Prevent last admin from leaving without selecting new admin.

app/src/main/AndroidManifest.xml

@@ -504,6 +504,9 @@
     <activity android:name=".groups.ui.creategroup.details.AddGroupDetailsActivity"
               android:theme="@style/Theme.Signal.DayNight.NoActionBar" />
 
+    <activity android:name=".groups.ui.chooseadmin.ChooseNewAdminActivity"
+              android:configChanges="touchscreen|keyboard|keyboardHidden|orientation|screenLayout|screenSize" />
+
     <service android:enabled="true" android:name="org.thoughtcrime.securesms.service.WebRtcCallService"/>
     <service android:enabled="true" android:name=".service.ApplicationMigrationService"/>
     <service android:enabled="true" android:exported="false" android:name=".service.KeyCachingService"/>

app/src/main/java/org/thoughtcrime/securesms/conversation/ConversationActivity.java

@@ -1203,10 +1203,7 @@ public class ConversationActivity extends PassphraseRequiredActivity
       return;
     }
 
-    LeaveGroupDialog.handleLeavePushGroup(ConversationActivity.this,
+    LeaveGroupDialog.handleLeavePushGroup(this, getRecipient().requireGroupId().requirePush(), this::finish);
-                                          getLifecycle(),
-                                          getRecipient().requireGroupId().requirePush(),
-                                          null);
   }
 
   private void handleManageGroup() {

app/src/main/java/org/thoughtcrime/securesms/groups/GroupManager.java

@@ -139,6 +139,16 @@ public final class GroupManager {
     }
   }
 
+  @WorkerThread
+  public static void addMemberAdminsAndLeaveGroup(@NonNull Context context, @NonNull GroupId.V2 groupId, @NonNull Collection<RecipientId> newAdmins)
+      throws GroupChangeBusyException, GroupChangeFailedException, IOException, GroupInsufficientRightsException, GroupNotAMemberException
+  {
+    try (GroupManagerV2.GroupEditor edit = new GroupManagerV2(context).edit(groupId.requireV2())) {
+      edit.addMemberAdminsAndLeaveGroup(newAdmins);
+      Log.i(TAG, "Left group " + groupId);
+    }
+  }
+
   @WorkerThread
   public static void ejectFromGroup(@NonNull Context context, @NonNull GroupId.V2 groupId, @NonNull Recipient recipient)
       throws GroupChangeBusyException, GroupChangeFailedException, GroupInsufficientRightsException, GroupNotAMemberException, IOException

app/src/main/java/org/thoughtcrime/securesms/groups/GroupManagerV2.java

@@ -6,6 +6,7 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.WorkerThread;
 
+import com.annimon.stream.Stream;
 import com.google.protobuf.InvalidProtocolBufferException;
 
 import org.signal.storageservice.protos.groups.AccessControl;
@@ -296,6 +297,17 @@ final class GroupManagerV2 {
       return commitChangeWithConflictResolution(groupOperations.createRemoveMembersChange(Collections.singleton(recipient.getUuid().get())));
     }
 
+    @WorkerThread
+    @NonNull GroupManager.GroupActionResult addMemberAdminsAndLeaveGroup(Collection<RecipientId> newAdmins)
+        throws GroupChangeFailedException, GroupNotAMemberException, GroupInsufficientRightsException, IOException
+    {
+      Recipient  self               = Recipient.self();
+      List<UUID> newAdminRecipients = Stream.of(newAdmins).map(id -> Recipient.resolved(id).getUuid().get()).toList();
+
+      return commitChangeWithConflictResolution(groupOperations.createLeaveAndPromoteMembersToAdmin(self.getUuid().get(),
+                                                                                                    newAdminRecipients));
+    }
+
     @WorkerThread
     @Nullable GroupManager.GroupActionResult updateSelfProfileKeyInGroup()
         throws GroupChangeFailedException, GroupInsufficientRightsException, IOException, GroupNotAMemberException

app/src/main/java/org/thoughtcrime/securesms/groups/LiveGroup.java

@@ -40,6 +40,7 @@ public final class LiveGroup {
   private final GroupDatabase                               groupDatabase;
   private final LiveData<Recipient>                         recipient;
   private final LiveData<GroupDatabase.GroupRecord>         groupRecord;
+  private final LiveData<List<GroupMemberEntry.FullMember>> fullMembers;
 
   public LiveGroup(@NonNull GroupId groupId) {
     Context                        context       = ApplicationDependencies.getApplication();
@@ -47,7 +48,15 @@ public final class LiveGroup {
 
     this.groupDatabase = DatabaseFactory.getGroupDatabase(context);
     this.recipient     = Transformations.switchMap(liveRecipient, LiveRecipient::getLiveData);
-    this.groupRecord   = LiveDataUtil.filterNotNull(LiveDataUtil.mapAsync(recipient, groupRecipient-> groupDatabase.getGroup(groupRecipient.getId()).orNull()));
+    this.groupRecord   = LiveDataUtil.filterNotNull(LiveDataUtil.mapAsync(recipient, groupRecipient -> groupDatabase.getGroup(groupRecipient.getId()).orNull()));
+    this.fullMembers   = LiveDataUtil.mapAsync(groupRecord,
+                                               g -> Stream.of(g.getMembers())
+                                                          .map(m -> {
+                                                            Recipient recipient = Recipient.resolved(m);
+                                                            return new GroupMemberEntry.FullMember(recipient, g.isAdmin(recipient));
+                                                          })
+                                                          .sorted(MEMBER_ORDER)
+                                                          .toList());
 
     SignalExecutors.BOUNDED.execute(() -> liveRecipient.postValue(Recipient.externalGroup(context, groupId).live()));
   }
@@ -90,17 +99,17 @@ public final class LiveGroup {
     return Transformations.map(groupRecord, GroupDatabase.GroupRecord::getAttributesAccessControl);
   }
 
-  public LiveData<List<GroupMemberEntry.FullMember>> getFullMembers() {
+  public LiveData<List<GroupMemberEntry.FullMember>> getNonAdminFullMembers() {
-    return LiveDataUtil.mapAsync(groupRecord,
+    return Transformations.map(fullMembers,
-                                 g -> Stream.of(g.getMembers())
+                               members -> Stream.of(members)
-                                            .map(m -> {
+                                                .filterNot(GroupMemberEntry.FullMember::isAdmin)
-                                              Recipient recipient = Recipient.resolved(m);
-                                              return new GroupMemberEntry.FullMember(recipient, g.isAdmin(recipient));
-                                            })
-                                            .sorted(MEMBER_ORDER)
                                                 .toList());
   }
 
+  public LiveData<List<GroupMemberEntry.FullMember>> getFullMembers() {
+    return fullMembers;
+  }
+
   public LiveData<Integer> getExpireMessages() {
     return Transformations.map(recipient, Recipient::getExpireMessages);
   }

app/src/main/java/org/thoughtcrime/securesms/groups/ui/GroupMemberListAdapter.java

@@ -4,6 +4,7 @@ import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.CheckBox;
 import android.widget.ProgressBar;
 import android.widget.TextView;
 
@@ -17,10 +18,11 @@ import org.thoughtcrime.securesms.components.AvatarImageView;
 import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.util.LifecycleRecyclerAdapter;
 import org.thoughtcrime.securesms.util.LifecycleViewHolder;
-import org.thoughtcrime.securesms.util.ThemeUtil;
 
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberListAdapter.ViewHolder> {
 
@@ -29,11 +31,20 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
   private static final int OTHER_INVITE_PENDING_COUNT = 2;
   private static final int NEW_GROUP_CANDIDATE        = 3;
 
-  private final ArrayList<GroupMemberEntry> data = new ArrayList<>();
+  private final List<GroupMemberEntry>  data                    = new ArrayList<>();
+  private final Set<GroupMemberEntry>   selection               = new HashSet<>();
+  private final SelectionChangeListener selectionChangeListener = new SelectionChangeListener();
+
+  private final boolean                 selectable;
 
   @Nullable private AdminActionsListener             adminActionsListener;
   @Nullable private RecipientClickListener           recipientClickListener;
   @Nullable private RecipientLongClickListener       recipientLongClickListener;
+  @Nullable private RecipientSelectionChangeListener recipientSelectionChangeListener;
+
+  GroupMemberListAdapter(boolean selectable) {
+    this.selectable = selectable;
+  }
 
   void updateData(@NonNull List<? extends GroupMemberEntry> recipients) {
     if (data.isEmpty()) {
@@ -43,6 +54,21 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
       DiffUtil.DiffResult diffResult = DiffUtil.calculateDiff(new DiffCallback(data, recipients));
       data.clear();
       data.addAll(recipients);
+
+      if (!selection.isEmpty()) {
+        Set<GroupMemberEntry> newSelection = new HashSet<>();
+        for (GroupMemberEntry entry : recipients) {
+          if (selection.contains(entry)) {
+            newSelection.add(entry);
+          }
+        }
+        selection.clear();
+        selection.addAll(newSelection);
+        if (recipientSelectionChangeListener != null) {
+          recipientSelectionChangeListener.onSelectionChanged(selection);
+        }
+      }
+
       diffResult.dispatchUpdatesTo(this);
     }
   }
@@ -55,22 +81,26 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
                                                       .inflate(R.layout.group_recipient_list_item, parent, false),
                                         recipientClickListener,
                                         recipientLongClickListener,
-                                        adminActionsListener);
+                                        adminActionsListener,
+                                        selectionChangeListener);
       case OWN_INVITE_PENDING:
         return new OwnInvitePendingMemberViewHolder(LayoutInflater.from(parent.getContext())
                                                                   .inflate(R.layout.group_recipient_list_item, parent, false),
                                                     recipientClickListener,
                                                     recipientLongClickListener,
-                                                    adminActionsListener);
+                                                    adminActionsListener,
+                                                    selectionChangeListener);
       case OTHER_INVITE_PENDING_COUNT:
         return new UnknownPendingMemberCountViewHolder(LayoutInflater.from(parent.getContext())
                                                                      .inflate(R.layout.group_recipient_list_item, parent, false),
-                                                       adminActionsListener);
+                                                       adminActionsListener,
+                                                       selectionChangeListener);
       case NEW_GROUP_CANDIDATE:
         return new NewGroupInviteeViewHolder(LayoutInflater.from(parent.getContext())
                                                            .inflate(R.layout.group_new_candidate_recipient_list_item, parent, false),
                                              recipientClickListener,
-                                             recipientLongClickListener);
+                                             recipientLongClickListener,
+                                             selectionChangeListener);
       default:
         throw new AssertionError();
     }
@@ -88,9 +118,14 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
     this.recipientLongClickListener = recipientLongClickListener;
   }
 
+  void setRecipientSelectionChangeListener(@Nullable RecipientSelectionChangeListener recipientSelectionChangeListener) {
+    this.recipientSelectionChangeListener = recipientSelectionChangeListener;
+  }
+
   @Override
   public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
-    holder.bind(data.get(position));
+    GroupMemberEntry entry = data.get(position);
+    holder.bind(entry, selection.contains(entry));
   }
 
   @Override
@@ -120,10 +155,12 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
               final Context                    context;
               final AvatarImageView            avatar;
               final TextView                   recipient;
+              final CheckBox                   selected;
               final PopupMenuView              popupMenu;
               final View                       popupMenuContainer;
               final ProgressBar                busyProgress;
               final View                       admin;
+              final SelectionChangeListener    selectionChangeListener;
     @Nullable final RecipientClickListener     recipientClickListener;
     @Nullable final AdminActionsListener       adminActionsListener;
     @Nullable final RecipientLongClickListener recipientLongClickListener;
@@ -131,13 +168,15 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
     ViewHolder(@NonNull View itemView,
                @Nullable RecipientClickListener recipientClickListener,
                @Nullable RecipientLongClickListener recipientLongClickListener,
-               @Nullable AdminActionsListener adminActionsListener)
+               @Nullable AdminActionsListener adminActionsListener,
+               @NonNull SelectionChangeListener selectionChangeListener)
     {
       super(itemView);
 
       this.context                    = itemView.getContext();
       this.avatar                     = itemView.findViewById(R.id.recipient_avatar);
       this.recipient                  = itemView.findViewById(R.id.recipient_name);
+      this.selected                   = itemView.findViewById(R.id.recipient_selected);
       this.popupMenu                  = itemView.findViewById(R.id.popupMenu);
       this.popupMenuContainer         = itemView.findViewById(R.id.popupMenuProgressContainer);
       this.busyProgress               = itemView.findViewById(R.id.menuBusyProgress);
@@ -145,6 +184,7 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
       this.recipientClickListener     = recipientClickListener;
       this.recipientLongClickListener = recipientLongClickListener;
       this.adminActionsListener       = adminActionsListener;
+      this.selectionChangeListener    = selectionChangeListener;
     }
 
     void bindRecipient(@NonNull Recipient recipient) {
@@ -166,20 +206,22 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
 
       this.itemView.setEnabled(true);
       this.itemView.setOnClickListener(v -> {
-        if (recipientClickListener != null && getAdapterPosition() != RecyclerView.NO_POSITION) {
+        if (getAdapterPosition() != RecyclerView.NO_POSITION) {
+          if (recipientClickListener != null) {
             recipientClickListener.onClick(recipient);
           }
+          selectionChangeListener.onSelectionChange(getAdapterPosition(), !selected.isChecked());
+        }
       });
       this.itemView.setOnLongClickListener(v -> {
         if (recipientLongClickListener != null && getAdapterPosition() != RecyclerView.NO_POSITION) {
           return recipientLongClickListener.onLongClick(recipient);
         }
-
         return false;
       });
     }
 
-    void bind(@NonNull GroupMemberEntry memberEntry) {
+    void bind(@NonNull GroupMemberEntry memberEntry, boolean isSelected) {
       busyProgress.setVisibility(View.GONE);
       admin.setVisibility(View.GONE);
       hideMenu();
@@ -190,6 +232,8 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
         busyProgress.setVisibility(busy ? View.VISIBLE : View.GONE);
         popupMenu.setVisibility(busy ? View.GONE : View.VISIBLE);
       });
+
+      selected.setChecked(isSelected);
     }
 
     void hideMenu() {
@@ -208,14 +252,15 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
     FullMemberViewHolder(@NonNull View itemView,
                          @Nullable RecipientClickListener recipientClickListener,
                          @Nullable RecipientLongClickListener recipientLongClickListener,
-                         @Nullable AdminActionsListener adminActionsListener)
+                         @Nullable AdminActionsListener adminActionsListener,
+                         @NonNull SelectionChangeListener selectionChangeListener)
     {
-      super(itemView, recipientClickListener, recipientLongClickListener, adminActionsListener);
+      super(itemView, recipientClickListener, recipientLongClickListener, adminActionsListener, selectionChangeListener);
     }
 
     @Override
-    void bind(@NonNull GroupMemberEntry memberEntry) {
+    void bind(@NonNull GroupMemberEntry memberEntry, boolean isSelected) {
-      super.bind(memberEntry);
+      super.bind(memberEntry, isSelected);
 
       GroupMemberEntry.FullMember fullMember = (GroupMemberEntry.FullMember) memberEntry;
 
@@ -231,16 +276,17 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
 
     NewGroupInviteeViewHolder(@NonNull View itemView,
                               @Nullable RecipientClickListener recipientClickListener,
-                              @Nullable RecipientLongClickListener recipientLongClickListener)
+                              @Nullable RecipientLongClickListener recipientLongClickListener,
+                              @NonNull SelectionChangeListener selectionChangeListener)
     {
-      super(itemView, recipientClickListener, recipientLongClickListener, null);
+      super(itemView, recipientClickListener, recipientLongClickListener, null, selectionChangeListener);
 
       smsContact = itemView.findViewById(R.id.sms_contact);
       smsWarning = itemView.findViewById(R.id.sms_warning);
     }
 
     @Override
-    void bind(@NonNull GroupMemberEntry memberEntry) {
+    void bind(@NonNull GroupMemberEntry memberEntry, boolean isSelected) {
       GroupMemberEntry.NewGroupCandidate newGroupCandidate = (GroupMemberEntry.NewGroupCandidate) memberEntry;
 
       bindRecipient(newGroupCandidate.getMember());
@@ -258,14 +304,15 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
     OwnInvitePendingMemberViewHolder(@NonNull View itemView,
                                      @Nullable RecipientClickListener recipientClickListener,
                                      @Nullable RecipientLongClickListener recipientLongClickListener,
-                         @Nullable AdminActionsListener adminActionsListener)
+                                     @Nullable AdminActionsListener adminActionsListener,
+                                     @NonNull SelectionChangeListener selectionChangeListener)
     {
-      super(itemView, recipientClickListener, recipientLongClickListener, adminActionsListener);
+      super(itemView, recipientClickListener, recipientLongClickListener, adminActionsListener, selectionChangeListener);
     }
 
     @Override
-    void bind(@NonNull GroupMemberEntry memberEntry) {
+    void bind(@NonNull GroupMemberEntry memberEntry, boolean isSelected) {
-      super.bind(memberEntry);
+      super.bind(memberEntry, isSelected);
 
       GroupMemberEntry.PendingMember pendingMember = (GroupMemberEntry.PendingMember) memberEntry;
 
@@ -288,13 +335,16 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
 
   final static class UnknownPendingMemberCountViewHolder extends ViewHolder {
 
-    UnknownPendingMemberCountViewHolder(@NonNull View itemView, @Nullable AdminActionsListener adminActionsListener) {
+    UnknownPendingMemberCountViewHolder(@NonNull View itemView,
-      super(itemView, null, null, adminActionsListener);
+                                        @Nullable AdminActionsListener adminActionsListener,
+                                        @NonNull SelectionChangeListener selectionChangeListener)
+    {
+      super(itemView, null, null, adminActionsListener, selectionChangeListener);
     }
 
     @Override
-    void bind(@NonNull GroupMemberEntry memberEntry) {
+    void bind(@NonNull GroupMemberEntry memberEntry, boolean isSelected) {
-      super.bind(memberEntry);
+      super.bind(memberEntry, isSelected);
       GroupMemberEntry.UnknownPendingMemberCount pendingMembers = (GroupMemberEntry.UnknownPendingMemberCount) memberEntry;
 
       Recipient inviter     = pendingMembers.getInviter();
@@ -327,6 +377,23 @@ final class GroupMemberListAdapter extends LifecycleRecyclerAdapter<GroupMemberL
     }
   }
 
+  private final class SelectionChangeListener {
+    void onSelectionChange(int position, boolean isChecked) {
+      if (selectable) {
+        if (isChecked) {
+          selection.add(data.get(position));
+        } else {
+          selection.remove(data.get(position));
+        }
+        notifyItemChanged(position);
+
+        if (recipientSelectionChangeListener != null) {
+          recipientSelectionChangeListener.onSelectionChanged(selection);
+        }
+      }
+    }
+  }
+
   private final static class DiffCallback extends DiffUtil.Callback {
     private final List<? extends GroupMemberEntry> oldData;
     private final List<? extends GroupMemberEntry> newData;

app/src/main/java/org/thoughtcrime/securesms/groups/ui/GroupMemberListView.java

@@ -15,7 +15,7 @@ import java.util.List;
 
 public final class GroupMemberListView extends RecyclerView {
 
-  private final GroupMemberListAdapter membersAdapter = new GroupMemberListAdapter();
+  private GroupMemberListAdapter membersAdapter;
   private int                    maxHeight;
 
   public GroupMemberListView(@NonNull Context context) {
@@ -38,17 +38,20 @@ public final class GroupMemberListView extends RecyclerView {
       setHasFixedSize(true);
     }
 
-    setLayoutManager(new LinearLayoutManager(context));
+    boolean selectable = false;
-    setAdapter(membersAdapter);
-
     if (attrs != null) {
       TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.GroupMemberListView, 0, 0);
       try {
         maxHeight = typedArray.getDimensionPixelSize(R.styleable.GroupMemberListView_maxHeight, 0);
+        selectable = typedArray.getBoolean(R.styleable.GroupMemberListView_selectable, false);
       } finally {
         typedArray.recycle();
       }
     }
+
+    membersAdapter = new GroupMemberListAdapter(selectable);
+    setLayoutManager(new LinearLayoutManager(context));
+    setAdapter(membersAdapter);
   }
 
   public void setAdminActionsListener(@Nullable AdminActionsListener adminActionsListener) {
@@ -63,6 +66,10 @@ public final class GroupMemberListView extends RecyclerView {
     membersAdapter.setRecipientLongClickListener(listener);
   }
 
+  public void setRecipientSelectionChangeListener(@Nullable RecipientSelectionChangeListener listener) {
+    membersAdapter.setRecipientSelectionChangeListener(listener);
+  }
+
   public void setMembers(@NonNull List<? extends GroupMemberEntry> recipients) {
     membersAdapter.updateData(recipients);
   }

app/src/main/java/org/thoughtcrime/securesms/groups/ui/LeaveGroupDialog.java

@@ -1,60 +1,115 @@
 package org.thoughtcrime.securesms.groups.ui;
 
-import android.content.Context;
 import android.widget.Toast;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
-import androidx.lifecycle.Lifecycle;
+import androidx.fragment.app.FragmentActivity;
+
+import com.annimon.stream.Stream;
 
 import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.database.DatabaseFactory;
+import org.thoughtcrime.securesms.database.GroupDatabase;
 import org.thoughtcrime.securesms.groups.GroupChangeBusyException;
 import org.thoughtcrime.securesms.groups.GroupChangeFailedException;
 import org.thoughtcrime.securesms.groups.GroupId;
 import org.thoughtcrime.securesms.groups.GroupManager;
+import org.thoughtcrime.securesms.groups.ui.chooseadmin.ChooseNewAdminActivity;
 import org.thoughtcrime.securesms.logging.Log;
+import org.thoughtcrime.securesms.recipients.Recipient;
 import org.thoughtcrime.securesms.util.concurrent.SimpleTask;
 
 import java.io.IOException;
+import java.util.List;
 
 public final class LeaveGroupDialog {
 
   private static final String TAG = Log.tag(LeaveGroupDialog.class);
 
-  private LeaveGroupDialog() {
+  @NonNull  private final FragmentActivity activity;
+  @NonNull  private final GroupId.Push     groupId;
+  @Nullable private final Runnable         onSuccess;
+
+  public static void handleLeavePushGroup(@NonNull FragmentActivity activity,
+                                          @NonNull GroupId.Push groupId,
+                                          @Nullable Runnable onSuccess) {
+    new LeaveGroupDialog(activity, groupId, onSuccess).show();
   }
 
-  public static void handleLeavePushGroup(@NonNull Context context,
+  private LeaveGroupDialog(@NonNull FragmentActivity activity,
-                                          @NonNull Lifecycle lifecycle,
                            @NonNull GroupId.Push groupId,
-                                          @Nullable Runnable onSuccess)
+                           @Nullable Runnable onSuccess) {
-  {
+    this.activity  = activity;
-    new AlertDialog.Builder(context)
+    this.groupId   = groupId;
-                   .setTitle(context.getString(R.string.ConversationActivity_leave_group))
+    this.onSuccess = onSuccess;
+  }
+
+  public void show() {
+    if (!groupId.isV2()) {
+      showLeaveDialog();
+      return;
+    }
+
+    SimpleTask.run(activity.getLifecycle(), () -> {
+      GroupDatabase.V2GroupProperties groupProperties = DatabaseFactory.getGroupDatabase(activity)
+                                                                       .getGroup(groupId)
+                                                                       .transform(GroupDatabase.GroupRecord::requireV2GroupProperties)
+                                                                       .orNull();
+
+      if (groupProperties != null && groupProperties.isAdmin(Recipient.self())) {
+        List<Recipient> otherMemberRecipients = groupProperties.getMemberRecipients(GroupDatabase.MemberSet.FULL_MEMBERS_EXCLUDING_SELF);
+        long            otherAdminsCount      = Stream.of(otherMemberRecipients).filter(groupProperties::isAdmin).count();
+
+        return otherAdminsCount == 0 && !otherMemberRecipients.isEmpty();
+      }
+
+      return false;
+    }, mustSelectNewAdmin -> {
+      if (mustSelectNewAdmin) {
+        showSelectNewAdminDialog();
+      } else {
+        showLeaveDialog();
+      }
+    });
+  }
+
+  private void showSelectNewAdminDialog() {
+    new AlertDialog.Builder(activity)
+                   .setTitle(R.string.ConversationActivity_choose_new_admin)
+                   .setMessage(R.string.ConversationActivity_before_you_leave_you_must_choose_at_least_one_new_admin_for_this_group)
+                   .setNegativeButton(android.R.string.cancel, null)
+                   .setPositiveButton(R.string.ConversationActivity_choose_admin, (d,w) -> activity.startActivity(ChooseNewAdminActivity.createIntent(activity, groupId.requireV2())))
+                   .show();
+  }
+
+  private void showLeaveDialog() {
+    new AlertDialog.Builder(activity)
+                   .setTitle(R.string.ConversationActivity_leave_group)
                    .setIconAttribute(R.attr.dialog_info_icon)
                    .setCancelable(true)
-                   .setMessage(context.getString(R.string.ConversationActivity_are_you_sure_you_want_to_leave_this_group))
+                   .setMessage(R.string.ConversationActivity_are_you_sure_you_want_to_leave_this_group)
-                   .setPositiveButton(R.string.yes, (dialog, which) ->
+                   .setPositiveButton(R.string.yes, (dialog, which) -> SimpleTask.run(activity.getLifecycle(), this::leaveGroup, this::handleLeaveGroupResult))
-                      SimpleTask.run(
+                   .setNegativeButton(R.string.no, null)
-                        lifecycle,
+                   .show();
-                        () -> {
+  }
+
+  private boolean leaveGroup() {
     try {
-                            GroupManager.leaveGroup(context, groupId);
+      GroupManager.leaveGroup(activity, groupId);
       return true;
     } catch (GroupChangeFailedException | GroupChangeBusyException | IOException e) {
       Log.w(TAG, e);
       return false;
     }
-                        },
+  }
-                       (success) -> {
+
+  private void handleLeaveGroupResult(boolean success) {
     if (success) {
       if (onSuccess != null) onSuccess.run();
     } else {
-                            Toast.makeText(context, R.string.ConversationActivity_error_leaving_group, Toast.LENGTH_LONG).show();
+      Toast.makeText(activity, R.string.ConversationActivity_error_leaving_group, Toast.LENGTH_LONG).show();
     }
-                        }))
-                   .setNegativeButton(R.string.no, null)
-                   .show();
   }
 }

app/src/main/java/org/thoughtcrime/securesms/groups/ui/RecipientSelectionChangeListener.java

@@ -0,0 +1,9 @@
+package org.thoughtcrime.securesms.groups.ui;
+
+import androidx.annotation.NonNull;
+
+import java.util.Set;
+
+public interface RecipientSelectionChangeListener {
+  void onSelectionChanged(@NonNull Set<GroupMemberEntry> selection);
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/chooseadmin/ChooseNewAdminActivity.java

@@ -0,0 +1,124 @@
+package org.thoughtcrime.securesms.groups.ui.chooseadmin;
+
+import android.content.Context;
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.view.View;
+import android.widget.Toast;
+
+import androidx.annotation.NonNull;
+import androidx.appcompat.widget.Toolbar;
+import androidx.lifecycle.ViewModelProviders;
+
+import com.annimon.stream.Collectors;
+import com.annimon.stream.Stream;
+import com.dd.CircularProgressButton;
+
+import org.thoughtcrime.securesms.MainActivity;
+import org.thoughtcrime.securesms.PassphraseRequiredActivity;
+import org.thoughtcrime.securesms.R;
+import org.thoughtcrime.securesms.groups.BadGroupIdException;
+import org.thoughtcrime.securesms.groups.GroupId;
+import org.thoughtcrime.securesms.groups.ui.GroupErrors;
+import org.thoughtcrime.securesms.groups.ui.GroupMemberEntry;
+import org.thoughtcrime.securesms.groups.ui.GroupMemberListView;
+import org.thoughtcrime.securesms.groups.ui.chooseadmin.ChooseNewAdminRepository.UpdateResult;
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.util.DynamicNoActionBarTheme;
+import org.thoughtcrime.securesms.util.DynamicTheme;
+
+import java.util.Objects;
+
+public final class ChooseNewAdminActivity extends PassphraseRequiredActivity {
+
+  private static final String EXTRA_GROUP_ID = "group_id";
+
+  private ChooseNewAdminViewModel viewModel;
+  private GroupMemberListView     groupList;
+  private CircularProgressButton  done;
+  private GroupId.V2              groupId;
+
+  private final DynamicTheme dynamicTheme = new DynamicNoActionBarTheme();
+
+  public static Intent createIntent(@NonNull Context context, @NonNull GroupId.V2 groupId) {
+    Intent intent = new Intent(context, ChooseNewAdminActivity.class);
+    intent.putExtra(EXTRA_GROUP_ID, groupId.toString());
+    return intent;
+  }
+
+  @Override
+  protected void onPreCreate() {
+    dynamicTheme.onCreate(this);
+  }
+
+  @Override
+  protected void onCreate(Bundle savedInstanceState, boolean ready) {
+    super.onCreate(savedInstanceState, ready);
+    setContentView(R.layout.choose_new_admin_activity);
+
+    Toolbar toolbar = findViewById(R.id.toolbar);
+    setSupportActionBar(toolbar);
+    //noinspection ConstantConditions
+    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+
+    try {
+      groupId = GroupId.parse(Objects.requireNonNull(getIntent().getStringExtra(EXTRA_GROUP_ID))).requireV2();
+    } catch (BadGroupIdException e) {
+      throw new AssertionError(e);
+    }
+
+    groupList = findViewById(R.id.choose_new_admin_group_list);
+    done      = findViewById(R.id.choose_new_admin_done);
+    done.setIndeterminateProgressMode(true);
+
+    initializeViewModel();
+
+    groupList.setRecipientSelectionChangeListener(selection -> viewModel.setSelection(Stream.of(selection)
+                                                                                            .select(GroupMemberEntry.FullMember.class)
+                                                                                            .collect(Collectors.toSet())));
+
+    done.setOnClickListener(v -> {
+      done.setClickable(false);
+      done.setProgress(50);
+      viewModel.updateAdminsAndLeave(this::handleUpdateAndLeaveResult);
+    });
+  }
+
+  @Override
+  protected void onResume() {
+    super.onResume();
+    dynamicTheme.onResume(this);
+  }
+
+  @Override
+  public boolean onOptionsItemSelected(MenuItem item) {
+    if (item.getItemId() == android.R.id.home) {
+      finish();
+      return true;
+    }
+
+    return super.onOptionsItemSelected(item);
+  }
+
+  private void initializeViewModel() {
+    viewModel = ViewModelProviders.of(this, new ChooseNewAdminViewModel.Factory(groupId)).get(ChooseNewAdminViewModel.class);
+
+    viewModel.getNonAdminFullMembers().observe(this, groupList::setMembers);
+    viewModel.getSelection().observe(this, selection -> done.setVisibility(selection.isEmpty() ? View.GONE : View.VISIBLE));
+  }
+
+  private void handleUpdateAndLeaveResult(@NonNull UpdateResult updateResult) {
+    if (updateResult.isSuccess()) {
+      String title = Recipient.externalGroup(this, groupId).getDisplayName(this);
+      Toast.makeText(this, getString(R.string.ChooseNewAdminActivity_you_left, title), Toast.LENGTH_LONG).show();
+      startActivity(new Intent(this, MainActivity.class));
+      finish();
+    } else {
+      done.setClickable(true);
+      done.setProgress(0);
+      //noinspection ConstantConditions
+      Toast.makeText(this, GroupErrors.getUserDisplayMessage(updateResult.getFailureReason()), Toast.LENGTH_LONG).show();
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/chooseadmin/ChooseNewAdminRepository.java

@@ -0,0 +1,62 @@
+package org.thoughtcrime.securesms.groups.ui.chooseadmin;
+
+import android.app.Application;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.WorkerThread;
+import androidx.core.util.Consumer;
+
+import org.thoughtcrime.securesms.groups.GroupChangeBusyException;
+import org.thoughtcrime.securesms.groups.GroupChangeFailedException;
+import org.thoughtcrime.securesms.groups.GroupId;
+import org.thoughtcrime.securesms.groups.GroupInsufficientRightsException;
+import org.thoughtcrime.securesms.groups.GroupManager;
+import org.thoughtcrime.securesms.groups.GroupNotAMemberException;
+import org.thoughtcrime.securesms.groups.ui.GroupChangeFailureReason;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+
+import java.io.IOException;
+import java.util.List;
+
+public final class ChooseNewAdminRepository {
+  private Application context;
+
+  ChooseNewAdminRepository(@NonNull Application context) {
+    this.context = context;
+  }
+
+  @WorkerThread
+  @NonNull UpdateResult updateAdminsAndLeave(@NonNull GroupId.V2 groupId, @NonNull List<RecipientId> newAdminIds) {
+    try {
+      GroupManager.addMemberAdminsAndLeaveGroup(context, groupId, newAdminIds);
+      return new UpdateResult();
+    } catch (GroupInsufficientRightsException e) {
+      return new UpdateResult(GroupChangeFailureReason.NO_RIGHTS);
+    } catch (GroupNotAMemberException e) {
+      return new UpdateResult(GroupChangeFailureReason.NOT_A_MEMBER);
+    } catch (GroupChangeFailedException | GroupChangeBusyException | IOException e) {
+      return new UpdateResult(GroupChangeFailureReason.OTHER);
+    }
+  }
+
+  static final class UpdateResult {
+    final @Nullable GroupChangeFailureReason failureReason;
+
+    UpdateResult() {
+      this(null);
+    }
+
+    UpdateResult(@Nullable GroupChangeFailureReason failureReason) {
+      this.failureReason = failureReason;
+    }
+
+    boolean isSuccess() {
+      return failureReason == null;
+    }
+
+    @Nullable GroupChangeFailureReason getFailureReason() {
+      return failureReason;
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/chooseadmin/ChooseNewAdminViewModel.java

@@ -0,0 +1,76 @@
+package org.thoughtcrime.securesms.groups.ui.chooseadmin;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.StringRes;
+import androidx.core.util.Consumer;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+import androidx.lifecycle.Transformations;
+import androidx.lifecycle.ViewModel;
+import androidx.lifecycle.ViewModelProvider;
+
+import com.annimon.stream.Stream;
+
+import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
+import org.thoughtcrime.securesms.groups.GroupId;
+import org.thoughtcrime.securesms.groups.LiveGroup;
+import org.thoughtcrime.securesms.groups.ui.GroupErrors;
+import org.thoughtcrime.securesms.groups.ui.GroupMemberEntry;
+import org.thoughtcrime.securesms.groups.ui.chooseadmin.ChooseNewAdminRepository.UpdateResult;
+import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.recipients.RecipientId;
+import org.thoughtcrime.securesms.util.concurrent.SimpleTask;
+import org.thoughtcrime.securesms.util.livedata.LiveDataUtil;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+
+final class ChooseNewAdminViewModel extends ViewModel {
+
+  private final GroupId.V2                                        groupId;
+  private final ChooseNewAdminRepository                          repository;
+  private final LiveGroup                                         liveGroup;
+  private final MutableLiveData<Set<GroupMemberEntry.FullMember>> selection;
+
+  public ChooseNewAdminViewModel(@NonNull GroupId.V2 groupId, @NonNull ChooseNewAdminRepository repository) {
+    this.groupId    = groupId;
+    this.repository = repository;
+
+    liveGroup = new LiveGroup(groupId);
+    selection = new MutableLiveData<>(Collections.emptySet());
+  }
+
+  @NonNull LiveData<List<GroupMemberEntry.FullMember>> getNonAdminFullMembers() {
+    return liveGroup.getNonAdminFullMembers();
+  }
+
+  @NonNull LiveData<Set<GroupMemberEntry.FullMember>> getSelection() {
+    return selection;
+  }
+
+  void setSelection(@NonNull Set<GroupMemberEntry.FullMember> selection) {
+    this.selection.setValue(selection);
+  }
+
+  void updateAdminsAndLeave(@NonNull Consumer<UpdateResult> consumer) {
+    //noinspection ConstantConditions
+    List<RecipientId> recipientIds = Stream.of(selection.getValue()).map(entry -> entry.getMember().getId()).toList();
+    SimpleTask.run(() -> repository.updateAdminsAndLeave(groupId, recipientIds), consumer::accept);
+  }
+
+  static final class Factory implements ViewModelProvider.Factory {
+
+    private final GroupId.V2 groupId;
+
+    Factory(@NonNull GroupId.V2 groupId) {
+      this.groupId = groupId;
+    }
+
+    @Override
+    public @NonNull <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
+      //noinspection ConstantConditions
+      return modelClass.cast(new ChooseNewAdminViewModel(groupId, new ChooseNewAdminRepository(ApplicationDependencies.getApplication())));
+    }
+  }
+}

app/src/main/java/org/thoughtcrime/securesms/groups/ui/managegroup/ManageGroupFragment.java

@@ -24,6 +24,7 @@ import com.google.android.material.snackbar.Snackbar;
 
 import org.thoughtcrime.securesms.AvatarPreviewActivity;
 import org.thoughtcrime.securesms.LoggingFragment;
+import org.thoughtcrime.securesms.MainActivity;
 import org.thoughtcrime.securesms.MediaPreviewActivity;
 import org.thoughtcrime.securesms.MuteDialog;
 import org.thoughtcrime.securesms.PushContactSelectionActivity;
@@ -234,10 +235,7 @@ public class ManageGroupFragment extends LoggingFragment {
     });
 
     leaveGroup.setVisibility(groupId.isPush() ? View.VISIBLE : View.GONE);
-    leaveGroup.setOnClickListener(v -> LeaveGroupDialog.handleLeavePushGroup(context,
+    leaveGroup.setOnClickListener(v -> LeaveGroupDialog.handleLeavePushGroup(requireActivity(), groupId.requirePush(), () -> startActivity(new Intent(requireActivity(), MainActivity.class))));
-                                                                             getLifecycle(),
-                                                                             groupId.requirePush(),
-                                                                             null));
 
     viewModel.getDisappearingMessageTimer().observe(getViewLifecycleOwner(), string -> disappearingMessages.setText(string));
 

app/src/main/res/layout/choose_new_admin_activity.xml

@@ -0,0 +1,57 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:orientation="vertical">
+
+    <com.google.android.material.appbar.AppBarLayout
+        android:id="@+id/toolbar_layout"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:background="?android:attr/windowBackground"
+        app:elevation="0dp">
+
+        <androidx.appcompat.widget.Toolbar
+            android:id="@+id/toolbar"
+            android:layout_width="match_parent"
+            android:layout_height="?actionBarSize"
+            android:background="@android:color/transparent"
+            app:title="@string/ChooseNewAdminActivity_choose_new_admin"
+            app:titleTextColor="?title_text_color_primary" />
+
+    </com.google.android.material.appbar.AppBarLayout>
+
+    <FrameLayout android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_gravity="center"
+        android:layout_weight="1"
+        android:orientation="vertical">
+
+        <org.thoughtcrime.securesms.groups.ui.GroupMemberListView
+            android:id="@+id/choose_new_admin_group_list"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:selectable="true"
+            tools:listitem="@layout/group_recipient_list_item" />
+
+        <com.dd.CircularProgressButton
+            android:id="@+id/choose_new_admin_done"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="bottom|end"
+            android:layout_marginEnd="16dp"
+            android:layout_marginBottom="16dp"
+            android:textColor="@color/white"
+            app:cpb_colorIndicator="@color/white"
+            app:cpb_colorProgress="?colorAccent"
+            app:cpb_cornerRadius="28dp"
+            app:cpb_selectorIdle="?attr/circular_progress_button_state"
+            app:cpb_textIdle="@string/ChooseNewAdminActivity_done"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent" />
+
+    </FrameLayout>
+
+</LinearLayout>

app/src/main/res/layout/group_recipient_list_item.xml

@@ -15,7 +15,20 @@
         android:layout_marginStart="16dp"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toTopOf="parent"
+        tools:src="@tools:sample/avatars"/>
+
+    <androidx.appcompat.widget.AppCompatCheckBox
+        android:id="@+id/recipient_selected"
+        android:background="?attr/contact_selection_checkbox_background"
+        android:button="@null"
+        android:layout_width="22dp"
+        android:layout_height="22dp"
+        android:focusable="false"
+        android:clickable="false"
+        app:layout_constraintBottom_toBottomOf="@+id/recipient_avatar"
+        app:layout_constraintEnd_toEndOf="@+id/recipient_avatar"
+        tools:checked="true"/>
 
     <TextView
         android:id="@+id/recipient_name"

app/src/main/res/values/attrs.xml

@@ -529,6 +529,7 @@
 
     <declare-styleable name="GroupMemberListView">
         <attr name="maxHeight" />
+        <attr name="selectable" format="boolean" />
     </declare-styleable>
 
     <declare-styleable name="WebRtcAudioOutputToggleButtonState">

app/src/main/res/values/strings.xml

@@ -227,6 +227,9 @@
     <string name="ConversationActivity_this_device_does_not_appear_to_support_dial_actions">This device does not appear to support dial actions.</string>
     <string name="ConversationActivity_leave_group">Leave group?</string>
     <string name="ConversationActivity_are_you_sure_you_want_to_leave_this_group">Are you sure you want to leave this group?</string>
+    <string name="ConversationActivity_choose_new_admin">Choose new admin</string>
+    <string name="ConversationActivity_before_you_leave_you_must_choose_at_least_one_new_admin_for_this_group">Before you leave, you must choose at least one new admin for this group.</string>
+    <string name="ConversationActivity_choose_admin">Choose admin</string>
     <string name="ConversationActivity_transport_insecure_sms">Insecure SMS</string>
     <string name="ConversationActivity_transport_insecure_mms">Insecure MMS</string>
     <string name="ConversationActivity_transport_signal">Signal</string>
@@ -442,6 +445,11 @@
     <string name="AddToGroupActivity_add_to_group">Add to group</string>
     <string name="AddToGroupActivity_add_to_groups">Add to groups</string>
 
+    <!-- ChooseNewAdminActivity -->
+    <string name="ChooseNewAdminActivity_choose_new_admin">Choose new admin</string>
+    <string name="ChooseNewAdminActivity_done">Done</string>
+    <string name="ChooseNewAdminActivity_you_left">You left \"%1$s.\"</string>
+
     <!-- GroupShareProfileView -->
     <string name="GroupShareProfileView_share_your_profile_name_and_photo_with_this_group">Share your profile name and photo with this group?</string>
     <string name="GroupShareProfileView_do_you_want_to_make_your_profile_name_and_photo_visible_to_all_current_and_future_members_of_this_group">Do you want to make your profile name and photo visible to all current and future members of this group?</string>

libsignal/service/src/main/java/org/whispersystems/signalservice/api/groupsv2/GroupsV2Operations.java

@@ -207,6 +207,18 @@ public final class GroupsV2Operations {
       return actions;
     }
 
+    public GroupChange.Actions.Builder createLeaveAndPromoteMembersToAdmin(UUID self, List<UUID> membersToMakeAdmin) {
+      GroupChange.Actions.Builder actions = createRemoveMembersChange(Collections.singleton(self));
+
+      for (UUID member : membersToMakeAdmin) {
+        actions.addModifyMemberRoles(GroupChange.Actions.ModifyMemberRoleAction.newBuilder()
+                                                                               .setUserId(encryptUuid(member))
+                                                                               .setRole(Member.Role.ADMINISTRATOR));
+      }
+
+      return actions;
+    }
+
     public GroupChange.Actions.Builder createModifyGroupTimerChange(int timerDurationSeconds) {
       return GroupChange.Actions
                         .newBuilder()