContactId,
+      ),
     ),
   );
 
   // Updates the groupMembers table :)
   return (await fetchGroupState(group)) != null;
 }
+
+Future<Uint8List?> getNonce(Uint8List publicKey) async {
+  final publicKeyHex = uint8ListToHex(publicKey);
+
+  final responseNonce = await http
+      .get(
+        Uri.parse('${getGroupChallengeUrl()}/$publicKeyHex'),
+      )
+      .timeout(const Duration(seconds: 10));
+
+  if (responseNonce.statusCode != 200) {
+    Log.error(
+      'Could not load nonce. Got status code ${responseNonce.statusCode} from server.',
+    );
+    return null;
+  }
+  return responseNonce.bodyBytes;
+}
+
+Future<bool> leaveAsNonAdminFromGroup(Group group) async {
+  final currentState = await fetchGroupState(group);
+  if (currentState == null) {
+    Log.error('Could not load current state');
+    return false;
+  }
+
+  final (version, _) = currentState;
+  if (group.stateVersionId != version) {
+    Log.error('Version is not valid. Just retry.');
+    return false;
+  }
+
+  final chacha20 = FlutterChacha20.poly1305Aead();
+  final encryptionNonce = chacha20.newNonce();
+
+  final state = EncryptedAppendedGroupState(
+    type: EncryptedAppendedGroupState_Type.LEFT_GROUP,
+  );
+
+  final secretBox = await chacha20.encrypt(
+    state.writeToBuffer(),
+    secretKey: SecretKey(group.stateEncryptionKey!),
+    nonce: encryptionNonce,
+  );
+
+  final encryptedGroupStateAppend = EncryptedGroupStateEnvelop(
+    nonce: encryptionNonce,
+    encryptedGroupState: secretBox.cipherText,
+    mac: secretBox.mac.bytes,
+  );
+
+  {
+    // Upload the group state, if this fails, the group can not be created.
+
+    final keyPair = IdentityKeyPair.fromSerialized(group.myGroupPrivateKey!);
+
+    final nonce = await getNonce(keyPair.getPublicKey().serialize());
+    if (nonce == null) return false;
+
+    final appendTBS = AppendGroupState_AppendTBS(
+      publicKey: keyPair.getPublicKey().serialize(),
+      encryptedGroupStateAppend: encryptedGroupStateAppend.writeToBuffer(),
+      groupId: group.groupId,
+      nonce: nonce,
+    );
+
+    final random = getRandomUint8List(32);
+    final signature = sign(
+      keyPair.getPrivateKey().serialize(),
+      appendTBS.writeToBuffer(),
+      random,
+    );
+
+    final newGroupState = AppendGroupState(
+      versionId: Int64(group.stateVersionId + 1),
+      appendTBS: appendTBS,
+      signature: signature,
+    );
+
+    final response = await http
+        .post(
+          Uri.parse('${getGroupStateUrl()}/append'),
+          body: newGroupState.writeToBuffer(),
+        )
+        .timeout(const Duration(seconds: 10));
+
+    if (response.statusCode != 200) {
+      Log.error(
+        'Could not patch group state. Got status code ${response.statusCode} from server.',
+      );
+      return false;
+    }
+  }
+  const groupActionType = GroupActionType.leftGroup;
+  await sendCipherTextToGroup(
+    group.groupId,
+    EncryptedContent(
+      groupUpdate: EncryptedContent_GroupUpdate(
+        groupActionType: groupActionType.name,
+        affectedContactId: Int64(gUser.userId),
+      ),
+    ),
+  );
+
+  await twonlyDB.groupsDao.insertGroupAction(
+    GroupHistoriesCompanion(
+      groupId: Value(group.groupId),
+      type: const Value(groupActionType),
+    ),
+  );
+
+  // Updates the table :)
+  return (await fetchGroupState(group)) != null;
+}

lib/src/views/components/better_list_title.dart

@@ -20,7 +20,7 @@ class BetterListTile extends StatelessWidget {
   final String text;
   final Widget? subtitle;
   final Color? color;
-  final VoidCallback onTap;
+  final VoidCallback? onTap;
   final double iconSize;
   final EdgeInsets? padding;
 

lib/src/views/groups/group.view.dart

@@ -1,12 +1,14 @@
 import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:font_awesome_flutter/font_awesome_flutter.dart';
+import 'package:libsignal_protocol_dart/libsignal_protocol_dart.dart';
 import 'package:twonly/globals.dart';
 import 'package:twonly/src/database/daos/contacts.dao.dart';
 import 'package:twonly/src/database/tables/groups.table.dart';
 import 'package:twonly/src/database/twonly.db.dart';
 import 'package:twonly/src/services/group.services.dart';
 import 'package:twonly/src/utils/misc.dart';
+import 'package:twonly/src/views/components/alert_dialog.dart';
 import 'package:twonly/src/views/components/avatar_icon.component.dart';
 import 'package:twonly/src/views/components/better_list_title.dart';
 import 'package:twonly/src/views/components/verified_shield.dart';
@@ -74,7 +76,7 @@ class _GroupViewState extends State<GroupView> {
         newGroupName != null &&
         newGroupName != '' &&
         newGroupName != group.groupName) {
-      if (!await updateGroupeName(group, newGroupName)) {
+      if (!await updateGroupName(group, newGroupName)) {
         if (mounted) {
           showNetworkIssue(context);
         }
@@ -97,6 +99,60 @@ class _GroupViewState extends State<GroupView> {
     }
   }
 
+  Future<void> _leaveGroup() async {
+    final ok = await showAlertDialog(
+      context,
+      context.lang.leaveGroupSureTitle,
+      context.lang.leaveGroupSureBody,
+      customOk: context.lang.leaveGroupSureOkBtn,
+    );
+    if (!ok) return;
+
+    // 1. Check if I am the only admin, while there are still normal members
+    // -> ERROR first select new admin
+
+    if (members.isNotEmpty) {
+      // In case there are other members, check that there is at least one other admin before I leave the group.
+
+      if (group.isGroupAdmin) {
+        if (!members.any((m) => m.$2.memberState == MemberState.admin)) {
+          if (!mounted) return;
+          await showAlertDialog(
+            context,
+            context.lang.leaveGroupSelectOtherAdminTitle,
+            context.lang.leaveGroupSelectOtherAdminBody,
+            customCancel: '',
+          );
+          return;
+        }
+      }
+    }
+
+    late bool success;
+
+    if (group.isGroupAdmin) {
+      // Current user is a admin, to the state can be updated by the user him self.
+      final keyPair = IdentityKeyPair.fromSerialized(group.myGroupPrivateKey!);
+      success = await removeMemberFromGroup(
+        group,
+        keyPair.getPublicKey().serialize(),
+        gUser.userId,
+      );
+    } else {
+      success = await leaveAsNonAdminFromGroup(group);
+    }
+
+    if (!success) {
+      if (mounted) {
+        showNetworkIssue(context);
+        return;
+      }
+    }
+    // If not admin -> append to the server state
+
+    // -> Inform the other users
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -126,7 +182,7 @@ class _GroupViewState extends State<GroupView> {
             ],
           ),
           const SizedBox(height: 50),
-          if (group.isGroupAdmin)
+          if (group.isGroupAdmin && !group.leftGroup)
             BetterListTile(
               icon: FontAwesomeIcons.pencil,
               text: context.lang.groupNameInput,
@@ -145,7 +201,7 @@ class _GroupViewState extends State<GroupView> {
               ),
             ),
           ),
-          if (group.isGroupAdmin)
+          if (group.isGroupAdmin && !group.leftGroup)
             BetterListTile(
               icon: FontAwesomeIcons.plus,
               text: context.lang.addMember,
@@ -197,11 +253,24 @@ class _GroupViewState extends State<GroupView> {
           const SizedBox(height: 10),
           const Divider(),
           const SizedBox(height: 10),
+          if (!group.leftGroup)
             BetterListTile(
               icon: FontAwesomeIcons.rightFromBracket,
               color: Colors.red,
               text: context.lang.leaveGroup,
-            onTap: () => {},
+              onTap: _leaveGroup,
+            )
+          else
+            ListTile(
+              title: Padding(
+                padding: const EdgeInsets.only(left: 17),
+                child: Text(
+                  context.lang.groupYouAreNowLongerAMember,
+                  style: const TextStyle(
+                    fontSize: 14,
+                  ),
+                ),
+              ),
             ),
         ],
       ),
@@ -246,9 +315,9 @@ Future<String?> showGroupNameChangeDialog(
 
 void showNetworkIssue(BuildContext context) {
   ScaffoldMessenger.of(context).showSnackBar(
-    const SnackBar(
+    SnackBar(
-      content: Text('Network issue. Try again later.'),
+      content: Text(context.lang.groupNetworkIssue),
-      duration: Duration(seconds: 3),
+      duration: const Duration(seconds: 3),
     ),
   );
 }

lib/src/views/groups/group_member.context.dart

@@ -37,7 +37,7 @@ class GroupMemberContextMenu extends StatelessWidget {
     if (ok) {
       if (!await manageAdminState(
         group,
-        member,
+        member.groupPublicKey!,
         contact.userId,
         false,
       )) {
@@ -58,7 +58,7 @@ class GroupMemberContextMenu extends StatelessWidget {
     if (ok) {
       if (!await manageAdminState(
         group,
-        member,
+        member.groupPublicKey!,
         contact.userId,
         true,
       )) {
@@ -78,7 +78,7 @@ class GroupMemberContextMenu extends StatelessWidget {
     if (ok) {
       if (!await removeMemberFromGroup(
         group,
-        member,
+        member.groupPublicKey!,
         contact.userId,
       )) {
         if (context.mounted) {
@@ -159,7 +159,7 @@ class GroupMemberContextMenu extends StatelessWidget {
             onTap: () => _removeContactAsAdmin(context),
             icon: FontAwesomeIcons.key,
           ),
-        if (group.isGroupAdmin)
+        if (group.isGroupAdmin && member.groupPublicKey != null)
           ContextMenuItem(
             title: context.lang.removeFromGroup,
             onTap: () => _removeContactFromGroup(context),

test/unit_test.dart

@@ -1,6 +1,9 @@
 import 'dart:typed_data';
+
 import 'package:flutter_test/flutter_test.dart';
 import 'package:hashlib/random.dart';
+import 'package:libsignal_protocol_dart/libsignal_protocol_dart.dart';
+import 'package:libsignal_protocol_dart/src/ecc/ed25519.dart';
 import 'package:twonly/src/utils/misc.dart';
 import 'package:twonly/src/utils/pow.dart';
 import 'package:twonly/src/views/components/animate_icon.dart';
@@ -60,5 +63,20 @@ void main() {
     test('Reject values > 0x7fffffff', () {
       expect(() => getUUIDforDirectChat(0x80000000, 0), throwsArgumentError);
     });
+
+    test('sign and verify', () {
+      final keyPair = generateIdentityKeyPair();
+      final message = Uint8List(10);
+
+      final random = getRandomUint8List(32);
+
+      final signature =
+          sign(keyPair.getPrivateKey().serialize(), message, random);
+
+      expect(
+        verifySig(keyPair.getPublicKey().serialize(), message, signature),
+        true,
+      );
+    });
   });
 }