Merge branch '1881-thread-list-controller' into 'master'

Migrate ThreadListController to ViewModel

Closes #1881, #1873, and #1870

See merge request briar/briar!1336

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -35,9 +35,11 @@ import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
+import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 import org.briarproject.briar.android.settings.SettingsModule;
 import org.briarproject.briar.android.privategroup.list.GroupListModule;
 import org.briarproject.briar.android.reporting.DevReportModule;
+import org.briarproject.briar.android.sharing.SharingModule;
 import org.briarproject.briar.android.test.TestAvatarCreatorImpl;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
@@ -79,8 +81,10 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		DevReportModule.class,
 		ContactListModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
-		ForumModule.BindsModule.class,
+		ForumModule.class,
 		GroupListModule.class,
+		GroupConversationModule.class,
+		SharingModule.class,
 })
 public class AppModule {
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -32,7 +32,6 @@ import org.briarproject.briar.android.conversation.ImageFragment;
 import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
-import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
@@ -50,7 +49,6 @@ import org.briarproject.briar.android.navdrawer.TransportsActivity;
 import org.briarproject.briar.android.panic.PanicPreferencesActivity;
 import org.briarproject.briar.android.panic.PanicResponderActivity;
 import org.briarproject.briar.android.privategroup.conversation.GroupActivity;
-import org.briarproject.briar.android.privategroup.conversation.GroupConversationModule;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupActivity;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupFragment;
 import org.briarproject.briar.android.privategroup.creation.CreateGroupModule;
@@ -89,12 +87,10 @@ import dagger.Component;
 		ActivityModule.class,
 		BlogModule.class,
 		CreateGroupModule.class,
-		ForumModule.class,
 		GroupInvitationModule.class,
-		GroupConversationModule.class,
 		GroupMemberModule.class,
 		GroupRevealModule.class,
-		SharingModule.class
+		SharingModule.SharingLegacyModule.class
 }, dependencies = AndroidComponent.class)
 public interface ActivityComponent {
 

briar-android/src/main/java/org/briarproject/briar/android/activity/BaseActivity.java

@@ -14,7 +14,6 @@ import org.briarproject.briar.android.BriarApplication;
 import org.briarproject.briar.android.DestroyableContext;
 import org.briarproject.briar.android.Localizer;
 import org.briarproject.briar.android.controller.ActivityLifecycleController;
-import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.util.UiUtils;
@@ -87,7 +86,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		activityComponent = DaggerActivityComponent.builder()
 				.androidComponent(applicationComponent)
 				.activityModule(getActivityModule())
-				.forumModule(getForumModule())
 				.build();
 		injectActivity(activityComponent);
 		super.onCreate(state);
@@ -122,11 +120,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		return new ActivityModule(this);
 	}
 
-	// TODO use a test module where this is used in tests
-	protected ForumModule getForumModule() {
-		return new ForumModule();
-	}
-
 	@Override
 	protected void onStart() {
 		super.onStart();

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -160,7 +160,6 @@ public abstract class BriarActivity extends BaseActivity {
 	 * @param ownLayout true if the custom toolbar brings its own layout
 	 * @return the Toolbar object or null if content view did not contain one
 	 */
-	@Nullable
 	protected Toolbar setUpCustomToolbar(boolean ownLayout) {
 		// Custom Toolbar
 		Toolbar toolbar = findViewById(R.id.toolbar);

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingController.java

@@ -7,6 +7,7 @@ import java.util.Collection;
 
 import androidx.annotation.UiThread;
 
+@Deprecated
 @NotNullByDefault
 public interface SharingController {
 

briar-android/src/main/java/org/briarproject/briar/android/controller/SharingControllerImpl.java

@@ -18,6 +18,7 @@ import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
 
+@Deprecated
 @NotNullByDefault
 public class SharingControllerImpl implements SharingController, EventListener {
 

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumActivity.java

@@ -6,52 +6,54 @@ import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
-import android.widget.Toast;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.android.forum.ForumController.ForumListener;
 import org.briarproject.briar.android.sharing.ForumSharingStatusActivity;
 import org.briarproject.briar.android.sharing.ShareForumActivity;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter;
 import org.briarproject.briar.android.threaded.ThreadListActivity;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.forum.Forum;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.widget.Toolbar;
-import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
-import static android.widget.Toast.LENGTH_SHORT;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_FORUM;
+import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.api.forum.ForumConstants.MAX_FORUM_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ForumActivity extends
-		ThreadListActivity<Forum, ForumPostItem, ThreadItemAdapter<ForumPostItem>>
-		implements ForumListener {
+		ThreadListActivity<ForumPostItem, ThreadItemAdapter<ForumPostItem>> {
 
 	@Inject
-	ForumController forumController;
+	ViewModelProvider.Factory viewModelFactory;
+
+	private ForumViewModel viewModel;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(ForumViewModel.class);
 	}
 
 	@Override
-	protected ThreadListController<Forum, ForumPostItem> getController() {
-		return forumController;
+	protected ThreadListViewModel<ForumPostItem> getViewModel() {
+		return viewModel;
+	}
+
+	@Override
+	protected ThreadItemAdapter<ForumPostItem> createAdapter() {
+		return new ThreadItemAdapter<>(this);
 	}
 
 	@Override
@@ -59,36 +61,27 @@ public class ForumActivity extends
 		super.onCreate(state);
 
 		Toolbar toolbar = setUpCustomToolbar(false);
-
-		Intent i = getIntent();
-		String groupName = i.getStringExtra(GROUP_NAME);
-		if (groupName != null) setTitle(groupName);
-		else loadNamedGroup();
-
 		// Open member list on Toolbar click
-		if (toolbar != null) {
-			toolbar.setOnClickListener(v -> {
-				Intent i1 = new Intent(ForumActivity.this,
-						ForumSharingStatusActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-			});
+		toolbar.setOnClickListener(v -> {
+			Intent i = new Intent(ForumActivity.this,
+					ForumSharingStatusActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+		});
+
+		String groupName = getIntent().getStringExtra(GROUP_NAME);
+		if (groupName != null) {
+			setTitle(groupName);
+		} else {
+			observeOnce(viewModel.loadForum(), this, forum ->
+					setTitle(forum.getName())
+			);
 		}
 	}
 
 	@Override
-	protected void onNamedGroupLoaded(Forum forum) {
-		setTitle(forum.getName());
-	}
-
-	@Override
-	protected ThreadItemAdapter<ForumPostItem> createAdapter(
-			LinearLayoutManager layoutManager) {
-		return new ThreadItemAdapter<>(this, layoutManager);
-	}
-
-	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 
 		if (request == REQUEST_SHARE_FORUM && result == RESULT_OK) {
@@ -101,32 +94,31 @@ public class ForumActivity extends
 		// Inflate the menu items for use in the action bar
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.forum_actions, menu);
-
-		return super.onCreateOptionsMenu(menu);
+		super.onCreateOptionsMenu(menu);
+		return true;
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		// Handle presses on the action bar items
-		switch (item.getItemId()) {
-			case R.id.action_forum_share:
-				Intent i2 = new Intent(this, ShareForumActivity.class);
-				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i2.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i2, REQUEST_SHARE_FORUM);
-				return true;
-			case R.id.action_forum_sharing_status:
-				Intent i3 = new Intent(this, ForumSharingStatusActivity.class);
-				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-				i3.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i3);
-				return true;
-			case R.id.action_forum_delete:
-				showUnsubscribeDialog();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_forum_share) {
+			Intent i = new Intent(this, ShareForumActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_SHARE_FORUM);
+			return true;
+		} else if (itemId == R.id.action_forum_sharing_status) {
+			Intent i = new Intent(this, ForumSharingStatusActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_forum_delete) {
+			showUnsubscribeDialog();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
@@ -135,7 +127,7 @@ public class ForumActivity extends
 	}
 
 	private void showUnsubscribeDialog() {
-		OnClickListener okListener = (dialog, which) -> deleteForum();
+		OnClickListener okListener = (dialog, which) -> viewModel.deleteForum();
 		AlertDialog.Builder builder = new AlertDialog.Builder(this,
 				R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_leave_forum));
@@ -145,27 +137,4 @@ public class ForumActivity extends
 		builder.show();
 	}
 
-	private void deleteForum() {
-		forumController.deleteNamedGroup(
-				new UiResultExceptionHandler<Void, DbException>(this) {
-					@Override
-					public void onResultUi(Void v) {
-						Toast.makeText(ForumActivity.this,
-								R.string.forum_left_toast, LENGTH_SHORT).show();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	public void onForumLeft(ContactId c) {
-		sharingController.remove(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumController.java

@@ -1,18 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.forum.Forum;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-interface ForumController extends ThreadListController<Forum, ForumPostItem> {
-
-	interface ForumListener extends ThreadListListener<ForumPostItem> {
-		@UiThread
-		void onForumLeft(ContactId c);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumControllerImpl.java

@@ -1,185 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.forum.ForumController.ForumListener;
-import org.briarproject.briar.android.threaded.ThreadListControllerImpl;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.forum.Forum;
-import org.briarproject.briar.api.forum.ForumInvitationResponse;
-import org.briarproject.briar.api.forum.ForumManager;
-import org.briarproject.briar.api.forum.ForumPost;
-import org.briarproject.briar.api.forum.ForumPostHeader;
-import org.briarproject.briar.api.forum.ForumSharingManager;
-import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
-import org.briarproject.briar.api.sharing.event.ContactLeftShareableEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import static java.lang.Math.max;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@NotNullByDefault
-class ForumControllerImpl extends
-		ThreadListControllerImpl<Forum, ForumPostItem, ForumPostHeader, ForumPost, ForumListener>
-		implements ForumController {
-
-	private static final Logger LOG =
-			Logger.getLogger(ForumControllerImpl.class.getName());
-
-	private final ForumManager forumManager;
-	private final ForumSharingManager forumSharingManager;
-
-	@Inject
-	ForumControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, IdentityManager identityManager,
-			@CryptoExecutor Executor cryptoExecutor,
-			ForumManager forumManager, ForumSharingManager forumSharingManager,
-			EventBus eventBus, Clock clock, MessageTracker messageTracker,
-			AndroidNotificationManager notificationManager) {
-		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
-		this.forumManager = forumManager;
-		this.forumSharingManager = forumSharingManager;
-	}
-
-	@Override
-	public void onActivityStart() {
-		super.onActivityStart();
-		notificationManager.clearForumPostNotification(getGroupId());
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
-
-		if (e instanceof ForumPostReceivedEvent) {
-			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
-			if (f.getGroupId().equals(getGroupId())) {
-				LOG.info("Forum post received, adding...");
-				listener.onItemReceived(buildItem(f.getHeader(), f.getText()));
-			}
-		} else if (e instanceof ForumInvitationResponseReceivedEvent) {
-			ForumInvitationResponseReceivedEvent f =
-					(ForumInvitationResponseReceivedEvent) e;
-			ForumInvitationResponse r = f.getMessageHeader();
-			if (r.getShareableId().equals(getGroupId()) && r.wasAccepted()) {
-				LOG.info("Forum invitation was accepted");
-				listener.onInvitationAccepted(f.getContactId());
-			}
-		} else if (e instanceof ContactLeftShareableEvent) {
-			ContactLeftShareableEvent c = (ContactLeftShareableEvent) e;
-			if (c.getGroupId().equals(getGroupId())) {
-				LOG.info("Forum left by contact");
-				listener.onForumLeft(c.getContactId());
-			}
-		}
-	}
-
-	@Override
-	protected Forum loadNamedGroup() throws DbException {
-		return forumManager.getForum(getGroupId());
-	}
-
-	@Override
-	protected Collection<ForumPostHeader> loadHeaders() throws DbException {
-		return forumManager.getPostHeaders(getGroupId());
-	}
-
-	@Override
-	protected String loadMessageText(ForumPostHeader h) throws DbException {
-		return forumManager.getPostText(h.getId());
-	}
-
-	@Override
-	protected void markRead(MessageId id) throws DbException {
-		forumManager.setReadFlag(getGroupId(), id, true);
-	}
-
-	@Override
-	public void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				Collection<Contact> contacts =
-						forumSharingManager.getSharedWith(getGroupId());
-				Collection<ContactId> contactIds =
-						new ArrayList<>(contacts.size());
-				for (Contact c : contacts) contactIds.add(c.getId());
-				handler.onResult(contactIds);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void createAndStoreMessage(String text,
-			@Nullable ForumPostItem parentItem,
-			ResultExceptionHandler<ForumPostItem, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				GroupCount count = forumManager.getGroupCount(getGroupId());
-				long timestamp = max(count.getLatestMsgTime() + 1,
-						clock.currentTimeMillis());
-				MessageId parentId = parentItem != null ?
-						parentItem.getId() : null;
-				createMessage(text, timestamp, parentId, author, handler);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	private void createMessage(String text, long timestamp,
-			@Nullable MessageId parentId, LocalAuthor author,
-			ResultExceptionHandler<ForumPostItem, DbException> handler) {
-		cryptoExecutor.execute(() -> {
-			LOG.info("Creating forum post...");
-			ForumPost msg = forumManager.createLocalPost(getGroupId(), text,
-					timestamp, parentId, author);
-			storePost(msg, text, handler);
-		});
-	}
-
-	@Override
-	protected ForumPostHeader addLocalMessage(ForumPost p) throws DbException {
-		return forumManager.addLocalPost(p);
-	}
-
-	@Override
-	protected void deleteNamedGroup(Forum forum) throws DbException {
-		forumManager.removeForum(forum);
-	}
-
-	@Override
-	protected ForumPostItem buildItem(ForumPostHeader header, String text) {
-		return new ForumPostItem(header, text);
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumModule.java

@@ -1,32 +1,23 @@
 package org.briarproject.briar.android.forum;
 
-import org.briarproject.briar.android.activity.ActivityScope;
-import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
 import androidx.lifecycle.ViewModel;
 import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
 import dagger.multibindings.IntoMap;
 
 @Module
-public class ForumModule {
+public interface ForumModule {
 
-	@Module
-	public interface BindsModule {
-		@Binds
-		@IntoMap
-		@ViewModelKey(ForumListViewModel.class)
-		ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(ForumListViewModel.class)
+	ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
 
-	@ActivityScope
-	@Provides
-	ForumController provideForumController(BaseActivity activity,
-			ForumControllerImpl forumController) {
-		activity.addLifecycleController(forumController);
-		return forumController;
-	}
+	@Binds
+	@IntoMap
+	@ViewModelKey(ForumViewModel.class)
+	ViewModel bindForumViewModel(ForumViewModel forumViewModel);
 
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumPostItem.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.threaded.ThreadItem;
 import org.briarproject.briar.api.forum.ForumPostHeader;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
 @NotThreadSafe
@@ -17,9 +16,4 @@ class ForumPostItem extends ThreadItem {
 				h.getAuthorInfo(), h.isRead());
 	}
 
-	ForumPostItem(MessageId messageId, @Nullable MessageId parentId,
-			String text, long timestamp, Author author, AuthorInfo authorInfo) {
-		super(messageId, parentId, text, timestamp, author, authorInfo, true);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumViewModel.java

@@ -0,0 +1,231 @@
+package org.briarproject.briar.android.forum;
+
+import android.app.Application;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.forum.Forum;
+import org.briarproject.briar.api.forum.ForumInvitationResponse;
+import org.briarproject.briar.api.forum.ForumManager;
+import org.briarproject.briar.api.forum.ForumPost;
+import org.briarproject.briar.api.forum.ForumPostHeader;
+import org.briarproject.briar.api.forum.ForumSharingManager;
+import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
+import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
+import org.briarproject.briar.api.sharing.event.ContactLeftShareableEvent;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static android.widget.Toast.LENGTH_SHORT;
+import static java.lang.Math.max;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class ForumViewModel extends ThreadListViewModel<ForumPostItem> {
+
+	private static final Logger LOG = getLogger(ForumViewModel.class.getName());
+
+	private final ForumManager forumManager;
+	private final ForumSharingManager forumSharingManager;
+
+	@Inject
+	ForumViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			SharingController sharingController,
+			@CryptoExecutor Executor cryptoExecutor,
+			Clock clock,
+			MessageTracker messageTracker,
+			EventBus eventBus,
+			ForumManager forumManager,
+			ForumSharingManager forumSharingManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				identityManager, notificationManager, sharingController,
+				cryptoExecutor, clock, messageTracker, eventBus);
+		this.forumManager = forumManager;
+		this.forumSharingManager = forumSharingManager;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ForumPostReceivedEvent) {
+			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
+			if (f.getGroupId().equals(groupId)) {
+				LOG.info("Forum post received, adding...");
+				ForumPostItem item =
+						new ForumPostItem(f.getHeader(), f.getText());
+				addItem(item, false);
+			}
+		} else if (e instanceof ForumInvitationResponseReceivedEvent) {
+			ForumInvitationResponseReceivedEvent f =
+					(ForumInvitationResponseReceivedEvent) e;
+			ForumInvitationResponse r = f.getMessageHeader();
+			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
+				LOG.info("Forum invitation was accepted");
+				sharingController.add(f.getContactId());
+			}
+		} else if (e instanceof ContactLeftShareableEvent) {
+			ContactLeftShareableEvent c = (ContactLeftShareableEvent) e;
+			if (c.getGroupId().equals(groupId)) {
+				LOG.info("Forum left by contact");
+				sharingController.remove(c.getContactId());
+			}
+		} else {
+			super.eventOccurred(e);
+		}
+	}
+
+	protected void clearNotifications() {
+		notificationManager.clearForumPostNotification(groupId);
+	}
+
+	LiveData<Forum> loadForum() {
+		MutableLiveData<Forum> forum = new MutableLiveData<>();
+		runOnDbThread(() -> {
+			try {
+				Forum f = forumManager.getForum(groupId);
+				forum.postValue(f);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+		return forum;
+	}
+
+	@Override
+	public void loadItems() {
+		loadList(txn -> {
+			long start = now();
+			List<ForumPostHeader> headers =
+					forumManager.getPostHeaders(txn, groupId);
+			logDuration(LOG, "Loading headers", start);
+			start = now();
+			List<ForumPostItem> items = new ArrayList<>();
+			for (ForumPostHeader header : headers) {
+				items.add(loadItem(txn, header));
+			}
+			logDuration(LOG, "Loading bodies and creating items", start);
+			return items;
+		}, this::setItems);
+	}
+
+	private ForumPostItem loadItem(Transaction txn, ForumPostHeader header)
+			throws DbException {
+		String text = forumManager.getPostText(txn, header.getId());
+		return new ForumPostItem(header, text);
+	}
+
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable MessageId parentId) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				GroupCount count = forumManager.getGroupCount(groupId);
+				long timestamp = max(count.getLatestMsgTime() + 1,
+						clock.currentTimeMillis());
+				createMessage(text, timestamp, parentId, author);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void createMessage(String text, long timestamp,
+			@Nullable MessageId parentId, LocalAuthor author) {
+		cryptoExecutor.execute(() -> {
+			LOG.info("Creating forum post...");
+			ForumPost msg = forumManager.createLocalPost(groupId, text,
+					timestamp, parentId, author);
+			storePost(msg, text);
+		});
+	}
+
+	private void storePost(ForumPost msg, String text) {
+		runOnDbThread(false, txn -> {
+			long start = now();
+			ForumPostHeader header = forumManager.addLocalPost(txn, msg);
+			logDuration(LOG, "Storing forum post", start);
+			txn.attach(() -> {
+				ForumPostItem item = new ForumPostItem(header, text);
+				addItem(item, true);
+			});
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	@Override
+	protected void markItemRead(ForumPostItem item) {
+		runOnDbThread(() -> {
+			try {
+				forumManager.setReadFlag(groupId, item.getId(), true);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	public void loadSharingContacts() {
+		runOnDbThread(true, txn -> {
+			Collection<Contact> contacts =
+					forumSharingManager.getSharedWith(txn, groupId);
+			Collection<ContactId> contactIds = new ArrayList<>(contacts.size());
+			for (Contact c : contacts) contactIds.add(c.getId());
+			txn.attach(() -> sharingController.addAll(contactIds));
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	void deleteForum() {
+		runOnDbThread(() -> {
+			try {
+				Forum f = forumManager.getForum(groupId);
+				forumManager.removeForum(f);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+		Toast.makeText(getApplication(), R.string.forum_left_toast,
+				LENGTH_SHORT).show();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupActivity.java

@@ -1,67 +1,60 @@
 package org.briarproject.briar.android.privategroup.conversation;
 
-import android.content.DialogInterface;
-import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.android.privategroup.conversation.GroupController.GroupListener;
 import org.briarproject.briar.android.privategroup.creation.GroupInviteActivity;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberListActivity;
 import org.briarproject.briar.android.privategroup.reveal.RevealContactsActivity;
 import org.briarproject.briar.android.threaded.ThreadListActivity;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.Visibility;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.widget.Toolbar;
-import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_GROUP_INVITE;
+import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 import static org.briarproject.briar.api.privategroup.PrivateGroupConstants.MAX_GROUP_POST_TEXT_LENGTH;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class GroupActivity extends
-		ThreadListActivity<PrivateGroup, GroupMessageItem, GroupMessageAdapter>
-		implements GroupListener, OnClickListener {
+		ThreadListActivity<GroupMessageItem, GroupMessageAdapter> {
 
 	@Inject
-	GroupController controller;
+	ViewModelProvider.Factory viewModelFactory;
 
-	@Nullable
-	private Boolean isCreator = null;
-	private boolean isDissolved = false;
-	private MenuItem revealMenuItem, inviteMenuItem, leaveMenuItem,
-			dissolveMenuItem;
+	private GroupViewModel viewModel;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(GroupViewModel.class);
 	}
 
 	@Override
-	protected ThreadListController<PrivateGroup, GroupMessageItem> getController() {
-		return controller;
+	protected ThreadListViewModel<GroupMessageItem> getViewModel() {
+		return viewModel;
+	}
+
+	@Override
+	protected GroupMessageAdapter createAdapter() {
+		return new GroupMessageAdapter(this);
 	}
 
 	@Override
@@ -69,65 +62,27 @@ public class GroupActivity extends
 		super.onCreate(state);
 
 		Toolbar toolbar = setUpCustomToolbar(false);
-
-		Intent i = getIntent();
-		String groupName = i.getStringExtra(GROUP_NAME);
-		if (groupName != null) setTitle(groupName);
-		loadNamedGroup();
-
 		// Open member list on Toolbar click
-		if (toolbar != null) {
-			toolbar.setOnClickListener(v -> {
-				Intent i1 = new Intent(GroupActivity.this,
-						GroupMemberListActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-			});
-		}
+		toolbar.setOnClickListener(v -> {
+			Intent i = new Intent(GroupActivity.this,
+					GroupMemberListActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+		});
 
+		String groupName = getIntent().getStringExtra(GROUP_NAME);
+		if (groupName != null) setTitle(groupName);
+		observeOnce(viewModel.getPrivateGroup(), this, privateGroup ->
+				setTitle(privateGroup.getName())
+		);
+		observeOnce(viewModel.isCreator(), this, adapter::setIsCreator);
+
+		// start with group disabled and enable when not dissolved
 		setGroupEnabled(false);
-	}
-
-	@Override
-	protected GroupMessageAdapter createAdapter(
-			LinearLayoutManager layoutManager) {
-		return new GroupMessageAdapter(this, layoutManager);
-	}
-
-	@Override
-	protected void loadItems() {
-		controller.isDissolved(
-				new UiResultExceptionHandler<Boolean, DbException>(this) {
-					@Override
-					public void onResultUi(Boolean isDissolved) {
-						setGroupEnabled(!isDissolved);
-						GroupActivity.super.loadItems();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@Override
-	protected void onNamedGroupLoaded(PrivateGroup group) {
-		setTitle(group.getName());
-		controller.loadLocalAuthor(
-				new UiResultExceptionHandler<LocalAuthor, DbException>(this) {
-					@Override
-					public void onResultUi(LocalAuthor author) {
-						isCreator = group.getCreator().equals(author);
-						adapter.setPerspective(isCreator);
-						showMenuItems();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.isDissolved().observeEvent(this, dissolved -> {
+			setGroupEnabled(!dissolved);
+			if (dissolved) onGroupDissolved();
+		});
 	}
 
 	@Override
@@ -136,74 +91,61 @@ public class GroupActivity extends
 		MenuInflater inflater = getMenuInflater();
 		inflater.inflate(R.menu.group_actions, menu);
 
-		revealMenuItem = menu.findItem(R.id.action_group_reveal);
-		inviteMenuItem = menu.findItem(R.id.action_group_invite);
-		leaveMenuItem = menu.findItem(R.id.action_group_leave);
-		dissolveMenuItem = menu.findItem(R.id.action_group_dissolve);
-
-		// all role-dependent items are invisible until we know our role
-		revealMenuItem.setVisible(false);
-		inviteMenuItem.setVisible(false);
-		leaveMenuItem.setVisible(false);
-		dissolveMenuItem.setVisible(false);
-
-		// show items based on role
-		showMenuItems();
-
-		return super.onCreateOptionsMenu(menu);
+		// show items based on role (which will not change, so observe once)
+		observeOnce(viewModel.isCreator(), this, isCreator -> {
+			menu.findItem(R.id.action_group_reveal).setVisible(!isCreator);
+			menu.findItem(R.id.action_group_invite).setVisible(isCreator);
+			menu.findItem(R.id.action_group_leave).setVisible(!isCreator);
+			menu.findItem(R.id.action_group_dissolve).setVisible(isCreator);
+		});
+		super.onCreateOptionsMenu(menu);
+		return true;
 	}
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case R.id.action_group_member_list:
-				Intent i1 = new Intent(this, GroupMemberListActivity.class);
-				i1.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i1);
-				return true;
-			case R.id.action_group_reveal:
-				if (isCreator == null || isCreator)
-					throw new IllegalStateException();
-				Intent i2 = new Intent(this, RevealContactsActivity.class);
-				i2.putExtra(GROUP_ID, groupId.getBytes());
-				startActivity(i2);
-				return true;
-			case R.id.action_group_invite:
-				if (isCreator == null || !isCreator)
-					throw new IllegalStateException();
-				Intent i3 = new Intent(this, GroupInviteActivity.class);
-				i3.putExtra(GROUP_ID, groupId.getBytes());
-				startActivityForResult(i3, REQUEST_GROUP_INVITE);
-				return true;
-			case R.id.action_group_leave:
-				if (isCreator == null || isCreator)
-					throw new IllegalStateException();
-				showLeaveGroupDialog();
-				return true;
-			case R.id.action_group_dissolve:
-				if (isCreator == null || !isCreator)
-					throw new IllegalStateException();
-				showDissolveGroupDialog();
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_group_member_list) {
+			Intent i = new Intent(this, GroupMemberListActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_group_reveal) {
+			if (requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			Intent i = new Intent(this, RevealContactsActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_group_invite) {
+			if (!requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			Intent i = new Intent(this, GroupInviteActivity.class);
+			i.putExtra(GROUP_ID, groupId.getBytes());
+			startActivityForResult(i, REQUEST_GROUP_INVITE);
+			return true;
+		} else if (itemId == R.id.action_group_leave) {
+			if (requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			showLeaveGroupDialog();
+			return true;
+		} else if (itemId == R.id.action_group_dissolve) {
+			if (!requireNonNull(viewModel.isCreator().getValue()))
+				throw new IllegalStateException();
+			showDissolveGroupDialog();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
-	protected void onActivityResult(int request, int result, Intent data) {
+	protected void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		if (request == REQUEST_GROUP_INVITE && result == RESULT_OK) {
 			displaySnackbar(R.string.groups_invitation_sent);
 		} else super.onActivityResult(request, result, data);
 	}
 
-	@Override
-	public void onItemReceived(GroupMessageItem item) {
-		super.onItemReceived(item);
-		if (item instanceof JoinMessageItem) {
-			if (((JoinMessageItem) item).isInitial()) loadSharingContacts();
-		}
-	}
-
 	@Override
 	protected int getMaxTextLength() {
 		return MAX_GROUP_POST_TEXT_LENGTH;
@@ -211,11 +153,11 @@ public class GroupActivity extends
 
 	@Override
 	public void onReplyClick(GroupMessageItem item) {
-		if (!isDissolved) super.onReplyClick(item);
+		Boolean isDissolved = viewModel.isDissolved().getLastValue();
+		if (isDissolved != null && !isDissolved) super.onReplyClick(item);
 	}
 
 	private void setGroupEnabled(boolean enabled) {
-		isDissolved = !enabled;
 		sendController.setReady(enabled);
 		list.getRecyclerView().setAlpha(enabled ? 1f : 0.5f);
 
@@ -227,21 +169,13 @@ public class GroupActivity extends
 		}
 	}
 
-	private void showMenuItems() {
-		// we need to have the menu items and know if we are the creator
-		if (leaveMenuItem == null || isCreator == null) return;
-		revealMenuItem.setVisible(!isCreator);
-		inviteMenuItem.setVisible(isCreator);
-		leaveMenuItem.setVisible(!isCreator);
-		dissolveMenuItem.setVisible(isCreator);
-	}
-
 	private void showLeaveGroupDialog() {
 		AlertDialog.Builder builder =
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_leave_dialog_title));
 		builder.setMessage(getString(R.string.groups_leave_dialog_message));
-		builder.setNegativeButton(R.string.dialog_button_leave, this);
+		builder.setNegativeButton(R.string.dialog_button_leave,
+				(d, w) -> deleteGroup());
 		builder.setPositiveButton(R.string.cancel, null);
 		builder.show();
 	}
@@ -251,37 +185,19 @@ public class GroupActivity extends
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_dissolve_dialog_title));
 		builder.setMessage(getString(R.string.groups_dissolve_dialog_message));
-		builder.setNegativeButton(R.string.groups_dissolve_button, this);
+		builder.setNegativeButton(R.string.groups_dissolve_button,
+				(d, w) -> deleteGroup());
 		builder.setPositiveButton(R.string.cancel, null);
 		builder.show();
 	}
 
-	@Override
-	public void onClick(DialogInterface dialog, int which) {
-		controller.deleteNamedGroup(
-				new UiExceptionHandler<DbException>(this) {
-					// The activity is going to be destroyed by the
-					// GroupRemovedEvent being fired
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+	private void deleteGroup() {
+		// The activity is going to be destroyed by the
+		// GroupRemovedEvent being fired
+		viewModel.deletePrivateGroup();
 	}
 
-	@Override
-	public void onContactRelationshipRevealed(AuthorId memberId, ContactId c,
-			Visibility v) {
-		adapter.updateVisibility(memberId, v);
-
-		sharingController.add(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
-	@Override
-	public void onGroupDissolved() {
-		setGroupEnabled(false);
+	private void onGroupDissolved() {
 		AlertDialog.Builder builder =
 				new AlertDialog.Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.groups_dissolved_dialog_title));

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupController.java

@@ -1,33 +0,0 @@
-package org.briarproject.briar.android.privategroup.conversation;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.AuthorId;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.threaded.ThreadListController;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.Visibility;
-
-import androidx.annotation.UiThread;
-
-public interface GroupController
-		extends ThreadListController<PrivateGroup, GroupMessageItem> {
-
-	void loadLocalAuthor(
-			ResultExceptionHandler<LocalAuthor, DbException> handler);
-
-	void isDissolved(
-			ResultExceptionHandler<Boolean, DbException> handler);
-
-	interface GroupListener extends ThreadListListener<GroupMessageItem> {
-
-		@UiThread
-		void onContactRelationshipRevealed(AuthorId memberId,
-				ContactId contactId, Visibility v);
-
-		@UiThread
-		void onGroupDissolved();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupControllerImpl.java

@@ -1,242 +0,0 @@
-package org.briarproject.briar.android.privategroup.conversation;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.identity.LocalAuthor;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.privategroup.conversation.GroupController.GroupListener;
-import org.briarproject.briar.android.threaded.ThreadListControllerImpl;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.privategroup.GroupMember;
-import org.briarproject.briar.api.privategroup.GroupMessage;
-import org.briarproject.briar.api.privategroup.GroupMessageFactory;
-import org.briarproject.briar.api.privategroup.GroupMessageHeader;
-import org.briarproject.briar.api.privategroup.JoinMessageHeader;
-import org.briarproject.briar.api.privategroup.PrivateGroup;
-import org.briarproject.briar.api.privategroup.PrivateGroupManager;
-import org.briarproject.briar.api.privategroup.event.ContactRelationshipRevealedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupDissolvedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupInvitationResponseReceivedEvent;
-import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
-import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import static java.lang.Math.max;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-class GroupControllerImpl extends
-		ThreadListControllerImpl<PrivateGroup, GroupMessageItem, GroupMessageHeader, GroupMessage, GroupListener>
-		implements GroupController {
-
-	private static final Logger LOG =
-			Logger.getLogger(GroupControllerImpl.class.getName());
-
-	private final PrivateGroupManager privateGroupManager;
-	private final GroupMessageFactory groupMessageFactory;
-
-	@Inject
-	GroupControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, IdentityManager identityManager,
-			@CryptoExecutor Executor cryptoExecutor,
-			PrivateGroupManager privateGroupManager,
-			GroupMessageFactory groupMessageFactory, EventBus eventBus,
-			MessageTracker messageTracker, Clock clock,
-			AndroidNotificationManager notificationManager) {
-		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
-		this.privateGroupManager = privateGroupManager;
-		this.groupMessageFactory = groupMessageFactory;
-	}
-
-	@Override
-	public void onActivityStart() {
-		super.onActivityStart();
-		notificationManager.clearGroupMessageNotification(getGroupId());
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
-
-		if (e instanceof GroupMessageAddedEvent) {
-			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
-			if (!g.isLocal() && g.getGroupId().equals(getGroupId())) {
-				LOG.info("Group message received, adding...");
-				listener.onItemReceived(buildItem(g.getHeader(), g.getText()));
-			}
-		} else if (e instanceof ContactRelationshipRevealedEvent) {
-			ContactRelationshipRevealedEvent c =
-					(ContactRelationshipRevealedEvent) e;
-			if (getGroupId().equals(c.getGroupId())) {
-				listener.onContactRelationshipRevealed(c.getMemberId(),
-						c.getContactId(), c.getVisibility());
-			}
-		} else if (e instanceof GroupInvitationResponseReceivedEvent) {
-			GroupInvitationResponseReceivedEvent g =
-					(GroupInvitationResponseReceivedEvent) e;
-			GroupInvitationResponse r = g.getMessageHeader();
-			if (getGroupId().equals(r.getShareableId()) && r.wasAccepted()) {
-				listener.onInvitationAccepted(g.getContactId());
-			}
-		} else if (e instanceof GroupDissolvedEvent) {
-			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
-			if (getGroupId().equals(g.getGroupId())) {
-				listener.onGroupDissolved();
-			}
-		}
-	}
-
-	@Override
-	protected PrivateGroup loadNamedGroup() throws DbException {
-		return privateGroupManager.getPrivateGroup(getGroupId());
-	}
-
-	@Override
-	protected Collection<GroupMessageHeader> loadHeaders() throws DbException {
-		return privateGroupManager.getHeaders(getGroupId());
-	}
-
-	@Override
-	protected String loadMessageText(GroupMessageHeader header)
-			throws DbException {
-		if (header instanceof JoinMessageHeader) {
-			// will be looked up later
-			return "";
-		}
-		return privateGroupManager.getMessageText(header.getId());
-	}
-
-	@Override
-	protected void markRead(MessageId id) throws DbException {
-		privateGroupManager.setReadFlag(getGroupId(), id, true);
-	}
-
-	@Override
-	public void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				Collection<GroupMember> members =
-						privateGroupManager.getMembers(getGroupId());
-				Collection<ContactId> contactIds = new ArrayList<>();
-				for (GroupMember m : members) {
-					if (m.getContactId() != null)
-						contactIds.add(m.getContactId());
-				}
-				handler.onResult(contactIds);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void createAndStoreMessage(String text,
-			@Nullable GroupMessageItem parentItem,
-			ResultExceptionHandler<GroupMessageItem, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				MessageId parentId = null;
-				MessageId previousMsgId =
-						privateGroupManager.getPreviousMsgId(getGroupId());
-				GroupCount count =
-						privateGroupManager.getGroupCount(getGroupId());
-				long timestamp = count.getLatestMsgTime();
-				if (parentItem != null) parentId = parentItem.getId();
-				timestamp = max(clock.currentTimeMillis(), timestamp + 1);
-				createMessage(text, timestamp, parentId, author, previousMsgId,
-						handler);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	private void createMessage(String text, long timestamp,
-			@Nullable MessageId parentId, LocalAuthor author,
-			MessageId previousMsgId,
-			ResultExceptionHandler<GroupMessageItem, DbException> handler) {
-		cryptoExecutor.execute(() -> {
-			LOG.info("Creating group message...");
-			GroupMessage msg = groupMessageFactory
-					.createGroupMessage(getGroupId(), timestamp,
-							parentId, author, text, previousMsgId);
-			storePost(msg, text, handler);
-		});
-	}
-
-	@Override
-	protected GroupMessageHeader addLocalMessage(GroupMessage message)
-			throws DbException {
-		return privateGroupManager.addLocalMessage(message);
-	}
-
-	@Override
-	protected void deleteNamedGroup(PrivateGroup group) throws DbException {
-		privateGroupManager.removePrivateGroup(group.getId());
-	}
-
-	@Override
-	protected GroupMessageItem buildItem(GroupMessageHeader header,
-			String text) {
-		if (header instanceof JoinMessageHeader) {
-			return new JoinMessageItem((JoinMessageHeader) header, text);
-		}
-		return new GroupMessageItem(header, text);
-	}
-
-	@Override
-	public void loadLocalAuthor(
-			ResultExceptionHandler<LocalAuthor, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				LocalAuthor author = identityManager.getLocalAuthor();
-				handler.onResult(author);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void isDissolved(
-			ResultExceptionHandler<Boolean, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				boolean isDissolved =
-						privateGroupManager.isDissolved(getGroupId());
-				handler.onResult(isDissolved);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupConversationModule.java

@@ -1,19 +1,18 @@
 package org.briarproject.briar.android.privategroup.conversation;
 
-import org.briarproject.briar.android.activity.ActivityScope;
-import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
 import dagger.Module;
-import dagger.Provides;
+import dagger.multibindings.IntoMap;
 
 @Module
-public class GroupConversationModule {
+public interface GroupConversationModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(GroupViewModel.class)
+	ViewModel bindGroupViewModel(GroupViewModel groupViewModel);
 
-	@ActivityScope
-	@Provides
-	GroupController provideGroupController(BaseActivity activity,
-			GroupControllerImpl groupController) {
-		activity.addLifecycleController(groupController);
-		return groupController;
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupMessageAdapter.java

@@ -4,19 +4,14 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
-import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.threaded.BaseThreadItemViewHolder;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter;
 import org.briarproject.briar.android.threaded.ThreadPostViewHolder;
-import org.briarproject.briar.api.privategroup.Visibility;
 
 import androidx.annotation.LayoutRes;
 import androidx.annotation.UiThread;
-import androidx.recyclerview.widget.LinearLayoutManager;
-
-import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
 
 @UiThread
 @NotNullByDefault
@@ -24,15 +19,14 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 
 	private boolean isCreator = false;
 
-	GroupMessageAdapter(ThreadItemListener<GroupMessageItem> listener,
-			LinearLayoutManager layoutManager) {
-		super(listener, layoutManager);
+	GroupMessageAdapter(ThreadItemListener<GroupMessageItem> listener) {
+		super(listener);
 	}
 
 	@LayoutRes
 	@Override
 	public int getItemViewType(int position) {
-		GroupMessageItem item = items.get(position);
+		GroupMessageItem item = getItem(position);
 		return item.getLayout();
 	}
 
@@ -47,30 +41,9 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 		return new ThreadPostViewHolder<>(v);
 	}
 
-	void setPerspective(boolean isCreator) {
+	void setIsCreator(boolean isCreator) {
 		this.isCreator = isCreator;
 		notifyDataSetChanged();
 	}
 
-	void updateVisibility(AuthorId memberId, Visibility v) {
-		int position = findItemPosition(memberId);
-		if (position != NO_POSITION) {
-			GroupMessageItem item = items.get(position);
-			if (item instanceof JoinMessageItem) {
-				((JoinMessageItem) item).setVisibility(v);
-				notifyItemChanged(findItemPosition(item), item);
-			}
-		}
-	}
-
-	private int findItemPosition(AuthorId a) {
-		int count = items.size();
-		for (int i = 0; i < count; i++) {
-			GroupMessageItem item = items.get(i);
-			if (item.getAuthor().getId().equals(a))
-				return i;
-		}
-		return NO_POSITION; // Not found
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupViewModel.java

@@ -0,0 +1,289 @@
+package org.briarproject.briar.android.privategroup.conversation;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.threaded.ThreadListViewModel;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.privategroup.GroupMember;
+import org.briarproject.briar.api.privategroup.GroupMessage;
+import org.briarproject.briar.api.privategroup.GroupMessageFactory;
+import org.briarproject.briar.api.privategroup.GroupMessageHeader;
+import org.briarproject.briar.api.privategroup.JoinMessageHeader;
+import org.briarproject.briar.api.privategroup.PrivateGroup;
+import org.briarproject.briar.api.privategroup.PrivateGroupManager;
+import org.briarproject.briar.api.privategroup.event.ContactRelationshipRevealedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupDissolvedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupInvitationResponseReceivedEvent;
+import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
+import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.lang.Math.max;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
+
+	private static final Logger LOG = getLogger(GroupViewModel.class.getName());
+
+	private final PrivateGroupManager privateGroupManager;
+	private final GroupMessageFactory groupMessageFactory;
+
+	private final MutableLiveData<PrivateGroup> privateGroup =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> isCreator = new MutableLiveData<>();
+	private final MutableLiveEvent<Boolean> isDissolved =
+			new MutableLiveEvent<>();
+
+	@Inject
+	GroupViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			SharingController sharingController,
+			@CryptoExecutor Executor cryptoExecutor,
+			Clock clock,
+			MessageTracker messageTracker,
+			PrivateGroupManager privateGroupManager,
+			GroupMessageFactory groupMessageFactory) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				identityManager, notificationManager, sharingController,
+				cryptoExecutor, clock, messageTracker, eventBus);
+		this.privateGroupManager = privateGroupManager;
+		this.groupMessageFactory = groupMessageFactory;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof GroupMessageAddedEvent) {
+			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
+			// only act on non-local messages in this group
+			if (!g.isLocal() && g.getGroupId().equals(groupId)) {
+				LOG.info("Group message received, adding...");
+				GroupMessageItem item = buildItem(g.getHeader(), g.getText());
+				addItem(item, false);
+				// In case the join message comes from the creator,
+				// we need to reload the sharing contacts
+				// in case it was delayed and the sharing count is wrong (#850).
+				if (item instanceof JoinMessageItem &&
+						(((JoinMessageItem) item).isInitial())) {
+					loadSharingContacts();
+				}
+			}
+		} else if (e instanceof GroupInvitationResponseReceivedEvent) {
+			GroupInvitationResponseReceivedEvent g =
+					(GroupInvitationResponseReceivedEvent) e;
+			GroupInvitationResponse r = g.getMessageHeader();
+			if (r.getShareableId().equals(groupId) && r.wasAccepted()) {
+				sharingController.add(g.getContactId());
+			}
+		} else if (e instanceof ContactRelationshipRevealedEvent) {
+			ContactRelationshipRevealedEvent c =
+					(ContactRelationshipRevealedEvent) e;
+			if (c.getGroupId().equals(groupId)) {
+				sharingController.add(c.getContactId());
+			}
+		} else if (e instanceof GroupDissolvedEvent) {
+			GroupDissolvedEvent g = (GroupDissolvedEvent) e;
+			if (g.getGroupId().equals(groupId)) {
+				isDissolved.setEvent(true);
+			}
+		} else {
+			super.eventOccurred(e);
+		}
+	}
+
+	@Override
+	protected void performInitialLoad() {
+		super.performInitialLoad();
+		loadPrivateGroup(groupId);
+	}
+
+	protected void clearNotifications() {
+		notificationManager.clearGroupMessageNotification(groupId);
+	}
+
+	private void loadPrivateGroup(GroupId groupId) {
+		runOnDbThread(() -> {
+			try {
+				PrivateGroup g = privateGroupManager.getPrivateGroup(groupId);
+				privateGroup.postValue(g);
+				Author author = identityManager.getLocalAuthor();
+				isCreator.postValue(g.getCreator().equals(author));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@Override
+	public void loadItems() {
+		loadList(txn -> {
+			// check first if group is dissolved
+			isDissolved
+					.postEvent(privateGroupManager.isDissolved(txn, groupId));
+			// now continue to load the items
+			long start = now();
+			List<GroupMessageHeader> headers =
+					privateGroupManager.getHeaders(txn, groupId);
+			logDuration(LOG, "Loading headers", start);
+			start = now();
+			List<GroupMessageItem> items = new ArrayList<>();
+			for (GroupMessageHeader header : headers) {
+				items.add(loadItem(txn, header));
+			}
+			logDuration(LOG, "Loading bodies and creating items", start);
+			return items;
+		}, this::setItems);
+	}
+
+	private GroupMessageItem loadItem(Transaction txn,
+			GroupMessageHeader header) throws DbException {
+		String text;
+		if (header instanceof JoinMessageHeader) {
+			// will be looked up later
+			text = "";
+		} else {
+			text = privateGroupManager.getMessageText(txn, header.getId());
+		}
+		return buildItem(header, text);
+	}
+
+	private GroupMessageItem buildItem(GroupMessageHeader header, String text) {
+		if (header instanceof JoinMessageHeader) {
+			return new JoinMessageItem((JoinMessageHeader) header, text);
+		}
+		return new GroupMessageItem(header, text);
+	}
+
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable MessageId parentId) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				MessageId previousMsgId =
+						privateGroupManager.getPreviousMsgId(groupId);
+				GroupCount count = privateGroupManager.getGroupCount(groupId);
+				long timestamp = count.getLatestMsgTime();
+				timestamp = max(clock.currentTimeMillis(), timestamp + 1);
+				createMessage(text, timestamp, parentId, author, previousMsgId);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void createMessage(String text, long timestamp,
+			@Nullable MessageId parentId, LocalAuthor author,
+			MessageId previousMsgId) {
+		cryptoExecutor.execute(() -> {
+			LOG.info("Creating group message...");
+			GroupMessage msg = groupMessageFactory.createGroupMessage(groupId,
+					timestamp, parentId, author, text, previousMsgId);
+			storePost(msg, text);
+		});
+	}
+
+	private void storePost(GroupMessage msg, String text) {
+		runOnDbThread(false, txn -> {
+			long start = now();
+			GroupMessageHeader header =
+					privateGroupManager.addLocalMessage(txn, msg);
+			logDuration(LOG, "Storing group message", start);
+			txn.attach(() ->
+					addItem(buildItem(header, text), true)
+			);
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	@Override
+	protected void markItemRead(GroupMessageItem item) {
+		runOnDbThread(() -> {
+			try {
+				privateGroupManager.setReadFlag(groupId, item.getId(), true);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	public void loadSharingContacts() {
+		runOnDbThread(true, txn -> {
+			Collection<GroupMember> members =
+					privateGroupManager.getMembers(txn, groupId);
+			Collection<ContactId> contactIds = new ArrayList<>();
+			for (GroupMember m : members) {
+				if (m.getContactId() != null)
+					contactIds.add(m.getContactId());
+			}
+			txn.attach(() -> sharingController.addAll(contactIds));
+		}, e -> logException(LOG, WARNING, e));
+	}
+
+	void deletePrivateGroup() {
+		runOnDbThread(() -> {
+			try {
+				privateGroupManager.removePrivateGroup(groupId);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<PrivateGroup> getPrivateGroup() {
+		return privateGroup;
+	}
+
+	LiveData<Boolean> isCreator() {
+		return isCreator;
+	}
+
+	LiveEvent<Boolean> isDissolved() {
+		return isDissolved;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/JoinMessageItem.java

@@ -2,7 +2,6 @@ package org.briarproject.briar.android.privategroup.conversation;
 
 import org.briarproject.briar.R;
 import org.briarproject.briar.api.privategroup.JoinMessageHeader;
-import org.briarproject.briar.api.privategroup.Visibility;
 
 import javax.annotation.concurrent.NotThreadSafe;
 
@@ -13,13 +12,11 @@ import androidx.annotation.UiThread;
 @NotThreadSafe
 class JoinMessageItem extends GroupMessageItem {
 
-	private Visibility visibility;
 	private final boolean isInitial;
 
 	JoinMessageItem(JoinMessageHeader h, String text) {
 		super(h, text);
-		this.visibility = h.getVisibility();
-		this.isInitial = h.isInitial();
+		isInitial = h.isInitial();
 	}
 
 	@Override
@@ -33,14 +30,6 @@ class JoinMessageItem extends GroupMessageItem {
 		return R.layout.list_item_group_join_notice;
 	}
 
-	Visibility getVisibility() {
-		return visibility;
-	}
-
-	void setVisibility(Visibility visibility) {
-		this.visibility = visibility;
-	}
-
 	boolean isInitial() {
 		return isInitial;
 	}

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingController.java

@@ -0,0 +1,54 @@
+package org.briarproject.briar.android.sharing;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+
+@NotNullByDefault
+public interface SharingController {
+
+	/**
+	 * Call this when the owning ViewModel gets cleared,
+	 * so the {@link EventBus} can get unregistered.
+	 */
+	void onCleared();
+
+	/**
+	 * Adds one contact to be tracked.
+	 */
+	@UiThread
+	void add(ContactId c);
+
+	/**
+	 * Adds a collection of contacts to be tracked.
+	 */
+	@UiThread
+	void addAll(Collection<ContactId> contacts);
+
+	/**
+	 * Call this when the contact identified by c is no longer sharing
+	 * the given group identified by GroupId g.
+	 */
+	@UiThread
+	void remove(ContactId c);
+
+	/**
+	 * Returns the total number of contacts that have been added.
+	 */
+	LiveData<SharingInfo> getSharingInfo();
+
+	class SharingInfo {
+		public final int total, online;
+
+		SharingInfo(int total, int online) {
+			this.total = total;
+			this.online = online;
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingControllerImpl.java

@@ -0,0 +1,102 @@
+package org.briarproject.briar.android.sharing;
+
+import org.briarproject.bramble.api.connection.ConnectionRegistry;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
+import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+@NotNullByDefault
+public class SharingControllerImpl implements SharingController, EventListener {
+
+	private final EventBus eventBus;
+	private final ConnectionRegistry connectionRegistry;
+
+	// UI thread
+	private final Set<ContactId> contacts = new HashSet<>();
+	private final MutableLiveData<SharingInfo> sharingInfo =
+			new MutableLiveData<>();
+
+	@Inject
+	SharingControllerImpl(EventBus eventBus,
+			ConnectionRegistry connectionRegistry) {
+		this.eventBus = eventBus;
+		this.connectionRegistry = connectionRegistry;
+		eventBus.addListener(this);
+	}
+
+	@Override
+	public void onCleared() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactConnectedEvent) {
+			setConnected(((ContactConnectedEvent) e).getContactId());
+		} else if (e instanceof ContactDisconnectedEvent) {
+			setConnected(((ContactDisconnectedEvent) e).getContactId());
+		}
+	}
+
+	@UiThread
+	private void setConnected(ContactId c) {
+		if (contacts.contains(c)) {
+			updateLiveData();
+		}
+	}
+
+	@UiThread
+	private void updateLiveData() {
+		int online = getOnlineCount();
+		sharingInfo.setValue(new SharingInfo(contacts.size(), online));
+	}
+
+	private int getOnlineCount() {
+		int online = 0;
+		for (ContactId c : contacts) {
+			if (connectionRegistry.isConnected(c)) online++;
+		}
+		return online;
+	}
+
+	@UiThread
+	@Override
+	public void addAll(Collection<ContactId> c) {
+		contacts.addAll(c);
+		updateLiveData();
+	}
+
+	@UiThread
+	@Override
+	public void add(ContactId c) {
+		contacts.add(c);
+		updateLiveData();
+	}
+
+	@UiThread
+	@Override
+	public void remove(ContactId c) {
+		contacts.remove(c);
+		updateLiveData();
+	}
+
+	@Override
+	public LiveData<SharingInfo> getSharingInfo() {
+		return sharingInfo;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingModule.java

@@ -9,36 +9,47 @@ import dagger.Provides;
 @Module
 public class SharingModule {
 
-	@ActivityScope
-	@Provides
-	ShareForumController provideShareForumController(
-			ShareForumControllerImpl shareForumController) {
-		return shareForumController;
+	@Module
+	@Deprecated
+	public static class SharingLegacyModule {
+
+		@ActivityScope
+		@Provides
+		ShareForumController provideShareForumController(
+				ShareForumControllerImpl shareForumController) {
+			return shareForumController;
+		}
+
+		@ActivityScope
+		@Provides
+		BlogInvitationController provideInvitationBlogController(
+				BaseActivity activity,
+				BlogInvitationControllerImpl blogInvitationController) {
+			activity.addLifecycleController(blogInvitationController);
+			return blogInvitationController;
+		}
+
+		@ActivityScope
+		@Provides
+		ForumInvitationController provideInvitationForumController(
+				BaseActivity activity,
+				ForumInvitationControllerImpl forumInvitationController) {
+			activity.addLifecycleController(forumInvitationController);
+			return forumInvitationController;
+		}
+
+		@ActivityScope
+		@Provides
+		ShareBlogController provideShareBlogController(
+				ShareBlogControllerImpl shareBlogController) {
+			return shareBlogController;
+		}
 	}
 
-	@ActivityScope
 	@Provides
-	BlogInvitationController provideInvitationBlogController(
-			BaseActivity activity,
-			BlogInvitationControllerImpl blogInvitationController) {
-		activity.addLifecycleController(blogInvitationController);
-		return blogInvitationController;
-	}
-
-	@ActivityScope
-	@Provides
-	ForumInvitationController provideInvitationForumController(
-			BaseActivity activity,
-			ForumInvitationControllerImpl forumInvitationController) {
-		activity.addLifecycleController(forumInvitationController);
-		return forumInvitationController;
-	}
-
-	@ActivityScope
-	@Provides
-	ShareBlogController provideShareBlogController(
-			ShareBlogControllerImpl shareBlogController) {
-		return shareBlogController;
+	SharingController provideSharingController(
+			SharingControllerImpl sharingController) {
+		return sharingController;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/threaded/NestedTreeList.java

@@ -1,54 +0,0 @@
-package org.briarproject.briar.android.threaded;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.api.client.MessageTree;
-import org.briarproject.briar.api.client.MessageTree.MessageNode;
-import org.briarproject.briar.client.MessageTreeImpl;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.List;
-
-import androidx.annotation.UiThread;
-
-@UiThread
-@NotNullByDefault
-public class NestedTreeList<T extends MessageNode> implements Iterable<T> {
-
-	private final MessageTree<T> tree = new MessageTreeImpl<>();
-	private List<T> depthFirstCollection = new ArrayList<>();
-
-	public void addAll(Collection<T> collection) {
-		tree.add(collection);
-		depthFirstCollection = new ArrayList<>(tree.depthFirstOrder());
-	}
-
-	public void add(T elem) {
-		tree.add(elem);
-		depthFirstCollection = new ArrayList<>(tree.depthFirstOrder());
-	}
-
-	public void clear() {
-		tree.clear();
-		depthFirstCollection.clear();
-	}
-
-	public T get(int index) {
-		return depthFirstCollection.get(index);
-	}
-
-	public int size() {
-		return depthFirstCollection.size();
-	}
-
-	public boolean contains(MessageId m) {
-		return tree.contains(m);
-	}
-
-	@Override
-	public Iterator<T> iterator() {
-		return depthFirstCollection.iterator();
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadItem.java

@@ -99,4 +99,14 @@ public abstract class ThreadItem implements MessageNode {
 		return highlighted;
 	}
 
+	@Override
+	public int hashCode() {
+		return messageId.hashCode();
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof ThreadItem &&
+				messageId.equals(((ThreadItem) o).messageId);
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadItemAdapter.java

@@ -4,39 +4,45 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.ItemReturningAdapter;
-import org.briarproject.briar.android.util.VersionedAdapter;
-
-import java.util.Collection;
 
 import javax.annotation.Nullable;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.UiThread;
+import androidx.recyclerview.widget.DiffUtil;
 import androidx.recyclerview.widget.LinearLayoutManager;
-import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.ListAdapter;
 
 import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
 
 @UiThread
+@NotNullByDefault
 public class ThreadItemAdapter<I extends ThreadItem>
-		extends RecyclerView.Adapter<BaseThreadItemViewHolder<I>>
-		implements VersionedAdapter, ItemReturningAdapter<I> {
+		extends ListAdapter<I, BaseThreadItemViewHolder<I>>
+		implements ItemReturningAdapter<I> {
 
 	static final int UNDEFINED = -1;
 
-	protected final NestedTreeList<I> items = new NestedTreeList<>();
 	private final ThreadItemListener<I> listener;
-	private final LinearLayoutManager layoutManager;
 
-	private volatile int revision = 0;
+	public ThreadItemAdapter(ThreadItemListener<I> listener) {
+		super(new DiffUtil.ItemCallback<I>() {
+			@Override
+			public boolean areItemsTheSame(I a, I b) {
+				return a.equals(b);
+			}
 
-	public ThreadItemAdapter(ThreadItemListener<I> listener,
-			LinearLayoutManager layoutManager) {
+			@Override
+			public boolean areContentsTheSame(I a, I b) {
+				return a.isHighlighted() == b.isHighlighted() &&
+						a.isRead() == b.isRead();
+			}
+		});
 		this.listener = listener;
-		this.layoutManager = layoutManager;
 	}
 
 	@NonNull
@@ -51,76 +57,27 @@ public class ThreadItemAdapter<I extends ThreadItem>
 	@Override
 	public void onBindViewHolder(@NonNull BaseThreadItemViewHolder<I> ui,
 			int position) {
-		I item = items.get(position);
+		I item = getItem(position);
 		ui.bind(item, listener);
 	}
 
-	@Override
-	public int getItemCount() {
-		return items.size();
-	}
-
-	@Override
-	public int getRevision() {
-		return revision;
-	}
-
-	@Override
-	public void incrementRevision() {
-		revision++;
-	}
-
-	void setItemWithIdVisible(MessageId messageId) {
-		int pos = 0;
-		for (I item : items) {
-			if (item.getId().equals(messageId)) {
-				layoutManager.scrollToPosition(pos);
-				break;
-			}
-			pos++;
-		}
-	}
-
-	public void setItems(Collection<I> items) {
-		this.items.clear();
-		this.items.addAll(items);
-		notifyDataSetChanged();
-	}
-
-	public void add(I item) {
-		items.add(item);
-		notifyItemInserted(findItemPosition(item));
-	}
-
-	@Nullable
-	public I getItemAt(int position) {
-		if (position == NO_POSITION || position >= items.size()) {
-			return null;
-		}
-		return items.get(position);
-	}
-
-	protected int findItemPosition(@Nullable I item) {
-		for (int i = 0; i < items.size(); i++) {
-			if (items.get(i).equals(item)) return i;
+	int findItemPosition(MessageId id) {
+		for (int i = 0; i < getItemCount(); i++) {
+			if (id.equals(getItem(i).getId())) return i;
 		}
 		return NO_POSITION; // Not found
 	}
 
-	boolean contains(MessageId m) {
-		return items.contains(m);
-	}
-
 	/**
 	 * Highlights the item with the given {@link MessageId}
 	 * and disables the highlight for a previously highlighted item, if any.
-	 *
+	 * <p>
 	 * Only one item can be highlighted at a time.
 	 */
 	void setHighlightedItem(@Nullable MessageId id) {
-		for (int i = 0; i < items.size(); i++) {
-			I item = items.get(i);
-			if (id != null && item.getId().equals(id)) {
+		for (int i = 0; i < getItemCount(); i++) {
+			I item = getItem(i);
+			if (item.getId().equals(id)) {
 				item.setHighlighted(true);
 				notifyItemChanged(i, item);
 			} else if (item.isHighlighted()) {
@@ -132,20 +89,27 @@ public class ThreadItemAdapter<I extends ThreadItem>
 
 	@Nullable
 	I getHighlightedItem() {
-		for (I i : items) {
-			if (i.isHighlighted()) return i;
+		for (I item : getCurrentList()) {
+			if (item.isHighlighted()) return item;
 		}
 		return null;
 	}
 
+	@Nullable
+	MessageId getFirstVisibleMessageId(LinearLayoutManager layoutManager) {
+		int position = layoutManager.findFirstVisibleItemPosition();
+		if (position == NO_POSITION) return null;
+		return getItemAt(position).getId();
+	}
+
 	/**
 	 * Returns the position of the first unread item below the current viewport
 	 */
-	int getVisibleUnreadPosBottom() {
+	int getVisibleUnreadPosBottom(LinearLayoutManager layoutManager) {
 		int positionBottom = layoutManager.findLastVisibleItemPosition();
 		if (positionBottom == NO_POSITION) return NO_POSITION;
-		for (int i = positionBottom + 1; i < items.size(); i++) {
-			if (!items.get(i).isRead()) return i;
+		for (int i = positionBottom + 1; i < getItemCount(); i++) {
+			if (!getItem(i).isRead()) return i;
 		}
 		return NO_POSITION;
 	}
@@ -153,11 +117,11 @@ public class ThreadItemAdapter<I extends ThreadItem>
 	/**
 	 * Returns the position of the first unread item above the current viewport
 	 */
-	int getVisibleUnreadPosTop() {
+	int getVisibleUnreadPosTop(LinearLayoutManager layoutManager) {
 		int positionTop = layoutManager.findFirstVisibleItemPosition();
 		int position = NO_POSITION;
-		for (int i = 0; i < items.size(); i++) {
-			if (i < positionTop && !items.get(i).isRead()) {
+		for (int i = 0; i < getItemCount(); i++) {
+			if (i < positionTop && !getItem(i).isRead()) {
 				position = i;
 			} else if (i >= positionTop) {
 				return position;
@@ -166,6 +130,11 @@ public class ThreadItemAdapter<I extends ThreadItem>
 		return NO_POSITION;
 	}
 
+	@Override
+	public I getItemAt(int position) {
+		return getItem(position);
+	}
+
 	public interface ThreadItemListener<I> {
 		void onReplyClick(I item);
 	}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadItemList.java

@@ -1,15 +0,0 @@
-package org.briarproject.briar.android.threaded;
-
-import org.briarproject.bramble.api.sync.MessageId;
-
-import java.util.List;
-
-import javax.annotation.Nullable;
-
-public interface ThreadItemList<I extends ThreadItem> extends List<I> {
-
-	@Nullable
-	MessageId getFirstVisibleItemId();
-
-	void setFirstVisibleId(@Nullable MessageId bottomVisibleItemId);
-}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadItemListImpl.java

@@ -1,23 +0,0 @@
-package org.briarproject.briar.android.threaded;
-
-import org.briarproject.bramble.api.sync.MessageId;
-
-import java.util.ArrayList;
-
-import javax.annotation.Nullable;
-
-public class ThreadItemListImpl<I extends ThreadItem> extends ArrayList<I>
-		implements ThreadItemList<I> {
-
-	private MessageId bottomVisibleItemId;
-
-	@Override
-	public MessageId getFirstVisibleItemId() {
-		return bottomVisibleItemId;
-	}
-
-	@Override
-	public void setFirstVisibleId(@Nullable MessageId bottomVisibleItemId) {
-		this.bottomVisibleItemId = bottomVisibleItemId;
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListActivity.java

@@ -2,25 +2,18 @@ package org.briarproject.briar.android.threaded;
 
 import android.content.Intent;
 import android.os.Bundle;
-import android.os.Parcelable;
 import android.view.MenuItem;
 
 import com.google.android.material.snackbar.Snackbar;
 
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.controller.SharingController;
-import org.briarproject.briar.android.controller.SharingController.SharingListener;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
+import org.briarproject.briar.android.sharing.SharingController.SharingInfo;
 import org.briarproject.briar.android.threaded.ThreadItemAdapter.ThreadItemListener;
-import org.briarproject.briar.android.threaded.ThreadListController.ThreadListDataSource;
-import org.briarproject.briar.android.threaded.ThreadListController.ThreadListListener;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 import org.briarproject.briar.android.view.TextInputView;
@@ -28,18 +21,13 @@ import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
 import org.briarproject.briar.android.view.UnreadMessageButton;
 import org.briarproject.briar.api.attachment.AttachmentHeader;
-import org.briarproject.briar.api.client.NamedGroup;
 
-import java.util.Collection;
 import java.util.List;
-import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.inject.Inject;
 
 import androidx.annotation.CallSuper;
 import androidx.annotation.StringRes;
-import androidx.annotation.UiThread;
 import androidx.appcompat.app.ActionBar;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
@@ -48,32 +36,19 @@ import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadItem, A extends ThreadItemAdapter<I>>
-		extends BriarActivity
-		implements ThreadListListener<I>, SendListener, SharingListener,
-		ThreadItemListener<I>, ThreadListDataSource {
+public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadItemAdapter<I>>
+		extends BriarActivity implements SendListener, ThreadItemListener<I> {
 
-	protected static final String KEY_REPLY_ID = "replyId";
-
-	private static final Logger LOG =
-			Logger.getLogger(ThreadListActivity.class.getName());
-
-	protected A adapter;
-	private ThreadScrollListener<I> scrollListener;
+	protected final A adapter = createAdapter();
+	protected abstract ThreadListViewModel<I> getViewModel();
+	protected abstract A createAdapter();
 	protected BriarRecyclerView list;
-	private LinearLayoutManager layoutManager;
 	protected TextInputView textInput;
 	protected TextSendController sendController;
 	protected GroupId groupId;
-	@Nullable
-	private Parcelable layoutManagerState;
-	@Nullable
-	private MessageId replyId;
 
-	protected abstract ThreadListController<G, I> getController();
-
-	@Inject
-	protected SharingController sharingController;
+	private LinearLayoutManager layoutManager;
+	private ThreadScrollListener<I> scrollListener;
 
 	@CallSuper
 	@Override
@@ -86,7 +61,8 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 		byte[] b = i.getByteArrayExtra(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No GroupId in intent.");
 		groupId = new GroupId(b);
-		getController().setGroupId(groupId);
+		ThreadListViewModel<I> viewModel = getViewModel();
+		viewModel.setGroupId(groupId);
 
 		textInput = findViewById(R.id.text_input_container);
 		sendController = new TextSendController(textInput, this, false);
@@ -100,131 +76,41 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 		list = findViewById(R.id.list);
 		layoutManager = new LinearLayoutManager(this);
 		list.setLayoutManager(layoutManager);
-		adapter = createAdapter(layoutManager);
 		list.setAdapter(adapter);
-		scrollListener = new ThreadScrollListener<>(adapter, getController(),
+		scrollListener = new ThreadScrollListener<>(adapter, viewModel,
 				upButton, downButton);
 		list.getRecyclerView().addOnScrollListener(scrollListener);
 
 		upButton.setOnClickListener(v -> {
-			int position = adapter.getVisibleUnreadPosTop();
+			int position = adapter.getVisibleUnreadPosTop(layoutManager);
 			if (position != NO_POSITION) {
 				list.getRecyclerView().scrollToPosition(position);
 			}
 		});
 		downButton.setOnClickListener(v -> {
-			int position = adapter.getVisibleUnreadPosBottom();
+			int position = adapter.getVisibleUnreadPosBottom(layoutManager);
 			if (position != NO_POSITION) {
 				list.getRecyclerView().scrollToPosition(position);
 			}
 		});
 
-		if (state != null) {
-			byte[] replyIdBytes = state.getByteArray(KEY_REPLY_ID);
-			if (replyIdBytes != null) replyId = new MessageId(replyIdBytes);
-		}
+		viewModel.getItems().observe(this, result -> result
+				.onError(this::handleException)
+				.onSuccess(this::displayItems)
+		);
 
-		sharingController.setSharingListener(this);
-		loadSharingContacts();
-	}
+		viewModel.getSharingInfo().observe(this, this::setToolbarSubTitle);
 
-	@Override
-	@Nullable
-	public MessageId getFirstVisibleMessageId() {
-		if (layoutManager != null && adapter != null) {
-			int position =
-					layoutManager.findFirstVisibleItemPosition();
-			I i = adapter.getItemAt(position);
-			return i == null ? null : i.getId();
-		}
-		return null;
-	}
-
-	protected abstract A createAdapter(LinearLayoutManager layoutManager);
-
-	protected void loadNamedGroup() {
-		getController().loadNamedGroup(
-				new UiResultExceptionHandler<G, DbException>(this) {
-					@Override
-					public void onResultUi(G groupItem) {
-						onNamedGroupLoaded(groupItem);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	@UiThread
-	protected abstract void onNamedGroupLoaded(G groupItem);
-
-	protected void loadItems() {
-		int revision = adapter.getRevision();
-		getController().loadItems(
-				new UiResultExceptionHandler<ThreadItemList<I>, DbException>(
-						this) {
-					@Override
-					public void onResultUi(ThreadItemList<I> items) {
-						if (revision == adapter.getRevision()) {
-							adapter.incrementRevision();
-							if (items.isEmpty()) {
-								list.showData();
-							} else {
-								displayItems(items);
-								updateTextInput();
-							}
-						} else {
-							LOG.info("Concurrent update, reloading");
-							loadItems();
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	private void displayItems(ThreadItemList<I> items) {
-		adapter.setItems(items);
-		MessageId messageId = items.getFirstVisibleItemId();
-		if (messageId != null)
-			adapter.setItemWithIdVisible(messageId);
-		list.showData();
-		if (layoutManagerState == null) {
-			list.scrollToPosition(0);  // Scroll to the top
-		} else {
-			layoutManager.onRestoreInstanceState(layoutManagerState);
-		}
-	}
-
-	protected void loadSharingContacts() {
-		getController().loadSharingContacts(
-				new UiResultExceptionHandler<Collection<ContactId>, DbException>(
-						this) {
-					@Override
-					public void onResultUi(Collection<ContactId> contacts) {
-						sharingController.addAll(contacts);
-						int online = sharingController.getOnlineCount();
-						setToolbarSubTitle(contacts.size(), online);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.getGroupRemoved().observe(this, removed -> {
+			if (removed) supportFinishAfterTransition();
+		});
 	}
 
 	@CallSuper
 	@Override
 	public void onStart() {
 		super.onStart();
-		sharingController.onStart();
-		loadItems();
+		getViewModel().blockAndClearNotifications();
 		list.startPeriodicUpdate();
 	}
 
@@ -232,91 +118,98 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 	@Override
 	public void onStop() {
 		super.onStop();
-		sharingController.onStop();
+		getViewModel().unblockNotifications();
 		list.stopPeriodicUpdate();
 	}
 
-	@Override
-	protected void onSaveInstanceState(Bundle outState) {
-		super.onSaveInstanceState(outState);
-		if (layoutManager != null) {
-			layoutManagerState = layoutManager.onSaveInstanceState();
-			outState.putParcelable("layoutManager", layoutManagerState);
-		}
-		if (replyId != null) {
-			outState.putByteArray(KEY_REPLY_ID, replyId.getBytes());
-		}
-	}
-
-	@Override
-	protected void onRestoreInstanceState(Bundle savedInstanceState) {
-		super.onRestoreInstanceState(savedInstanceState);
-		layoutManagerState = savedInstanceState.getParcelable("layoutManager");
-	}
-
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case android.R.id.home:
-				supportFinishAfterTransition();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		if (item.getItemId() == android.R.id.home) {
+			supportFinishAfterTransition();
+			return true;
 		}
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
 	public void onBackPressed() {
 		if (adapter.getHighlightedItem() != null) {
 			textInput.clearText();
-			replyId = null;
+			getViewModel().setReplyId(null);
 			updateTextInput();
 		} else {
 			super.onBackPressed();
 		}
 	}
 
+	@Override
+	protected void onDestroy() {
+		super.onDestroy();
+		// store list position, so we can restore it when coming back here
+		if (layoutManager != null && adapter != null) {
+			MessageId id = adapter.getFirstVisibleMessageId(layoutManager);
+			getViewModel().storeMessageId(id);
+		}
+	}
+
+	protected void displayItems(List<I> items) {
+		if (items.isEmpty()) {
+			list.showData();
+		} else {
+			adapter.submitList(items, () -> {
+				// do stuff *after* list had been updated
+				scrollAfterListCommitted();
+				updateTextInput();
+			});
+		}
+	}
+
+	/**
+	 * Scrolls to the first visible item last time the activity was open,
+	 * if one exists and this is the first time, the list gets displayed.
+	 * Or scrolls to a locally added item that has just been added to the list.
+	 */
+	private void scrollAfterListCommitted() {
+		MessageId restoredFirstVisibleItemId =
+				getViewModel().getAndResetRestoredMessageId();
+		MessageId scrollToItem =
+				getViewModel().getAndResetScrollToItem();
+		if (restoredFirstVisibleItemId != null) {
+			scrollToItemAtTop(restoredFirstVisibleItemId);
+		} else if (scrollToItem != null) {
+			scrollToItemAtTop(scrollToItem);
+		}
+		scrollListener.updateUnreadButtons(layoutManager);
+	}
+
 	@Override
 	public void onReplyClick(I item) {
-		replyId = item.getId();
+		getViewModel().setReplyId(item.getId());
 		updateTextInput();
 		// FIXME This does not work for a hardware keyboard
 		if (textInput.isKeyboardOpen()) {
-			scrollToItemAtTop(item);
+			scrollToItemAtTop(item.getId());
 		} else {
 			// wait with scrolling until keyboard opened
 			textInput.setOnKeyboardShownListener(() -> {
-				scrollToItemAtTop(item);
+				scrollToItemAtTop(item.getId());
 				textInput.setOnKeyboardShownListener(null);
 			});
 		}
 	}
 
-	@Override
-	public void onSharingInfoUpdated(int total, int online) {
-		setToolbarSubTitle(total, online);
-	}
-
-	@Override
-	public void onInvitationAccepted(ContactId c) {
-		sharingController.add(c);
-		setToolbarSubTitle(sharingController.getTotalCount(),
-				sharingController.getOnlineCount());
-	}
-
-	protected void setToolbarSubTitle(int total, int online) {
+	protected void setToolbarSubTitle(SharingInfo sharingInfo) {
 		ActionBar actionBar = getSupportActionBar();
 		if (actionBar != null) {
-			actionBar.setSubtitle(
-					getString(R.string.shared_with, total, online));
+			actionBar.setSubtitle(getString(R.string.shared_with,
+					sharingInfo.total, sharingInfo.online));
 		}
 	}
 
-	private void scrollToItemAtTop(I item) {
-		int position = adapter.findItemPosition(item);
+	private void scrollToItemAtTop(MessageId messageId) {
+		int position = adapter.findItemPosition(messageId);
 		if (position != NO_POSITION) {
-			layoutManager
-					.scrollToPositionWithOffset(position, 0);
+			layoutManager.scrollToPositionWithOffset(position, 0);
 		}
 	}
 
@@ -327,6 +220,7 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 	}
 
 	private void updateTextInput() {
+		MessageId replyId = getViewModel().getReplyId();
 		if (replyId != null) {
 			textInput.setHint(R.string.forum_message_reply_hint);
 			textInput.showSoftKeyboard();
@@ -341,54 +235,14 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 			List<AttachmentHeader> headers) {
 		if (isNullOrEmpty(text)) throw new AssertionError();
 
-		I replyItem = adapter.getHighlightedItem();
-		UiResultExceptionHandler<I, DbException> handler =
-				new UiResultExceptionHandler<I, DbException>(this) {
-					@Override
-					public void onResultUi(I result) {
-						addItem(result, true);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				};
-		getController().createAndStoreMessage(text, replyItem, handler);
+		MessageId replyId = getViewModel().getReplyId();
+		getViewModel().createAndStoreMessage(text, replyId);
 		textInput.hideSoftKeyboard();
 		textInput.clearText();
-		replyId = null;
+		getViewModel().setReplyId(null);
 		updateTextInput();
 	}
 
 	protected abstract int getMaxTextLength();
 
-	@Override
-	public void onItemReceived(I item) {
-		addItem(item, false);
-	}
-
-	@Override
-	public void onGroupRemoved() {
-		supportFinishAfterTransition();
-	}
-
-	private void addItem(I item, boolean isLocal) {
-		adapter.incrementRevision();
-		MessageId parent = item.getParentId();
-		if (parent != null && !adapter.contains(parent)) {
-			// We've incremented the adapter's revision, so the item will be
-			// loaded when its parent has been loaded
-			LOG.info("Ignoring item with missing parent");
-			return;
-		}
-		adapter.add(item);
-
-		if (isLocal) {
-			scrollToItemAtTop(item);
-		} else {
-			scrollListener.updateUnreadButtons(layoutManager);
-		}
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListController.java

@@ -1,60 +0,0 @@
-package org.briarproject.briar.android.threaded;
-
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.controller.ActivityLifecycleController;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.client.NamedGroup;
-
-import java.util.Collection;
-
-import javax.annotation.Nullable;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-public interface ThreadListController<G extends NamedGroup, I extends ThreadItem>
-		extends ActivityLifecycleController {
-
-	void setGroupId(GroupId groupId);
-
-	void loadNamedGroup(ResultExceptionHandler<G, DbException> handler);
-
-	void loadSharingContacts(
-			ResultExceptionHandler<Collection<ContactId>, DbException> handler);
-
-	void loadItems(
-			ResultExceptionHandler<ThreadItemList<I>, DbException> handler);
-
-	void markItemRead(I item);
-
-	void markItemsRead(Collection<I> items);
-
-	void createAndStoreMessage(String text, @Nullable I parentItem,
-			ResultExceptionHandler<I, DbException> handler);
-
-	void deleteNamedGroup(ExceptionHandler<DbException> handler);
-
-	interface ThreadListListener<I> extends ThreadListDataSource {
-
-		@UiThread
-		void onItemReceived(I item);
-
-		@UiThread
-		void onGroupRemoved();
-
-		@UiThread
-		void onInvitationAccepted(ContactId c);
-	}
-
-	interface ThreadListDataSource {
-
-		@UiThread @Nullable
-		MessageId getFirstVisibleMessageId();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListControllerImpl.java

@@ -1,273 +0,0 @@
-package org.briarproject.briar.android.threaded;
-
-import android.app.Activity;
-
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.identity.IdentityManager;
-import org.briarproject.bramble.api.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.briar.android.controller.DbControllerImpl;
-import org.briarproject.briar.android.controller.handler.ExceptionHandler;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.android.threaded.ThreadListController.ThreadListListener;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker;
-import org.briarproject.briar.api.client.NamedGroup;
-import org.briarproject.briar.api.client.PostHeader;
-import org.briarproject.briar.api.client.ThreadedMessage;
-
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import androidx.annotation.CallSuper;
-
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public abstract class ThreadListControllerImpl<G extends NamedGroup, I extends ThreadItem, H extends PostHeader, M extends ThreadedMessage, L extends ThreadListListener<I>>
-		extends DbControllerImpl
-		implements ThreadListController<G, I>, EventListener {
-
-	private static final Logger LOG =
-			Logger.getLogger(ThreadListControllerImpl.class.getName());
-
-	private final EventBus eventBus;
-	private final MessageTracker messageTracker;
-	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
-
-	private volatile GroupId groupId;
-
-	protected final IdentityManager identityManager;
-	protected final AndroidNotificationManager notificationManager;
-	protected final Executor cryptoExecutor;
-	protected final Clock clock;
-
-	// UI thread
-	protected L listener;
-
-	protected ThreadListControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, IdentityManager identityManager,
-			@CryptoExecutor Executor cryptoExecutor, EventBus eventBus,
-			Clock clock, AndroidNotificationManager notificationManager,
-			MessageTracker messageTracker) {
-		super(dbExecutor, lifecycleManager);
-		this.identityManager = identityManager;
-		this.cryptoExecutor = cryptoExecutor;
-		this.notificationManager = notificationManager;
-		this.clock = clock;
-		this.eventBus = eventBus;
-		this.messageTracker = messageTracker;
-	}
-
-	@Override
-	public void setGroupId(GroupId groupId) {
-		this.groupId = groupId;
-	}
-
-	@CallSuper
-	@SuppressWarnings("unchecked")
-	@Override
-	public void onActivityCreate(Activity activity) {
-		listener = (L) activity;
-	}
-
-	@CallSuper
-	@Override
-	public void onActivityStart() {
-		notificationManager.blockNotification(getGroupId());
-		eventBus.addListener(this);
-	}
-
-	@CallSuper
-	@Override
-	public void onActivityStop() {
-		notificationManager.unblockNotification(getGroupId());
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	public void onActivityDestroy() {
-		MessageId messageId = listener.getFirstVisibleMessageId();
-		if (messageId != null) {
-			dbExecutor.execute(() -> {
-				try {
-					messageTracker.storeMessageId(groupId, messageId);
-				} catch (DbException e) {
-					logException(LOG, WARNING, e);
-				}
-			});
-		}
-	}
-
-	@CallSuper
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent s = (GroupRemovedEvent) e;
-			if (s.getGroup().getId().equals(getGroupId())) {
-				LOG.info("Group removed");
-				listener.onGroupRemoved();
-			}
-		}
-	}
-
-	@Override
-	public void loadNamedGroup(
-			ResultExceptionHandler<G, DbException> handler) {
-		checkGroupId();
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				G groupItem = loadNamedGroup();
-				logDuration(LOG, "Loading group", start);
-				handler.onResult(groupItem);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@DatabaseExecutor
-	protected abstract G loadNamedGroup() throws DbException;
-
-	@Override
-	public void loadItems(
-			ResultExceptionHandler<ThreadItemList<I>, DbException> handler) {
-		checkGroupId();
-		runOnDbThread(() -> {
-			try {
-				// Load headers
-				long start = now();
-				Collection<H> headers = loadHeaders();
-				logDuration(LOG, "Loading headers", start);
-
-				// Load bodies into cache
-				start = now();
-				for (H header : headers) {
-					if (!textCache.containsKey(header.getId())) {
-						textCache.put(header.getId(),
-								loadMessageText(header));
-					}
-				}
-				logDuration(LOG, "Loading bodies", start);
-
-				// Build and hand over items
-				handler.onResult(buildItems(headers));
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@DatabaseExecutor
-	protected abstract Collection<H> loadHeaders() throws DbException;
-
-	@DatabaseExecutor
-	protected abstract String loadMessageText(H header) throws DbException;
-
-	@Override
-	public void markItemRead(I item) {
-		markItemsRead(Collections.singletonList(item));
-	}
-
-	@Override
-	public void markItemsRead(Collection<I> items) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				for (I i : items) {
-					markRead(i.getId());
-				}
-				logDuration(LOG, "Marking read", start);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	@DatabaseExecutor
-	protected abstract void markRead(MessageId id) throws DbException;
-
-	protected void storePost(M msg, String text,
-			ResultExceptionHandler<I, DbException> resultHandler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				H header = addLocalMessage(msg);
-				textCache.put(msg.getMessage().getId(), text);
-				logDuration(LOG, "Storing message", start);
-				resultHandler.onResult(buildItem(header, text));
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				resultHandler.onException(e);
-			}
-		});
-	}
-
-	@DatabaseExecutor
-	protected abstract H addLocalMessage(M message) throws DbException;
-
-	@Override
-	public void deleteNamedGroup(ExceptionHandler<DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				G groupItem = loadNamedGroup();
-				deleteNamedGroup(groupItem);
-				logDuration(LOG, "Removing group", start);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@DatabaseExecutor
-	protected abstract void deleteNamedGroup(G groupItem) throws DbException;
-
-	private ThreadItemList<I> buildItems(Collection<H> headers)
-			throws DbException {
-		ThreadItemList<I> items = new ThreadItemListImpl<>();
-		for (H h : headers) {
-			items.add(buildItem(h, textCache.get(h.getId())));
-		}
-		MessageId msgId = messageTracker.loadStoredMessageId(groupId);
-		if (LOG.isLoggable(INFO))
-			LOG.info("Loaded last top visible message id " + msgId);
-		items.setFirstVisibleId(msgId);
-		return items;
-	}
-
-	protected abstract I buildItem(H header, String text);
-
-	protected GroupId getGroupId() {
-		checkGroupId();
-		return groupId;
-	}
-
-	private void checkGroupId() {
-		if (groupId == null) throw new IllegalStateException();
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListViewModel.java

@@ -0,0 +1,256 @@
+package org.briarproject.briar.android.threaded;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.crypto.CryptoExecutor;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.identity.IdentityManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.briar.android.sharing.SharingController;
+import org.briarproject.briar.android.sharing.SharingController.SharingInfo;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker;
+import org.briarproject.briar.api.client.MessageTree;
+import org.briarproject.briar.client.MessageTreeImpl;
+
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import androidx.annotation.CallSuper;
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public abstract class ThreadListViewModel<I extends ThreadItem>
+		extends DbViewModel implements EventListener {
+
+	private static final Logger LOG =
+			getLogger(ThreadListViewModel.class.getName());
+
+	protected final IdentityManager identityManager;
+	protected final AndroidNotificationManager notificationManager;
+	protected final SharingController sharingController;
+	protected final Executor cryptoExecutor;
+	protected final Clock clock;
+	private final MessageTracker messageTracker;
+	private final EventBus eventBus;
+
+	// UIThread
+	private final MessageTree<I> messageTree = new MessageTreeImpl<>();
+	private final MutableLiveData<LiveResult<List<I>>> items =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> groupRemoved =
+			new MutableLiveData<>();
+	private final AtomicReference<MessageId> scrollToItem =
+			new AtomicReference<>();
+
+	protected volatile GroupId groupId;
+	@Nullable
+	private MessageId replyId;
+	/**
+	 * Stored list position. Needs to be loaded and set before the list itself.
+	 */
+	private final AtomicReference<MessageId> storedMessageId =
+			new AtomicReference<>();
+
+	public ThreadListViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			IdentityManager identityManager,
+			AndroidNotificationManager notificationManager,
+			SharingController sharingController,
+			@CryptoExecutor Executor cryptoExecutor,
+			Clock clock,
+			MessageTracker messageTracker,
+			EventBus eventBus) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.identityManager = identityManager;
+		this.notificationManager = notificationManager;
+		this.cryptoExecutor = cryptoExecutor;
+		this.clock = clock;
+		this.sharingController = sharingController;
+		this.messageTracker = messageTracker;
+		this.eventBus = eventBus;
+		this.eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+		sharingController.onCleared();
+	}
+
+	/**
+	 * Needs to be called right after initialization,
+	 * before calling any other methods.
+	 */
+	public final void setGroupId(GroupId groupId) {
+		boolean needsInitialLoad = this.groupId == null;
+		this.groupId = groupId;
+		if (needsInitialLoad) performInitialLoad();
+	}
+
+	@CallSuper
+	protected void performInitialLoad() {
+		// load stored MessageId (last list position) before the list itself
+		loadStoredMessageId();
+		loadItems();
+		loadSharingContacts();
+	}
+
+	protected abstract void clearNotifications();
+
+	void blockAndClearNotifications() {
+		notificationManager.blockNotification(groupId);
+		clearNotifications();
+	}
+
+	void unblockNotifications() {
+		notificationManager.unblockNotification(groupId);
+	}
+
+	@Override
+	@CallSuper
+	public void eventOccurred(Event e) {
+		if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent s = (GroupRemovedEvent) e;
+			if (s.getGroup().getId().equals(groupId)) {
+				LOG.info("Group removed");
+				groupRemoved.setValue(true);
+			}
+		}
+	}
+
+	private void loadStoredMessageId() {
+		runOnDbThread(() -> {
+			try {
+				storedMessageId
+						.set(messageTracker.loadStoredMessageId(groupId));
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Loaded last top visible message id " +
+							storedMessageId);
+				}
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	public abstract void loadItems();
+
+	public abstract void createAndStoreMessage(String text,
+			@Nullable MessageId parentMessageId);
+
+	/**
+	 * Loads the ContactIds of all contacts the group is shared with
+	 * and adds them to {@link SharingController}.
+	 */
+	protected abstract void loadSharingContacts();
+
+	@UiThread
+	protected void setItems(LiveResult<List<I>> items) {
+		if (items.hasError()) {
+			this.items.setValue(items);
+		} else {
+			messageTree.clear();
+			// not null, because hasError() is false
+			messageTree.add(requireNonNull(items.getResultOrNull()));
+			LiveResult<List<I>> result =
+					new LiveResult<>(messageTree.depthFirstOrder());
+			this.items.setValue(result);
+		}
+	}
+
+	/**
+	 * Add a remote item on the UI thread.
+	 *
+	 * @param scrollToItem whether the list will scroll to the newly added item
+	 */
+	@UiThread
+	protected void addItem(I item, boolean scrollToItem) {
+		messageTree.add(item);
+		if (scrollToItem) this.scrollToItem.set(item.getId());
+		items.setValue(new LiveResult<>(messageTree.depthFirstOrder()));
+	}
+
+	@UiThread
+	void setReplyId(@Nullable MessageId id) {
+		replyId = id;
+	}
+
+	@UiThread
+	@Nullable
+	MessageId getReplyId() {
+		return replyId;
+	}
+
+	void storeMessageId(@Nullable MessageId messageId) {
+		if (messageId != null) {
+			runOnDbThread(() -> {
+				try {
+					messageTracker.storeMessageId(groupId, messageId);
+				} catch (DbException e) {
+					logException(LOG, WARNING, e);
+				}
+			});
+		}
+	}
+
+	protected abstract void markItemRead(I item);
+
+	/**
+	 * Returns the {@link MessageId} of the item that was at the top of the
+	 * list last time or null if there has been nothing stored, yet.
+	 */
+	@Nullable
+	MessageId getAndResetRestoredMessageId() {
+		return storedMessageId.getAndSet(null);
+	}
+
+	LiveData<LiveResult<List<I>>> getItems() {
+		return items;
+	}
+
+	LiveData<SharingInfo> getSharingInfo() {
+		return sharingController.getSharingInfo();
+	}
+
+	LiveData<Boolean> getGroupRemoved() {
+		return groupRemoved;
+	}
+
+	@Nullable
+	MessageId getAndResetScrollToItem() {
+		return scrollToItem.getAndSet(null);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadScrollListener.java

@@ -20,15 +20,15 @@ class ThreadScrollListener<I extends ThreadItem>
 	private static final Logger LOG =
 			getLogger(ThreadScrollListener.class.getName());
 
-	private final ThreadListController<?, I> controller;
+	private final ThreadListViewModel<I> viewModel;
 	private final UnreadMessageButton upButton, downButton;
 
 	ThreadScrollListener(ThreadItemAdapter<I> adapter,
-			ThreadListController<?, I> controller,
+			ThreadListViewModel<I> viewModel,
 			UnreadMessageButton upButton,
 			UnreadMessageButton downButton) {
 		super(adapter);
-		this.controller = controller;
+		this.viewModel = viewModel;
 		this.upButton = upButton;
 		this.downButton = downButton;
 	}
@@ -44,7 +44,7 @@ class ThreadScrollListener<I extends ThreadItem>
 	protected void onItemVisible(I item) {
 		if (!item.isRead()) {
 			item.setRead(true);
-			controller.markItemRead(item);
+			viewModel.markItemRead(item);
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/DbViewModel.java

@@ -5,6 +5,7 @@ import android.app.Application;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbCallable;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.DbRunnable;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
@@ -23,6 +24,7 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 import androidx.arch.core.util.Function;
+import androidx.core.util.Consumer;
 import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.recyclerview.widget.RecyclerView;
@@ -57,8 +59,8 @@ public abstract class DbViewModel extends AndroidViewModel {
 	}
 
 	/**
-	 * Runs the given task on the {@link DatabaseExecutor}
-	 * and waits for the DB to open.
+	 * Waits for the DB to open and runs the given task on the
+	 * {@link DatabaseExecutor}.
 	 * <p>
 	 * If you need a list of items to be displayed in a
 	 * {@link RecyclerView.Adapter},
@@ -76,6 +78,29 @@ public abstract class DbViewModel extends AndroidViewModel {
 		});
 	}
 
+	/**
+	 * Waits for the DB to open and runs the given task on the
+	 * {@link DatabaseExecutor}.
+	 * <p>
+	 * If you need a list of items to be displayed in a
+	 * {@link RecyclerView.Adapter},
+	 * use {@link #loadList(DbCallable, UiConsumer)} instead.
+	 */
+	protected void runOnDbThread(boolean readOnly,
+			DbRunnable<Exception> task, Consumer<Exception> err) {
+		dbExecutor.execute(() -> {
+			try {
+				lifecycleManager.waitForDatabase();
+				db.transaction(readOnly, task);
+			} catch (InterruptedException e) {
+				LOG.warning("Interrupted while waiting for database");
+				Thread.currentThread().interrupt();
+			} catch (Exception e) {
+				err.accept(e);
+			}
+		});
+	}
+
 	/**
 	 * Loads a list of items on the {@link DatabaseExecutor} within a single
 	 * {@link Transaction} and publishes it as a {@link LiveResult}

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/LiveEvent.java

@@ -39,6 +39,17 @@ public class LiveEvent<T> extends LiveData<LiveEvent.ConsumableEvent<T>> {
 		super.observeForever(observer);
 	}
 
+	/**
+	 * Returns the last value of the event (even if already consumed)
+	 * or null if there hasn't been any value so far.
+	 */
+	@Nullable
+	public T getLastValue() {
+		ConsumableEvent<T> event = getValue();
+		if (event == null) return null;
+		return event.content;
+	}
+
 	static class ConsumableEvent<T> {
 
 		private final T content;

briar-android/src/main/res/menu/group_actions.xml

@@ -1,36 +1,44 @@
 <?xml version="1.0" encoding="utf-8"?>
-<menu
-	xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:app="http://schemas.android.com/apk/res-auto">
+<menu 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">
 
 	<item
 		android:id="@+id/action_group_invite"
 		android:icon="@drawable/social_share_white"
 		android:title="@string/groups_invite_members"
-		app:showAsAction="ifRoom"/>
+		android:visible="false"
+		app:showAsAction="ifRoom"
+		tools:visible="true" />
 
 	<item
 		android:id="@+id/action_group_member_list"
 		android:icon="@drawable/ic_group_white"
 		android:title="@string/groups_member_list"
-		app:showAsAction="never"/>
+		app:showAsAction="never" />
 
 	<item
 		android:id="@+id/action_group_reveal"
 		android:icon="@drawable/ic_visibility_white"
 		android:title="@string/groups_reveal_contacts"
-		app:showAsAction="never"/>
+		android:visible="false"
+		app:showAsAction="never"
+		tools:visible="true" />
 
 	<item
 		android:id="@+id/action_group_leave"
 		android:icon="@drawable/action_delete_white"
 		android:title="@string/groups_leave"
-		app:showAsAction="never"/>
+		android:visible="false"
+		app:showAsAction="never"
+		tools:visible="true" />
 
 	<item
 		android:id="@+id/action_group_dissolve"
 		android:icon="@drawable/action_delete_white"
 		android:title="@string/groups_dissolve"
-		app:showAsAction="never"/>
+		android:visible="false"
+		app:showAsAction="never"
+		tools:visible="true" />
 
 </menu>

briar-android/src/test/java/org/briarproject/briar/android/forum/ForumActivityTest.java

@@ -1,120 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import android.content.Intent;
-
-import junit.framework.Assert;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.briar.api.identity.AuthorInfo;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
-import org.briarproject.briar.android.threaded.ThreadItemAdapter;
-import org.briarproject.briar.android.threaded.ThreadItemList;
-import org.briarproject.briar.android.threaded.ThreadItemListImpl;
-import org.junit.Before;
-import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.ArgumentCaptor;
-import org.mockito.Captor;
-import org.mockito.MockitoAnnotations;
-import org.robolectric.Robolectric;
-import org.robolectric.RobolectricTestRunner;
-import org.robolectric.annotation.Config;
-
-import java.util.Arrays;
-
-import static junit.framework.Assert.assertEquals;
-import static org.briarproject.briar.api.identity.AuthorInfo.Status.UNKNOWN;
-import static org.briarproject.bramble.test.TestUtils.getAuthor;
-import static org.briarproject.bramble.test.TestUtils.getRandomId;
-import static org.briarproject.bramble.util.StringUtils.getRandomString;
-import static org.briarproject.briar.api.forum.ForumConstants.MAX_FORUM_POST_TEXT_LENGTH;
-import static org.mockito.Mockito.times;
-import static org.mockito.Mockito.verify;
-
-@RunWith(RobolectricTestRunner.class)
-@Config(sdk = 21)
-public class ForumActivityTest {
-
-	private final static MessageId[] MESSAGE_IDS = new MessageId[6];
-
-	static {
-		for (int i = 0; i < MESSAGE_IDS.length; i++)
-			MESSAGE_IDS[i] = new MessageId(getRandomId());
-	}
-
-	private final static MessageId[] PARENT_IDS = {
-			null,
-			MESSAGE_IDS[0],
-			MESSAGE_IDS[1],
-			MESSAGE_IDS[2],
-			MESSAGE_IDS[0],
-			null
-	};
-
-	/*
-		1
-		-> 2
-		   -> 3
-			  -> 4
-		   5
-		6
-	 */
-	private final static int[] LEVELS = {
-			0, 1, 2, 3, 1, 0
-	};
-
-	private TestForumActivity forumActivity;
-	@Captor
-	private ArgumentCaptor<UiResultExceptionHandler<ThreadItemList<ForumPostItem>, DbException>>
-			rc;
-
-	@Before
-	public void setUp() {
-		MockitoAnnotations.initMocks(this);
-		Intent intent = new Intent();
-		intent.putExtra("briar.GROUP_ID", getRandomId());
-		forumActivity = Robolectric.buildActivity(TestForumActivity.class,
-				intent).create().start().resume().get();
-	}
-
-	private ThreadItemList<ForumPostItem> getDummyData() {
-		ForumPostItem[] forumPostItems = new ForumPostItem[6];
-		for (int i = 0; i < forumPostItems.length; i++) {
-			Author author = getAuthor();
-			String text = getRandomString(MAX_FORUM_POST_TEXT_LENGTH);
-			forumPostItems[i] = new ForumPostItem(MESSAGE_IDS[i], PARENT_IDS[i],
-					text, System.currentTimeMillis(), author,
-					new AuthorInfo(UNKNOWN));
-			forumPostItems[i].setLevel(LEVELS[i]);
-		}
-		ThreadItemList<ForumPostItem> list = new ThreadItemListImpl<>();
-		list.addAll(Arrays.asList(forumPostItems));
-		return list;
-	}
-
-	@Test
-	public void testNestedEntries() {
-		ForumController mc = forumActivity.getController();
-		ThreadItemList<ForumPostItem> dummyData = getDummyData();
-		verify(mc, times(1)).loadItems(rc.capture());
-		rc.getValue().onResult(dummyData);
-		ThreadItemAdapter<ForumPostItem> adapter = forumActivity.getAdapter();
-		Assert.assertNotNull(adapter);
-		assertEquals(6, adapter.getItemCount());
-		assertEquals(dummyData.get(0).getText(),
-				adapter.getItemAt(0).getText());
-		assertEquals(dummyData.get(1).getText(),
-				adapter.getItemAt(1).getText());
-		assertEquals(dummyData.get(2).getText(),
-				adapter.getItemAt(2).getText());
-		assertEquals(dummyData.get(3).getText(),
-				adapter.getItemAt(3).getText());
-		assertEquals(dummyData.get(4).getText(),
-				adapter.getItemAt(4).getText());
-		assertEquals(dummyData.get(5).getText(),
-				adapter.getItemAt(5).getText());
-	}
-
-}

briar-android/src/test/java/org/briarproject/briar/android/forum/TestForumActivity.java

@@ -1,65 +0,0 @@
-package org.briarproject.briar.android.forum;
-
-import android.os.Bundle;
-
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityModule;
-import org.briarproject.briar.android.activity.BaseActivity;
-import org.briarproject.briar.android.controller.BriarController;
-import org.briarproject.briar.android.controller.BriarControllerImpl;
-import org.briarproject.briar.android.threaded.ThreadItemAdapter;
-import org.mockito.Mockito;
-
-import javax.annotation.Nullable;
-
-/**
- * This class exposes the ForumController and offers the possibility to
- * override it.
- */
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class TestForumActivity extends ForumActivity {
-
-	@Override
-	public ForumController getController() {
-		return forumController;
-	}
-
-	public ThreadItemAdapter<ForumPostItem> getAdapter() {
-		return adapter;
-	}
-
-	@Override
-	public void onCreate(@Nullable Bundle state) {
-		setTheme(R.style.BriarTheme_NoActionBar);
-		super.onCreate(state);
-	}
-
-	@Override
-	protected ActivityModule getActivityModule() {
-		return new ActivityModule(this) {
-
-			@Override
-			protected BriarController provideBriarController(
-					BriarControllerImpl briarController) {
-				BriarController c = Mockito.mock(BriarController.class);
-				Mockito.when(c.accountSignedIn()).thenReturn(true);
-				return c;
-			}
-
-		};
-	}
-
-	@Override
-	protected ForumModule getForumModule() {
-		return new ForumModule() {
-			@Override
-			ForumController provideForumController(BaseActivity activity,
-					ForumControllerImpl forumController) {
-				return Mockito.mock(ForumController.class);
-			}
-		};
-	}
-}

briar-api/src/main/java/org/briarproject/briar/api/client/MessageTree.java

@@ -4,7 +4,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 
 import java.util.Collection;
-import java.util.Comparator;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -15,11 +15,9 @@ public interface MessageTree<T extends MessageTree.MessageNode> {
 
 	void add(T node);
 
-	void setComparator(Comparator<T> comparator);
-
 	void clear();
 
-	Collection<T> depthFirstOrder();
+	List<T> depthFirstOrder();
 
 	boolean contains(MessageId m);
 

briar-api/src/main/java/org/briarproject/briar/api/forum/ForumManager.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 
 import java.util.Collection;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -59,6 +60,12 @@ public interface ForumManager {
 	 */
 	ForumPostHeader addLocalPost(ForumPost p) throws DbException;
 
+	/**
+	 * Stores a local forum post.
+	 */
+	ForumPostHeader addLocalPost(Transaction txn, ForumPost p)
+			throws DbException;
+
 	/**
 	 * Returns the forum with the given ID.
 	 */
@@ -84,11 +91,22 @@ public interface ForumManager {
 	 */
 	String getPostText(MessageId m) throws DbException;
 
+	/**
+	 * Returns the text of the forum post with the given ID.
+	 */
+	String getPostText(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Returns the headers of all posts in the given forum.
 	 */
 	Collection<ForumPostHeader> getPostHeaders(GroupId g) throws DbException;
 
+	/**
+	 * Returns the headers of all posts in the given forum.
+	 */
+	List<ForumPostHeader> getPostHeaders(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Registers a hook to be called whenever a forum is removed.
 	 */
@@ -97,7 +115,6 @@ public interface ForumManager {
 	/**
 	 * Returns the group count for the given forum.
 	 */
-	@Deprecated
 	GroupCount getGroupCount(GroupId g) throws DbException;
 
 	/**

briar-api/src/main/java/org/briarproject/briar/api/privategroup/JoinMessageHeader.java

@@ -8,21 +8,14 @@ import javax.annotation.concurrent.Immutable;
 @NotNullByDefault
 public class JoinMessageHeader extends GroupMessageHeader {
 
-	private final Visibility visibility;
 	private final boolean isInitial;
 
-	public JoinMessageHeader(GroupMessageHeader h, Visibility visibility,
-			boolean isInitial) {
+	public JoinMessageHeader(GroupMessageHeader h, boolean isInitial) {
 		super(h.getGroupId(), h.getId(), h.getParentId(), h.getTimestamp(),
 				h.getAuthor(), h.getAuthorInfo(), h.isRead());
-		this.visibility = visibility;
 		this.isInitial = isInitial;
 	}
 
-	public Visibility getVisibility() {
-		return visibility;
-	}
-
 	public boolean isInitial() {
 		return isInitial;
 	}

briar-api/src/main/java/org/briarproject/briar/api/privategroup/PrivateGroupManager.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 
 import java.util.Collection;
+import java.util.List;
 
 @NotNullByDefault
 public interface PrivateGroupManager {
@@ -81,6 +82,12 @@ public interface PrivateGroupManager {
 	 */
 	GroupMessageHeader addLocalMessage(GroupMessage p) throws DbException;
 
+	/**
+	 * Stores and sends a local private group message.
+	 */
+	GroupMessageHeader addLocalMessage(Transaction txn, GroupMessage p)
+			throws DbException;
+
 	/**
 	 * Returns the private group with the given ID.
 	 */
@@ -107,16 +114,33 @@ public interface PrivateGroupManager {
 	 */
 	String getMessageText(MessageId m) throws DbException;
 
+	/**
+	 * Returns the text of the private group message with the given ID.
+	 */
+	String getMessageText(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Returns the headers of all messages in the given private group.
 	 */
 	Collection<GroupMessageHeader> getHeaders(GroupId g) throws DbException;
 
+	/**
+	 * Returns the headers of all messages in the given private group.
+	 */
+	List<GroupMessageHeader> getHeaders(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Returns all members of the given private group.
 	 */
 	Collection<GroupMember> getMembers(GroupId g) throws DbException;
 
+	/**
+	 * Returns all members of the given private group.
+	 */
+	Collection<GroupMember> getMembers(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Returns true if the given author is a member of the given private group.
 	 */

briar-api/src/main/java/org/briarproject/briar/api/sharing/SharingManager.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.api.sharing;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.briar.api.client.SessionId;
@@ -45,6 +46,12 @@ public interface SharingManager<S extends Shareable>
 	 */
 	Collection<Contact> getSharedWith(GroupId g) throws DbException;
 
+	/**
+	 * Returns all contacts with whom the given group is shared.
+	 */
+	Collection<Contact> getSharedWith(Transaction txn, GroupId g)
+			throws DbException;
+
 	/**
 	 * Returns true if the group not already shared and no invitation is open
 	 */

briar-core/src/main/java/org/briarproject/briar/client/MessageTreeImpl.java

@@ -30,7 +30,7 @@ public class MessageTreeImpl<T extends MessageTree.MessageNode>
 	private final List<List<T>> unsortedLists = new ArrayList<>();
 
 	@SuppressWarnings("UseCompareMethod")
-	private Comparator<T> comparator = (o1, o2) ->
+	private final Comparator<T> comparator = (o1, o2) ->
 			Long.valueOf(o1.getTimestamp()).compareTo(o2.getTimestamp());
 
 	@Override
@@ -79,6 +79,7 @@ public class MessageTreeImpl<T extends MessageTree.MessageNode>
 	@GuardedBy("this")
 	private void sortUnsorted() {
 		for (List<T> list : unsortedLists) {
+			//noinspection Java8ListSort
 			Collections.sort(list, comparator);
 		}
 		unsortedLists.clear();
@@ -95,17 +96,7 @@ public class MessageTreeImpl<T extends MessageTree.MessageNode>
 	}
 
 	@Override
-	public synchronized void setComparator(Comparator<T> comparator) {
-		this.comparator = comparator;
-		// Sort all lists with the new comparator
-		Collections.sort(roots, comparator);
-		for (Map.Entry<MessageId, List<T>> entry : nodeMap.entrySet()) {
-			Collections.sort(entry.getValue(), comparator);
-		}
-	}
-
-	@Override
-	public synchronized Collection<T> depthFirstOrder() {
+	public synchronized List<T> depthFirstOrder() {
 		List<T> orderedList = new ArrayList<>();
 		for (T root : roots) {
 			traverse(orderedList, root, 0);

briar-core/src/main/java/org/briarproject/briar/forum/ForumManagerImpl.java

@@ -126,29 +126,30 @@ class ForumManagerImpl extends BdfIncomingMessageHook implements ForumManager {
 
 	@Override
 	public ForumPostHeader addLocalPost(ForumPost p) throws DbException {
-		return db.transactionWithResult(false, txn -> {
-			try {
-				return addLocalPost(txn, p);
-			} catch (FormatException e) {
-				throw new AssertionError(e);
-			}
-		});
+		return db.transactionWithResult(false, txn -> addLocalPost(txn, p));
 	}
 
-	private ForumPostHeader addLocalPost(Transaction txn, ForumPost p)
-			throws DbException, FormatException {
-		BdfDictionary meta = new BdfDictionary();
-		meta.put(KEY_TIMESTAMP, p.getMessage().getTimestamp());
-		if (p.getParent() != null) meta.put(KEY_PARENT, p.getParent());
-		Author a = p.getAuthor();
-		meta.put(KEY_AUTHOR, clientHelper.toList(a));
-		meta.put(KEY_LOCAL, true);
-		meta.put(MSG_KEY_READ, true);
-		clientHelper.addLocalMessage(txn, p.getMessage(), meta, true, false);
-		messageTracker.trackOutgoingMessage(txn, p.getMessage());
-		AuthorInfo authorInfo = authorManager.getMyAuthorInfo(txn);
-		return new ForumPostHeader(p.getMessage().getId(), p.getParent(),
-				p.getMessage().getTimestamp(), p.getAuthor(), authorInfo, true);
+	@Override
+	public ForumPostHeader addLocalPost(Transaction txn, ForumPost p)
+			throws DbException {
+		try {
+			BdfDictionary meta = new BdfDictionary();
+			meta.put(KEY_TIMESTAMP, p.getMessage().getTimestamp());
+			if (p.getParent() != null) meta.put(KEY_PARENT, p.getParent());
+			Author a = p.getAuthor();
+			meta.put(KEY_AUTHOR, clientHelper.toList(a));
+			meta.put(KEY_LOCAL, true);
+			meta.put(MSG_KEY_READ, true);
+			clientHelper
+					.addLocalMessage(txn, p.getMessage(), meta, true, false);
+			messageTracker.trackOutgoingMessage(txn, p.getMessage());
+			AuthorInfo authorInfo = authorManager.getMyAuthorInfo(txn);
+			return new ForumPostHeader(p.getMessage().getId(), p.getParent(),
+					p.getMessage().getTimestamp(), p.getAuthor(), authorInfo,
+					true);
+		} catch (FormatException e) {
+			throw new AssertionError(e);
+		}
 	}
 
 	@Override
@@ -192,6 +193,15 @@ class ForumManagerImpl extends BdfIncomingMessageHook implements ForumManager {
 		}
 	}
 
+	@Override
+	public String getPostText(Transaction txn, MessageId m) throws DbException {
+		try {
+			return getPostText(clientHelper.getMessageAsList(txn, m));
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	private String getPostText(BdfList body) throws FormatException {
 		// Parent ID, author, text, signature
 		return body.getString(2);
@@ -200,33 +210,35 @@ class ForumManagerImpl extends BdfIncomingMessageHook implements ForumManager {
 	@Override
 	public Collection<ForumPostHeader> getPostHeaders(GroupId g)
 			throws DbException {
+		return db.transactionWithResult(true, txn -> getPostHeaders(txn, g));
+	}
+
+	@Override
+	public List<ForumPostHeader> getPostHeaders(Transaction txn, GroupId g)
+			throws DbException {
 		try {
-			return db.transactionWithResult(true, txn -> {
-				Collection<ForumPostHeader> headers = new ArrayList<>();
-				Map<MessageId, BdfDictionary> metadata =
-						clientHelper.getMessageMetadataAsDictionary(txn, g);
-				// get all authors we need to get the info for
-				Set<AuthorId> authors = new HashSet<>();
-				for (Entry<MessageId, BdfDictionary> entry :
-						metadata.entrySet()) {
-					BdfList authorList = entry.getValue().getList(KEY_AUTHOR);
-					Author a = clientHelper.parseAndValidateAuthor(authorList);
-					authors.add(a.getId());
-				}
-				// get information for all authors
-				Map<AuthorId, AuthorInfo> authorInfos = new HashMap<>();
-				for (AuthorId id : authors) {
-					authorInfos.put(id, authorManager.getAuthorInfo(txn, id));
-				}
-				// Parse the metadata
-				for (Entry<MessageId, BdfDictionary> entry :
-						metadata.entrySet()) {
-					BdfDictionary meta = entry.getValue();
-					headers.add(getForumPostHeader(txn, entry.getKey(), meta,
-							authorInfos));
-				}
-				return headers;
-			});
+			List<ForumPostHeader> headers = new ArrayList<>();
+			Map<MessageId, BdfDictionary> metadata =
+					clientHelper.getMessageMetadataAsDictionary(txn, g);
+			// get all authors we need to get the info for
+			Set<AuthorId> authors = new HashSet<>();
+			for (Entry<MessageId, BdfDictionary> entry : metadata.entrySet()) {
+				BdfList authorList = entry.getValue().getList(KEY_AUTHOR);
+				Author a = clientHelper.parseAndValidateAuthor(authorList);
+				authors.add(a.getId());
+			}
+			// get information for all authors
+			Map<AuthorId, AuthorInfo> authorInfos = new HashMap<>();
+			for (AuthorId id : authors) {
+				authorInfos.put(id, authorManager.getAuthorInfo(txn, id));
+			}
+			// Parse the metadata
+			for (Entry<MessageId, BdfDictionary> entry : metadata.entrySet()) {
+				BdfDictionary meta = entry.getValue();
+				headers.add(getForumPostHeader(txn, entry.getKey(), meta,
+						authorInfos));
+			}
+			return headers;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}

briar-core/src/main/java/org/briarproject/briar/privategroup/PrivateGroupManagerImpl.java

@@ -145,7 +145,7 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 		addMember(txn, m.getMessage().getGroupId(), m.getMember(), VISIBLE);
 		setPreviousMsgId(txn, m.getMessage().getGroupId(),
 				m.getMessage().getId());
-		attachJoinMessageAddedEvent(txn, m.getMessage(), meta, true, VISIBLE);
+		attachJoinMessageAddedEvent(txn, m.getMessage(), meta, true);
 	}
 
 	@Override
@@ -210,34 +210,35 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 	@Override
 	public GroupMessageHeader addLocalMessage(GroupMessage m)
 			throws DbException {
-		return db.transactionWithResult(false, txn -> {
-			try {
-				return addLocalMessage(txn, m);
-			} catch (FormatException e) {
-				throw new DbException(e);
-			}
-		});
+		return db.transactionWithResult(false, txn -> addLocalMessage(txn, m));
 	}
 
-	private GroupMessageHeader addLocalMessage(Transaction txn, GroupMessage m)
-			throws DbException, FormatException {
-		// store message and metadata
-		BdfDictionary meta = new BdfDictionary();
-		meta.put(KEY_TYPE, POST.getInt());
-		if (m.getParent() != null)
-			meta.put(KEY_PARENT_MSG_ID, m.getParent());
-		addMessageMetadata(meta, m);
-		GroupId g = m.getMessage().getGroupId();
-		clientHelper.addLocalMessage(txn, m.getMessage(), meta, true, false);
-		// track message
-		setPreviousMsgId(txn, g, m.getMessage().getId());
-		messageTracker.trackOutgoingMessage(txn, m.getMessage());
-		// broadcast event
-		attachGroupMessageAddedEvent(txn, m.getMessage(), meta, true);
-		AuthorInfo authorInfo = authorManager.getMyAuthorInfo(txn);
-		return new GroupMessageHeader(m.getMessage().getGroupId(),
-				m.getMessage().getId(), m.getParent(),
-				m.getMessage().getTimestamp(), m.getMember(), authorInfo, true);
+	@Override
+	public GroupMessageHeader addLocalMessage(Transaction txn, GroupMessage m)
+			throws DbException {
+		try {
+			// store message and metadata
+			BdfDictionary meta = new BdfDictionary();
+			meta.put(KEY_TYPE, POST.getInt());
+			if (m.getParent() != null)
+				meta.put(KEY_PARENT_MSG_ID, m.getParent());
+			addMessageMetadata(meta, m);
+			GroupId g = m.getMessage().getGroupId();
+			clientHelper
+					.addLocalMessage(txn, m.getMessage(), meta, true, false);
+			// track message
+			setPreviousMsgId(txn, g, m.getMessage().getId());
+			messageTracker.trackOutgoingMessage(txn, m.getMessage());
+			// broadcast event
+			attachGroupMessageAddedEvent(txn, m.getMessage(), meta, true);
+			AuthorInfo authorInfo = authorManager.getMyAuthorInfo(txn);
+			return new GroupMessageHeader(m.getMessage().getGroupId(),
+					m.getMessage().getId(), m.getParent(),
+					m.getMessage().getTimestamp(), m.getMember(), authorInfo,
+					true);
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
 	}
 
 	private void addMessageMetadata(BdfDictionary meta, GroupMessage m) {
@@ -315,6 +316,16 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
+	@Override
+	public String getMessageText(Transaction txn, MessageId m)
+			throws DbException {
+		try {
+			return getMessageText(clientHelper.getMessageAsList(txn, m));
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	private String getMessageText(BdfList body) throws FormatException {
 		// Message type (0), member (1), parent ID (2), previous message ID (3),
 		// text (4), signature (5)
@@ -324,8 +335,13 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 	@Override
 	public Collection<GroupMessageHeader> getHeaders(GroupId g)
 			throws DbException {
-		Collection<GroupMessageHeader> headers = new ArrayList<>();
-		Transaction txn = db.startTransaction(true);
+		return db.transactionWithResult(true, txn -> getHeaders(txn, g));
+	}
+
+	@Override
+	public List<GroupMessageHeader> getHeaders(Transaction txn, GroupId g)
+			throws DbException {
+		List<GroupMessageHeader> headers = new ArrayList<>();
 		try {
 			Map<MessageId, BdfDictionary> metadata =
 					clientHelper.getMessageMetadataAsDictionary(txn, g);
@@ -339,27 +355,20 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 			for (AuthorId id : authors) {
 				authorInfos.put(id, authorManager.getAuthorInfo(txn, id));
 			}
-			// get current visibilities for join messages
-			Map<Author, Visibility> visibilities = getMembers(txn, g);
 			// parse the metadata
 			for (Entry<MessageId, BdfDictionary> entry : metadata.entrySet()) {
 				BdfDictionary meta = entry.getValue();
 				if (meta.getLong(KEY_TYPE) == JOIN.getInt()) {
-					Author member = getAuthor(meta);
-					Visibility v = visibilities.get(member);
 					headers.add(getJoinMessageHeader(txn, g, entry.getKey(),
-							meta, authorInfos, v));
+							meta, authorInfos));
 				} else {
 					headers.add(getGroupMessageHeader(txn, g, entry.getKey(),
 							meta, authorInfos));
 				}
 			}
-			db.commitTransaction(txn);
 			return headers;
 		} catch (FormatException e) {
 			throw new DbException(e);
-		} finally {
-			db.endTransaction(txn);
 		}
 	}
 
@@ -389,46 +398,45 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 
 	private JoinMessageHeader getJoinMessageHeader(Transaction txn, GroupId g,
 			MessageId id, BdfDictionary meta,
-			Map<AuthorId, AuthorInfo> authorInfos, Visibility v)
+			Map<AuthorId, AuthorInfo> authorInfos)
 			throws DbException, FormatException {
 
 		GroupMessageHeader header =
 				getGroupMessageHeader(txn, g, id, meta, authorInfos);
 		boolean creator = meta.getBoolean(KEY_INITIAL_JOIN_MSG);
-		return new JoinMessageHeader(header, v, creator);
+		return new JoinMessageHeader(header, creator);
 	}
 
 	@Override
 	public Collection<GroupMember> getMembers(GroupId g) throws DbException {
-		Transaction txn = db.startTransaction(true);
-		try {
-			Collection<GroupMember> members = new ArrayList<>();
-			Map<Author, Visibility> authors = getMembers(txn, g);
-			LocalAuthor la = identityManager.getLocalAuthor(txn);
-			PrivateGroup privateGroup = getPrivateGroup(txn, g);
-			for (Entry<Author, Visibility> m : authors.entrySet()) {
-				Author a = m.getKey();
-				AuthorInfo authorInfo =
-						authorManager.getAuthorInfo(txn, a.getId());
-				Status status = authorInfo.getStatus();
-				Visibility v = m.getValue();
-				ContactId c = null;
-				if (v != INVISIBLE &&
-						(status == VERIFIED || status == UNVERIFIED)) {
-					c = contactManager.getContact(txn, a.getId(), la.getId())
-							.getId();
-				}
-				boolean isCreator = privateGroup.getCreator().equals(a);
-				members.add(new GroupMember(a, authorInfo, isCreator, c, v));
-			}
-			db.commitTransaction(txn);
-			return members;
-		} finally {
-			db.endTransaction(txn);
-		}
+		return db.transactionWithResult(true, txn -> getMembers(txn, g));
 	}
 
-	private Map<Author, Visibility> getMembers(Transaction txn, GroupId g)
+	@Override
+	public Collection<GroupMember> getMembers(Transaction txn, GroupId g)
+			throws DbException {
+		Collection<GroupMember> members = new ArrayList<>();
+		Map<Author, Visibility> authors = getMemberAuthors(txn, g);
+		LocalAuthor la = identityManager.getLocalAuthor(txn);
+		PrivateGroup privateGroup = getPrivateGroup(txn, g);
+		for (Entry<Author, Visibility> m : authors.entrySet()) {
+			Author a = m.getKey();
+			AuthorInfo authorInfo = authorManager.getAuthorInfo(txn, a.getId());
+			Status status = authorInfo.getStatus();
+			Visibility v = m.getValue();
+			ContactId c = null;
+			if (v != INVISIBLE &&
+					(status == VERIFIED || status == UNVERIFIED)) {
+				c = contactManager.getContact(txn, a.getId(), la.getId())
+						.getId();
+			}
+			boolean isCreator = privateGroup.getCreator().equals(a);
+			members.add(new GroupMember(a, authorInfo, isCreator, c, v));
+		}
+		return members;
+	}
+
+	private Map<Author, Visibility> getMemberAuthors(Transaction txn, GroupId g)
 			throws DbException {
 		try {
 			BdfDictionary meta =
@@ -450,7 +458,7 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 	@Override
 	public boolean isMember(Transaction txn, GroupId g, Author a)
 			throws DbException {
-		for (Author member : getMembers(txn, g).keySet()) {
+		for (Author member : getMemberAuthors(txn, g).keySet()) {
 			if (member.equals(a)) return true;
 		}
 		return false;
@@ -544,7 +552,7 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 		addMember(txn, m.getGroupId(), member, v);
 		// track message and broadcast event
 		messageTracker.trackIncomingMessage(txn, m);
-		attachJoinMessageAddedEvent(txn, m, meta, false, v);
+		attachJoinMessageAddedEvent(txn, m, meta, false);
 	}
 
 	private void handleGroupMessage(Transaction txn, Message m,
@@ -594,10 +602,10 @@ class PrivateGroupManagerImpl extends BdfIncomingMessageHook
 	}
 
 	private void attachJoinMessageAddedEvent(Transaction txn, Message m,
-			BdfDictionary meta, boolean local, Visibility v)
+			BdfDictionary meta, boolean local)
 			throws DbException, FormatException {
 		JoinMessageHeader header = getJoinMessageHeader(txn, m.getGroupId(),
-				m.getId(), meta, Collections.emptyMap(), v);
+				m.getId(), meta, Collections.emptyMap());
 		txn.attach(new GroupMessageAddedEvent(m.getGroupId(), header, "",
 				local));
 	}

briar-core/src/main/java/org/briarproject/briar/sharing/SharingManagerImpl.java

@@ -426,17 +426,17 @@ abstract class SharingManagerImpl<S extends Shareable>
 
 	@Override
 	public Collection<Contact> getSharedWith(GroupId g) throws DbException {
+		return db.transactionWithResult(true, txn -> getSharedWith(txn, g));
+	}
+
+	@Override
+	public Collection<Contact> getSharedWith(Transaction txn, GroupId g)
+			throws DbException {
 		// TODO report also pending invitations
 		Collection<Contact> contacts = new ArrayList<>();
-		Transaction txn = db.startTransaction(true);
-		try {
-			for (Contact c : db.getContacts(txn)) {
-				if (db.getGroupVisibility(txn, c.getId(), g) == SHARED)
-					contacts.add(c);
-			}
-			db.commitTransaction(txn);
-		} finally {
-			db.endTransaction(txn);
+		for (Contact c : db.getContacts(txn)) {
+			if (db.getGroupVisibility(txn, c.getId(), g) == SHARED)
+				contacts.add(c);
 		}
 		return contacts;
 	}

briar-core/src/test/java/org/briarproject/briar/privategroup/PrivateGroupManagerIntegrationTest.java

@@ -124,10 +124,8 @@ public class PrivateGroupManagerIntegrationTest
 		addGroup();
 
 		// create and add test message with no previousMsgId
-		@SuppressWarnings("ConstantConditions")
-		GroupMessage msg = groupMessageFactory
-				.createGroupMessage(groupId0, clock.currentTimeMillis(), null,
-						author0, "test", null);
+		GroupMessage msg = groupMessageFactory.createGroupMessage(groupId0,
+				clock.currentTimeMillis(), null, author0, "test", null);
 		groupManager0.addLocalMessage(msg);
 
 		// sync test message
@@ -342,52 +340,19 @@ public class PrivateGroupManagerIntegrationTest
 		Collection<GroupMember> members0 = groupManager0.getMembers(groupId0);
 		assertEquals(2, members0.size());
 		for (GroupMember m : members0) {
-			if (m.getAuthor().equals(author0)) {
-				assertEquals(VISIBLE, m.getVisibility());
-			} else {
+			if (!m.getAuthor().equals(author0)) {
 				assertEquals(author1, m.getAuthor());
-				assertEquals(VISIBLE, m.getVisibility());
 			}
+			assertEquals(VISIBLE, m.getVisibility());
 		}
 
 		Collection<GroupMember> members1 = groupManager1.getMembers(groupId0);
 		assertEquals(2, members1.size());
 		for (GroupMember m : members1) {
-			if (m.getAuthor().equals(author1)) {
-				assertEquals(VISIBLE, m.getVisibility());
-			} else {
+			if (!m.getAuthor().equals(author1)) {
 				assertEquals(author0, m.getAuthor());
-				assertEquals(VISIBLE, m.getVisibility());
-			}
-		}
-	}
-
-	@Test
-	public void testJoinMessages() throws Exception {
-		addGroup();
-
-		Collection<GroupMessageHeader> headers0 =
-				groupManager0.getHeaders(groupId0);
-		for (GroupMessageHeader h : headers0) {
-			if (h instanceof JoinMessageHeader) {
-				JoinMessageHeader j = (JoinMessageHeader) h;
-				// all relationships of the creator are visible
-				assertEquals(VISIBLE, j.getVisibility());
-			}
-		}
-
-		Collection<GroupMessageHeader> headers1 =
-				groupManager1.getHeaders(groupId0);
-		for (GroupMessageHeader h : headers1) {
-			if (h instanceof JoinMessageHeader) {
-				JoinMessageHeader j = (JoinMessageHeader) h;
-				if (h.getAuthor().equals(author1))
-					// we are visible to ourselves
-					assertEquals(VISIBLE, j.getVisibility());
-				else
-					// our relationship to the creator is visible
-					assertEquals(VISIBLE, j.getVisibility());
 			}
+			assertEquals(VISIBLE, m.getVisibility());
 		}
 	}
 
@@ -463,34 +428,6 @@ public class PrivateGroupManagerIntegrationTest
 				assertEquals(REVEALED_BY_CONTACT, m.getVisibility());
 			}
 		}
-
-		// assert that join messages reflect revealed relationship
-		Collection<GroupMessageHeader> headers1 =
-				groupManager1.getHeaders(groupId0);
-		for (GroupMessageHeader h : headers1) {
-			if (h instanceof JoinMessageHeader) {
-				JoinMessageHeader j = (JoinMessageHeader) h;
-				if (h.getAuthor().equals(author2))
-					// 1 revealed the relationship to 2
-					assertEquals(REVEALED_BY_US, j.getVisibility());
-				else
-					// 1's other relationship (to 1 and creator) are visible
-					assertEquals(VISIBLE, j.getVisibility());
-			}
-		}
-		Collection<GroupMessageHeader> headers2 =
-				groupManager2.getHeaders(groupId0);
-		for (GroupMessageHeader h : headers2) {
-			if (h instanceof JoinMessageHeader) {
-				JoinMessageHeader j = (JoinMessageHeader) h;
-				if (h.getAuthor().equals(author1))
-					// 2's relationship was revealed by 1
-					assertEquals(REVEALED_BY_CONTACT, j.getVisibility());
-				else
-					// 2's other relationship (to 2 and creator) are visible
-					assertEquals(VISIBLE, j.getVisibility());
-			}
-		}
 	}
 
 	@Test