Add terminateGroup command to terminate a group for everyone

Let a group admin permanently terminate a GroupV2 group via the
TerminateGroupAction (Groups.proto field 28, change epoch 7) the pinned library
already exposes as GroupsV2Operations.createTerminateGroup().

- GroupV2Helper.terminateGroup builds and commits the change
- GroupHelper.terminateGroup resolves/refreshes the group (v2 only), sends the
  update to members and syncs storage, with the same conflict-retry as
  updateGroup
- exposed through Manager.terminateGroup, the terminateGroup CLI/JSON-RPC command
  and the DBus Group.terminateGroup method

lib/src/main/java/org/asamk/signal/manager/Manager.java

@@ -184,6 +184,10 @@ public interface Manager extends Closeable {
 
     void deleteGroup(GroupId groupId) throws IOException;
 
+    SendGroupMessageResults terminateGroup(
+            GroupId groupId
+    ) throws IOException, GroupNotFoundException, NotAGroupMemberException;
+
     Pair<GroupId, SendGroupMessageResults> createGroup(
             String name,
             Set<RecipientIdentifier.Single> members,

lib/src/main/java/org/asamk/signal/manager/helper/GroupHelper.java

@@ -363,6 +363,28 @@ public class GroupHelper {
         return results;
     }
 
+    public SendGroupMessageResults terminateGroup(final GroupId groupId) throws IOException, GroupNotFoundException, NotAGroupMemberException {
+        final var group = getGroupForUpdating(groupId);
+        if (!(group instanceof GroupInfoV2)) {
+            throw new IOException("Terminating a group is only supported for Signal group v2 groups.");
+        }
+
+        SendGroupMessageResults results;
+        try {
+            results = terminateGroupV2((GroupInfoV2) group);
+        } catch (ConflictException e) {
+            // Detected conflicting update, refreshing group and trying again
+            results = terminateGroupV2((GroupInfoV2) getGroup(groupId, true));
+        }
+        context.getJobExecutor().enqueueJob(new SyncStorageJob());
+        return results;
+    }
+
+    private SendGroupMessageResults terminateGroupV2(final GroupInfoV2 group) throws IOException {
+        final var groupGroupChangePair = context.getGroupV2Helper().terminateGroup(group);
+        return sendUpdateGroupV2Message(group, groupGroupChangePair.first(), groupGroupChangePair.second());
+    }
+
     public void updateGroupProfileKey(GroupIdV2 groupId) throws GroupNotFoundException, NotAGroupMemberException, IOException {
         var group = getGroupForUpdating(groupId);
 

lib/src/main/java/org/asamk/signal/manager/helper/GroupV2Helper.java

@@ -543,6 +543,14 @@ class GroupV2Helper {
         return commitChange(groupInfoV2, change);
     }
 
+    Pair<DecryptedGroup, GroupChangeResponse> terminateGroup(
+            GroupInfoV2 groupInfoV2
+    ) throws IOException {
+        final GroupsV2Operations.GroupOperations groupOperations = getGroupOperations(groupInfoV2);
+        final var change = groupOperations.createTerminateGroup();
+        return commitChange(groupInfoV2, change);
+    }
+
     Pair<DecryptedGroup, GroupChangeResponse> setMemberLabels(
             GroupInfoV2 groupInfoV2,
             String labelEmoji,

lib/src/main/java/org/asamk/signal/manager/internal/ManagerImpl.java

@@ -610,6 +610,11 @@ public class ManagerImpl implements Manager {
         context.getGroupHelper().deleteGroup(groupId);
     }
 
+    @Override
+    public SendGroupMessageResults terminateGroup(GroupId groupId) throws IOException, GroupNotFoundException, NotAGroupMemberException {
+        return context.getGroupHelper().terminateGroup(groupId);
+    }
+
     @Override
     public Pair<GroupId, SendGroupMessageResults> createGroup(
             String name,

man/signal-cli-dbus.5.adoc

@@ -503,6 +503,11 @@ Exceptions: Failure
 quitGroup() -> <>::
 Exceptions: Failure, LastGroupAdmin
 
+terminateGroup() -> <>::
+Permanently terminate the group for all members (requires admin privileges). Afterwards nobody can send messages or start calls; members keep access to the existing history.
+
+Exceptions: Failure
+
 removeAdmins(recipients<as>) -> <>::
 * recipients : String array of phone numbers
 

man/signal-cli.1.adoc

@@ -786,6 +786,16 @@ Specify the recipient group ID in base64 encoding.
 *--delete*::
 Delete local group data completely after quitting group.
 
+=== terminateGroup
+
+Permanently terminate a group for all members.
+This requires admin privileges.
+Afterwards no member (not even an admin) can send messages or start calls in the group; members keep access to the existing message history.
+Only supported for Signal group v2 groups.
+
+*-g* GROUP, *--group-id* GROUP::
+Specify the group ID in base64 encoding.
+
 === listGroups
 
 Show a list of known groups and related information.

src/main/java/org/asamk/Signal.java

@@ -612,6 +612,8 @@ public interface Signal extends DBusInterface {
 
         void deleteGroup() throws Error.Failure;
 
+        void terminateGroup() throws Error.Failure;
+
         void addMembers(List<String> recipients) throws Error.Failure;
 
         void removeMembers(List<String> recipients) throws Error.Failure;

src/main/java/org/asamk/signal/commands/Commands.java

@@ -61,6 +61,7 @@ public class Commands {
         addCommand(new SubmitRateLimitChallengeCommand());
         addCommand(new StartChangeNumberCommand());
         addCommand(new StartLinkCommand());
+        addCommand(new TerminateGroupCommand());
         addCommand(new TrustCommand());
         addCommand(new UnblockCommand());
         addCommand(new UnregisterCommand());

src/main/java/org/asamk/signal/commands/TerminateGroupCommand.java

@@ -0,0 +1,54 @@
+package org.asamk.signal.commands;
+
+import net.sourceforge.argparse4j.inf.Namespace;
+import net.sourceforge.argparse4j.inf.Subparser;
+
+import org.asamk.signal.commands.exceptions.CommandException;
+import org.asamk.signal.commands.exceptions.IOErrorException;
+import org.asamk.signal.commands.exceptions.UserErrorException;
+import org.asamk.signal.manager.Manager;
+import org.asamk.signal.manager.api.GroupNotFoundException;
+import org.asamk.signal.manager.api.NotAGroupMemberException;
+import org.asamk.signal.output.OutputWriter;
+import org.asamk.signal.util.CommandUtil;
+
+import java.io.IOException;
+
+import static org.asamk.signal.util.SendMessageResultUtils.outputResult;
+
+public class TerminateGroupCommand implements JsonRpcLocalCommand {
+
+    @Override
+    public String getName() {
+        return "terminateGroup";
+    }
+
+    @Override
+    public void attachToSubparser(final Subparser subparser) {
+        subparser.help(
+                "Permanently terminate a group for all members. Requires admin privileges; afterwards nobody can send messages or start calls.");
+        subparser.addArgument("-g", "--group-id", "--group").required(true).help("Specify the group ID.");
+    }
+
+    @Override
+    public void handleCommand(
+            final Namespace ns,
+            final Manager m,
+            final OutputWriter outputWriter
+    ) throws CommandException {
+        final var groupId = CommandUtil.getGroupId(ns.getString("group-id"));
+
+        try {
+            final var results = m.terminateGroup(groupId);
+            outputResult(outputWriter, results);
+        } catch (IOException e) {
+            throw new IOErrorException("Failed to send message: "
+                    + e.getMessage()
+                    + " ("
+                    + e.getClass().getSimpleName()
+                    + ")", e);
+        } catch (GroupNotFoundException | NotAGroupMemberException e) {
+            throw new UserErrorException("Failed to terminate group: " + e.getMessage());
+        }
+    }
+}

src/main/java/org/asamk/signal/dbus/DbusManagerImpl.java

@@ -327,6 +327,21 @@ public class DbusManagerImpl implements Manager {
         group.deleteGroup();
     }
 
+    @Override
+    public SendGroupMessageResults terminateGroup(
+            final GroupId groupId
+    ) throws IOException, GroupNotFoundException, NotAGroupMemberException {
+        final var group = getRemoteObject(signal.getGroup(groupId.serialize()), Signal.Group.class);
+        try {
+            group.terminateGroup();
+        } catch (Signal.Error.GroupNotFound e) {
+            throw new GroupNotFoundException(groupId);
+        } catch (Signal.Error.NotAGroupMember e) {
+            throw new NotAGroupMemberException(groupId, group.Get("org.asamk.Signal.Group", "Name"));
+        }
+        return new SendGroupMessageResults(0, List.of());
+    }
+
     @Override
     public Pair<GroupId, SendGroupMessageResults> createGroup(
             final String name,

src/main/java/org/asamk/signal/dbus/DbusSignalImpl.java

@@ -1376,6 +1376,19 @@ public class DbusSignalImpl implements Signal, AutoCloseable {
             updateGroups();
         }
 
+        @Override
+        public void terminateGroup() throws Error.Failure {
+            try {
+                m.terminateGroup(groupId);
+            } catch (GroupNotFoundException e) {
+                throw new Error.GroupNotFound(e.getMessage());
+            } catch (NotAGroupMemberException e) {
+                throw new Error.NotAGroupMember(e.getMessage());
+            } catch (IOException e) {
+                throw new Error.Failure(e.getMessage());
+            }
+        }
+
         @Override
         public void addMembers(final List<String> recipients) throws Error.Failure {
             final var memberIdentifiers = getSingleRecipientIdentifiers(recipients, m.getSelfNumber());