Move adding new ThreadList items to ViewModel

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

@@ -8,20 +8,15 @@ 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.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;
@@ -33,16 +28,13 @@ 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
+class ForumControllerImpl extends ThreadListControllerImpl<ForumPostItem>
-		ThreadListControllerImpl<ForumPostItem, ForumPostHeader, ForumPost, ForumListener>
 		implements ForumController {
 
 	private static final Logger LOG =
@@ -56,10 +48,10 @@ class ForumControllerImpl extends
 			LifecycleManager lifecycleManager, IdentityManager identityManager,
 			@CryptoExecutor Executor cryptoExecutor,
 			ForumManager forumManager, ForumSharingManager forumSharingManager,
-			EventBus eventBus, Clock clock, MessageTracker messageTracker,
+			EventBus eventBus, Clock clock,
 			AndroidNotificationManager notificationManager) {
 		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
+				eventBus, clock, notificationManager);
 		this.forumManager = forumManager;
 		this.forumSharingManager = forumSharingManager;
 	}
@@ -74,6 +66,8 @@ class ForumControllerImpl extends
 	public void eventOccurred(Event e) {
 		super.eventOccurred(e);
 
+		ForumListener listener = (ForumListener) this.listener;
+
 		if (e instanceof ForumPostReceivedEvent) {
 			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
 			if (f.getGroupId().equals(getGroupId())) {
@@ -120,44 +114,7 @@ class ForumControllerImpl extends
 		});
 	}
 
-	@Override
+	private ForumPostItem buildItem(ForumPostHeader header, String text) {
-	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 ForumPostItem buildItem(ForumPostHeader header, String text) {
 		return new ForumPostItem(header, text);
 	}
 

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

@@ -11,32 +11,37 @@ 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.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.client.PostHeader;
 import org.briarproject.briar.api.forum.Forum;
 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.client.MessageTreeImpl;
 
 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;
@@ -98,12 +103,52 @@ class ForumViewModel extends ThreadListViewModel<ForumPostItem> {
 			List<ForumPostHeader> headers =
 					forumManager.getPostHeaders(txn, groupId);
 			logDuration(LOG, "Loading headers", start);
-			List<ForumPostItem> items =
+			return recreateItems(txn, headers, this::buildItem);
-					buildItems(txn, headers, this::buildItem);
-			return new MessageTreeImpl<>(items).depthFirstOrder();
 		}, this::setItems);
 	}
 
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable ForumPostItem parentItem) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				GroupCount count = forumManager.getGroupCount(groupId);
+				long timestamp = max(count.getLatestMsgTime() + 1,
+						clock.currentTimeMillis());
+				MessageId parentId =
+						parentItem != null ? parentItem.getId() : null;
+				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(() -> {
+			try {
+				long start = now();
+				ForumPostHeader header = forumManager.addLocalPost(msg);
+				textCache.put(msg.getMessage().getId(), text);
+				addItem(buildItem(header, text), true);
+				logDuration(LOG, "Storing forum post", start);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
 	private ForumPostItem buildItem(ForumPostHeader header, String text) {
 		return new ForumPostItem(header, text);
 	}

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

@@ -7,21 +7,15 @@ 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.PrivateGroupManager;
@@ -36,37 +30,32 @@ 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 java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class GroupControllerImpl extends
+class GroupControllerImpl extends ThreadListControllerImpl<GroupMessageItem>
-		ThreadListControllerImpl<GroupMessageItem, GroupMessageHeader, GroupMessage, GroupListener>
 		implements GroupController {
 
 	private static final Logger LOG =
-			Logger.getLogger(GroupControllerImpl.class.getName());
+			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,
+			EventBus eventBus, Clock clock,
-			MessageTracker messageTracker, Clock clock,
 			AndroidNotificationManager notificationManager) {
 		super(dbExecutor, lifecycleManager, identityManager, cryptoExecutor,
-				eventBus, clock, notificationManager, messageTracker);
+				eventBus, clock, notificationManager);
 		this.privateGroupManager = privateGroupManager;
-		this.groupMessageFactory = groupMessageFactory;
 	}
 
 	@Override
@@ -79,6 +68,8 @@ class GroupControllerImpl extends
 	public void eventOccurred(Event e) {
 		super.eventOccurred(e);
 
+		GroupListener listener = (GroupListener) this.listener;
+
 		if (e instanceof GroupMessageAddedEvent) {
 			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
 			if (!g.isLocal() && g.getGroupId().equals(getGroupId())) {
@@ -132,52 +123,7 @@ class GroupControllerImpl extends
 		});
 	}
 
-	@Override
+	private GroupMessageItem buildItem(GroupMessageHeader header, String text) {
-	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 GroupMessageItem buildItem(GroupMessageHeader header,
-			String text) {
 		if (header instanceof JoinMessageHeader) {
 			return new JoinMessageItem((JoinMessageHeader) header, text);
 		}

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

@@ -58,7 +58,7 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 			GroupMessageItem item = getItem(position);
 			if (item instanceof JoinMessageItem) {
 				((JoinMessageItem) item).setVisibility(v);
-				notifyItemChanged(findItemPosition(item), item);
+				notifyItemChanged(findItemPosition(item.getId()), item);
 			}
 		}
 	}
@@ -73,12 +73,4 @@ class GroupMessageAdapter extends ThreadItemAdapter<GroupMessageItem> {
 		return NO_POSITION; // Not found
 	}
 
-	@Deprecated
-	private int findItemPosition(GroupMessageItem itemToFind) {
-		for (int i = 0; i < getItemCount(); i++) {
-			if (getItem(i).equals(itemToFind)) return i;
-		}
-		return NO_POSITION; // Not found
-	}
-
 }

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

@@ -11,32 +11,37 @@ 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.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.client.PostHeader;
+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.client.MessageTreeImpl;
 
 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;
@@ -109,9 +114,7 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 			List<GroupMessageHeader> headers =
 					privateGroupManager.getHeaders(txn, groupId);
 			logDuration(LOG, "Loading headers", start);
-			List<GroupMessageItem> items =
+			return recreateItems(txn, headers, this::buildItem);
-					buildItems(txn, headers, this::buildItem);
-			return new MessageTreeImpl<>(items).depthFirstOrder();
 		}, this::setItems);
 	}
 
@@ -132,6 +135,52 @@ class GroupViewModel extends ThreadListViewModel<GroupMessageItem> {
 		return privateGroupManager.getMessageText(txn, header.getId());
 	}
 
+	@Override
+	public void createAndStoreMessage(String text,
+			@Nullable GroupMessageItem parentItem) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor author = identityManager.getLocalAuthor();
+				MessageId parentId = null;
+				MessageId previousMsgId =
+						privateGroupManager.getPreviousMsgId(groupId);
+				GroupCount count = privateGroupManager.getGroupCount(groupId);
+				long timestamp = count.getLatestMsgTime();
+				if (parentItem != null) parentId = parentItem.getId();
+				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(() -> {
+			try {
+				long start = now();
+				GroupMessageHeader header =
+						privateGroupManager.addLocalMessage(msg);
+				textCache.put(msg.getMessage().getId(), text);
+				addItem(buildItem(header, text), true);
+				logDuration(LOG, "Storing group message", start);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
 	void deletePrivateGroup() {
 		runOnDbThread(() -> {
 			try {

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

@@ -66,16 +66,11 @@ public class ThreadItemAdapter<I extends ThreadItem>
 		ui.bind(item, listener);
 	}
 
-	void setItemWithIdVisible(MessageId messageId) {
+	public int findItemPosition(MessageId id) {
-		int pos = 0;
 		for (int i = 0; i < getItemCount(); i++) {
-			I item = getItem(i);
+			if (id.equals(getItem(i).getId())) return i;
-			if (item.getId().equals(messageId)) {
-				layoutManager.scrollToPosition(pos);
-				break;
-			}
-			pos++;
 		}
+		return NO_POSITION; // Not found
 	}
 
 	/**

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

@@ -136,6 +136,12 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		loadSharingContacts();
 	}
 
+	@Override
+	protected void onDestroy() {
+		super.onDestroy();
+		getViewModel().storeMessageId(getFirstVisibleMessageId());
+	}
+
 	@Override
 	@Nullable
 	public MessageId getFirstVisibleMessageId() {
@@ -154,21 +160,29 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		if (items.isEmpty()) {
 			list.showData();
 		} else {
-			adapter.submitList(items);
+			adapter.submitList(items, this::scrollAfterListCommitted);
-			// TODO get this ID from elsewhere
-			MessageId messageId = null; // items.getFirstVisibleItemId();
-			if (messageId != null)
-				adapter.setItemWithIdVisible(messageId);
-			list.showData();
-			if (layoutManagerState == null) {
-				list.scrollToPosition(0);  // Scroll to the top
-			} else {
-				layoutManager.onRestoreInstanceState(layoutManagerState);
-			}
 			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);
+	}
+
 	protected void loadSharingContacts() {
 		getController().loadSharingContacts(
 				new UiResultExceptionHandler<Collection<ContactId>, DbException>(
@@ -206,10 +220,6 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 	@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());
 		}
@@ -218,7 +228,6 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 	@Override
 	protected void onRestoreInstanceState(Bundle savedInstanceState) {
 		super.onRestoreInstanceState(savedInstanceState);
-		layoutManagerState = savedInstanceState.getParcelable("layoutManager");
 	}
 
 	@Override
@@ -247,11 +256,11 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		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);
 			});
 		}
@@ -277,11 +286,10 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		}
 	}
 
-	private void scrollToItemAtTop(I item) {
+	private void scrollToItemAtTop(MessageId messageId) {
-		int position = NO_POSITION;// adapter.findItemPosition(item);
+		int position = adapter.findItemPosition(messageId);
 		if (position != NO_POSITION) {
-			layoutManager
+			layoutManager.scrollToPositionWithOffset(position, 0);
-					.scrollToPositionWithOffset(position, 0);
 		}
 	}
 
@@ -307,19 +315,7 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		if (isNullOrEmpty(text)) throw new AssertionError();
 
 		I replyItem = adapter.getHighlightedItem();
-		UiResultExceptionHandler<I, DbException> handler =
+		getViewModel().createAndStoreMessage(text, replyItem);
-				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);
 		textInput.hideSoftKeyboard();
 		textInput.clearText();
 		replyId = null;
@@ -330,7 +326,7 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 
 	@Override
 	public void onItemReceived(I item) {
-		addItem(item, false);
+		getViewModel().addItem(item, false);
 	}
 
 	@Override
@@ -338,21 +334,4 @@ public abstract class ThreadListActivity<I extends ThreadItem, A extends ThreadI
 		supportFinishAfterTransition();
 	}
 
-	private void addItem(I item, boolean isLocal) {
-		MessageId parent = item.getParentId();
-		if (parent != null) {
-			// 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;
-		}
-		// TODO submit new list
-
-		if (isLocal) {
-			scrollToItemAtTop(item);
-		} else {
-			scrollListener.updateUnreadButtons(layoutManager);
-		}
-	}
-
 }

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

@@ -27,9 +27,6 @@ public interface ThreadListController<I extends ThreadItem>
 
 	void markItemsRead(Collection<I> items);
 
-	void createAndStoreMessage(String text, @Nullable I parentItem,
-			ResultExceptionHandler<I, DbException> handler);
-
 	interface ThreadListListener<I> extends ThreadListDataSource {
 
 		@UiThread

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

@@ -17,17 +17,10 @@ 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.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.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;
 
@@ -40,39 +33,34 @@ import static org.briarproject.bramble.util.LogUtils.now;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public abstract class ThreadListControllerImpl<I extends ThreadItem, H extends PostHeader, M extends ThreadedMessage, L extends ThreadListListener<I>>
+public abstract class ThreadListControllerImpl<I extends ThreadItem>
 		extends DbControllerImpl
 		implements ThreadListController<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;
 
+	private final EventBus eventBus;
 	protected final IdentityManager identityManager;
 	protected final AndroidNotificationManager notificationManager;
 	protected final Executor cryptoExecutor;
 	protected final Clock clock;
 
 	// UI thread
-	protected L listener;
+	protected ThreadListListener<I> listener;
 
 	protected ThreadListControllerImpl(@DatabaseExecutor Executor dbExecutor,
 			LifecycleManager lifecycleManager, IdentityManager identityManager,
 			@CryptoExecutor Executor cryptoExecutor, EventBus eventBus,
-			Clock clock, AndroidNotificationManager notificationManager,
+			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
@@ -84,7 +72,7 @@ public abstract class ThreadListControllerImpl<I extends ThreadItem, H extends P
 	@SuppressWarnings("unchecked")
 	@Override
 	public void onActivityCreate(Activity activity) {
-		listener = (L) activity;
+		listener = (ThreadListListener<I>) activity;
 	}
 
 	@CallSuper
@@ -103,16 +91,7 @@ public abstract class ThreadListControllerImpl<I extends ThreadItem, H extends P
 
 	@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
@@ -150,27 +129,6 @@ public abstract class ThreadListControllerImpl<I extends ThreadItem, H extends P
 	@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;
-
-	protected abstract I buildItem(H header, String text);
-
 	protected GroupId getGroupId() {
 		checkGroupId();
 		return groupId;

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

@@ -21,28 +21,36 @@ 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.api.client.PostHeader;
+import org.briarproject.briar.client.MessageTreeImpl;
 
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 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.logging.Level.INFO;
+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
-public abstract class ThreadListViewModel<I extends ThreadItem> extends DbViewModel
+public abstract class ThreadListViewModel<I extends ThreadItem>
+		extends DbViewModel
 		implements EventListener {
 
 	private static final Logger LOG =
@@ -55,11 +63,18 @@ public abstract class ThreadListViewModel<I extends ThreadItem> extends DbViewMo
 	private final MessageTracker messageTracker;
 	private final EventBus eventBus;
 
-	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	@DatabaseExecutor
+	private final MessageTree<I> messageTree = new MessageTreeImpl<>();
+	protected final Map<MessageId, String> textCache =
+			new ConcurrentHashMap<>();
 	private final MutableLiveData<LiveResult<List<I>>> items =
 			new MutableLiveData<>();
+	private final AtomicReference<MessageId> scrollToItem =
+			new AtomicReference<>();
 
 	protected volatile GroupId groupId;
+	private final AtomicReference<MessageId> storedMessageId =
+			new AtomicReference<>();
 
 	public ThreadListViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
@@ -95,18 +110,37 @@ public abstract class ThreadListViewModel<I extends ThreadItem> extends DbViewMo
 	@CallSuper
 	public void setGroupId(GroupId groupId) {
 		this.groupId = groupId;
+		loadStoredMessageId();
 		loadItems();
 	}
 
+	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 I parentItem);
+
 	@UiThread
 	protected void setItems(LiveResult<List<I>> items) {
 		this.items.setValue(items);
 	}
 
 	@DatabaseExecutor
-	protected <H extends PostHeader> List<I> buildItems(
+	protected <H extends PostHeader> List<I> recreateItems(
 			Transaction txn, Collection<H> headers, ItemGetter<H, I> itemGetter)
 			throws DbException {
 		long start = now();
@@ -122,23 +156,45 @@ public abstract class ThreadListViewModel<I extends ThreadItem> extends DbViewMo
 		}
 		logDuration(LOG, "Loading bodies and creating items", start);
 
-		MessageId msgId = messageTracker.loadStoredMessageId(txn, groupId);
+		messageTree.clear();
-		if (LOG.isLoggable(INFO)) {
+		messageTree.add(items);
-			LOG.info("Loaded last top visible message id " + msgId);
+		return messageTree.depthFirstOrder();
-		}
+	}
-		// TODO store this elsewhere
+
-		items.setFirstVisibleId(msgId);
+	protected void addItem(I item, boolean local) {
-		return items;
+		messageTree.add(item);
+		if (local) scrollToItem.set(item.getId());
+		items.postValue(new LiveResult<>(messageTree.depthFirstOrder()));
 	}
 
 	@DatabaseExecutor
 	protected abstract String loadMessageText(Transaction txn,
 			PostHeader header) throws DbException;
 
+	void storeMessageId(@Nullable MessageId messageId) {
+		if (messageId != null) runOnDbThread(() -> {
+			try {
+				messageTracker.storeMessageId(groupId, messageId);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@Nullable
+	MessageId getAndResetRestoredMessageId() {
+		return storedMessageId.getAndSet(null);
+	}
+
 	LiveData<LiveResult<List<I>>> getItems() {
 		return items;
 	}
 
+	@Nullable
+	MessageId getAndResetScrollToItem() {
+		return scrollToItem.getAndSet(null);
+	}
+
 	public interface ItemGetter<H extends PostHeader, I> {
 		I getItem(H header, String text);
 	}

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

@@ -13,15 +13,12 @@ public interface MessageTree<T extends MessageTree.MessageNode> {
 
 	void add(Collection<T> nodes);
 
-	@Deprecated
 	void add(T node);
 
-	@Deprecated
 	void clear();
 
 	List<T> depthFirstOrder();
 
-	@Deprecated
 	boolean contains(MessageId m);
 
 	@NotNullByDefault

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

@@ -109,7 +109,6 @@ public interface ForumManager {
 	/**
 	 * Returns the group count for the given forum.
 	 */
-	@Deprecated
 	GroupCount getGroupCount(GroupId g) throws DbException;
 
 	/**

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

@@ -33,11 +33,6 @@ public class MessageTreeImpl<T extends MessageTree.MessageNode>
 	private final Comparator<T> comparator = (o1, o2) ->
 			Long.valueOf(o1.getTimestamp()).compareTo(o2.getTimestamp());
 
-	public MessageTreeImpl(Collection<T> collection) {
-		super();
-		add(collection);
-	}
-
 	@Override
 	public synchronized void clear() {
 		roots.clear();