Turn FeedController into FeedViewModel

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

@@ -30,6 +30,7 @@ import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.DozeHelperModule;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.account.SetupModule;
+import org.briarproject.briar.android.blog.BlogModule;
 import org.briarproject.briar.android.contact.ContactListModule;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
@@ -85,6 +86,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		ContactListModule.class,
 		IntroductionModule.class,
 		// below need to be within same scope as ViewModelProvider.Factory
+		BlogModule.BindsModule.class,
 		ForumModule.class,
 		GroupListModule.class,
 		GroupConversationModule.class,

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseController.java

@@ -8,7 +8,7 @@ import org.briarproject.briar.android.controller.handler.ExceptionHandler;
 import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 import org.briarproject.briar.api.blog.BlogPostHeader;
 
-import java.util.Collection;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -24,7 +24,7 @@ interface BaseController {
 	void onStop();
 
 	void loadBlogPosts(GroupId g,
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+			ResultExceptionHandler<List<BlogPostItem>, DbException> handler);
 
 	void loadBlogPost(BlogPostHeader header,
 			ResultExceptionHandler<BlogPostItem, DbException> handler);

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseControllerImpl.java

@@ -23,6 +23,7 @@ import org.briarproject.briar.util.HtmlUtils;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.Executor;
@@ -80,10 +81,10 @@ abstract class BaseControllerImpl extends DbControllerImpl
 
 	@Override
 	public void loadBlogPosts(GroupId groupId,
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+			ResultExceptionHandler<List<BlogPostItem>, DbException> handler) {
 		runOnDbThread(() -> {
 			try {
-				Collection<BlogPostItem> items = loadItems(groupId);
+				List<BlogPostItem> items = loadItems(groupId);
 				handler.onResult(items);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
@@ -92,12 +93,12 @@ abstract class BaseControllerImpl extends DbControllerImpl
 		});
 	}
 
-	Collection<BlogPostItem> loadItems(GroupId groupId) throws DbException {
+	List<BlogPostItem> loadItems(GroupId groupId) throws DbException {
 		long start = now();
 		Collection<BlogPostHeader> headers =
 				blogManager.getPostHeaders(groupId);
 		logDuration(LOG, "Loading headers", start);
-		Collection<BlogPostItem> items = new ArrayList<>(headers.size());
+		List<BlogPostItem> items = new ArrayList<>(headers.size());
 		start = now();
 		for (BlogPostHeader h : headers) {
 			headerCache.put(h.getId(), h);

briar-android/src/main/java/org/briarproject/briar/android/blog/BaseViewModel.java

@@ -0,0 +1,219 @@
+package org.briarproject.briar.android.blog;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
+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.event.EventListener;
+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.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogCommentHeader;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.util.HtmlUtils;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+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 androidx.lifecycle.Transformations;
+
+import static java.util.Objects.requireNonNull;
+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;
+import static org.briarproject.briar.util.HtmlUtils.ARTICLE;
+
+@NotNullByDefault
+public class BaseViewModel extends DbViewModel implements EventListener {
+
+	private static Logger LOG = getLogger(BaseViewModel.class.getName());
+
+	protected final TransactionManager db;
+	private final EventBus eventBus;
+	protected final IdentityManager identityManager;
+	protected final BlogManager blogManager;
+
+	protected final MutableLiveData<LiveResult<List<BlogPostItem>>> blogPosts =
+			new MutableLiveData<>();
+
+	// TODO do we still need those caches?
+	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private final Map<MessageId, BlogPostHeader> headerCache =
+			new ConcurrentHashMap<>();
+
+	@Inject
+	BaseViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			BlogManager blogManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.db = db;
+		this.eventBus = eventBus;
+		this.identityManager = identityManager;
+		this.blogManager = blogManager;
+
+		eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+	}
+
+	void loadItems(GroupId groupId) {
+		loadList(txn -> loadBlogPosts(txn, groupId), blogPosts::setValue);
+	}
+
+	@DatabaseExecutor
+	protected List<BlogPostItem> loadBlogPosts(Transaction txn, GroupId groupId)
+			throws DbException {
+		long start = now();
+		List<BlogPostHeader> headers =
+				blogManager.getPostHeaders(txn, groupId);
+		logDuration(LOG, "Loading headers", start);
+		List<BlogPostItem> items = new ArrayList<>(headers.size());
+		start = now();
+		for (BlogPostHeader h : headers) {
+			headerCache.put(h.getId(), h);
+			BlogPostItem item = getItem(txn, h);
+			items.add(item);
+		}
+		logDuration(LOG, "Loading bodies", start);
+		return items;
+	}
+
+	@DatabaseExecutor
+	protected BlogPostItem getItem(Transaction txn, BlogPostHeader h)
+			throws DbException {
+		String text;
+		if (h instanceof BlogCommentHeader) {
+			BlogCommentHeader c = (BlogCommentHeader) h;
+			BlogCommentItem item = new BlogCommentItem(c);
+			text = getPostText(txn, item.getPostHeader().getId());
+			item.setText(text);
+			return item;
+		} else {
+			text = getPostText(txn, h.getId());
+			return new BlogPostItem(h, text);
+		}
+	}
+
+	@DatabaseExecutor
+	private String getPostText(Transaction txn, MessageId m)
+			throws DbException {
+		String text = textCache.get(m);
+		if (text == null) {
+			text = HtmlUtils.clean(blogManager.getPostText(txn, m), ARTICLE);
+			textCache.put(m, text);
+		}
+		return text;
+	}
+
+	LiveData<LiveResult<BlogPostItem>> loadBlogPost(GroupId g, MessageId m) {
+		MutableLiveData<LiveResult<BlogPostItem>> result =
+				new MutableLiveData<>();
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				BlogPostHeader header1 = getPostHeader(g, m);
+				BlogPostItem item = db.transactionWithResult(true, txn ->
+						getItem(txn, header1)
+				);
+				logDuration(LOG, "Loading post", start);
+				result.postValue(new LiveResult<>(item));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				result.postValue(new LiveResult<>(e));
+			}
+		});
+		return result;
+	}
+
+	@DatabaseExecutor
+	private BlogPostHeader getPostHeader(GroupId g, MessageId m)
+			throws DbException {
+		BlogPostHeader header = headerCache.get(m);
+		if (header == null) {
+			header = blogManager.getPostHeader(g, m);
+			headerCache.put(m, header);
+		}
+		return header;
+	}
+
+	void repeatPost(BlogPostItem item, @Nullable String comment) {
+		runOnDbThread(() -> {
+			try {
+				LocalAuthor a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				BlogPostHeader h = item.getHeader();
+				blogManager.addLocalComment(a, b.getId(), comment, h);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<LiveResult<List<BlogPostItem>>> getAllBlogPosts() {
+		return blogPosts;
+	}
+
+	LiveData<LiveResult<List<BlogPostItem>>> getBlogPosts(GroupId g) {
+		return Transformations.map(blogPosts, result -> {
+			List<BlogPostItem> allPosts = result.getResultOrNull();
+			if (allPosts == null) return result;
+			List<BlogPostItem> groupPosts = new ArrayList<>();
+			for (BlogPostItem item : allPosts) {
+				if (item.getGroupId().equals(g)) groupPosts.add(item);
+			}
+			return new LiveResult<>(groupPosts);
+		});
+	}
+
+	LiveData<LiveResult<BlogPostItem>> getBlogPost(MessageId m) {
+		return Transformations.map(blogPosts, result -> {
+			List<BlogPostItem> allPosts = result.getResultOrNull();
+			if (allPosts == null) {
+				Exception e = requireNonNull(result.getException());
+				return new LiveResult<>(e);
+			}
+			for (BlogPostItem item : allPosts) {
+				if (item.getId().equals(m)) return new LiveResult<>(item);
+			}
+			return new LiveResult<>(new NoSuchMessageException());
+		});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogController.java

@@ -8,6 +8,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 
 import java.util.Collection;
+import java.util.List;
 
 import androidx.annotation.UiThread;
 
@@ -23,7 +24,7 @@ public interface BlogController extends BaseController {
 	void unsetBlogSharingListener(BlogSharingListener listener);
 
 	void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
+			ResultExceptionHandler<List<BlogPostItem>, DbException> handler);
 
 	void loadBlogPost(MessageId m,
 			ResultExceptionHandler<BlogPostItem, DbException> handler);

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogControllerImpl.java

@@ -30,6 +30,7 @@ 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;
 
@@ -140,7 +141,7 @@ class BlogControllerImpl extends BaseControllerImpl
 
 	@Override
 	public void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
+			ResultExceptionHandler<List<BlogPostItem>, DbException> handler) {
 		if (groupId == null) throw new IllegalStateException();
 		loadBlogPosts(groupId, handler);
 	}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -32,6 +32,7 @@ import org.briarproject.briar.android.view.BriarRecyclerView;
 import org.briarproject.briar.api.blog.BlogPostHeader;
 
 import java.util.Collection;
+import java.util.List;
 
 import javax.inject.Inject;
 
@@ -103,8 +104,7 @@ public class BlogFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(requireActivity(), this,
-				getFragmentManager());
+		adapter = new BlogPostAdapter(this, getParentFragmentManager());
 		list = v.findViewById(R.id.postList);
 		layoutManager = new LinearLayoutManager(getActivity());
 		list.setLayoutManager(layoutManager);
@@ -219,7 +219,7 @@ public class BlogFragment extends BaseFragment
 						this) {
 					@Override
 					public void onResultUi(BlogPostItem post) {
-						adapter.add(post);
+//						adapter.add(post);
 						if (local) {
 							list.scrollToPosition(0);
 							displaySnackbar(R.string.blogs_blog_post_created,
@@ -258,14 +258,14 @@ public class BlogFragment extends BaseFragment
 
 	private void loadBlogPosts(boolean reload) {
 		blogController.loadBlogPosts(
-				new UiResultExceptionHandler<Collection<BlogPostItem>,
+				new UiResultExceptionHandler<List<BlogPostItem>,
 						DbException>(this) {
 					@Override
-					public void onResultUi(Collection<BlogPostItem> posts) {
+					public void onResultUi(List<BlogPostItem> posts) {
 						if (posts.isEmpty()) {
 							list.showData();
 						} else {
-							adapter.addAll(posts);
+							adapter.submitList(posts);
 							if (reload || layoutManagerState == null) {
 								list.scrollToPosition(0);
 							} else {

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogModule.java

@@ -4,13 +4,25 @@ import org.briarproject.briar.android.activity.ActivityScope;
 import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.controller.SharingController;
 import org.briarproject.briar.android.controller.SharingControllerImpl;
+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 BlogModule {
 
+	@Module
+	public abstract static class BindsModule {
+		@Binds
+		@IntoMap
+		@ViewModelKey(FeedViewModel.class)
+		abstract ViewModel bindFeedViewModel(FeedViewModel feedViewModel);
+	}
+
 	@ActivityScope
 	@Provides
 	BlogController provideBlogController(BaseActivity activity,
@@ -19,12 +31,6 @@ public class BlogModule {
 		return blogController;
 	}
 
-	@ActivityScope
-	@Provides
-	FeedController provideFeedController(FeedControllerImpl feedController) {
-		return feedController;
-	}
-
 	@ActivityScope
 	@Provides
 	SharingController provideSharingController(

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostAdapter.java

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.blog;
 
-import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -8,22 +7,33 @@ import android.view.ViewGroup;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.BriarAdapter;
 
 import androidx.annotation.Nullable;
 import androidx.fragment.app.FragmentManager;
+import androidx.recyclerview.widget.DiffUtil;
+import androidx.recyclerview.widget.ListAdapter;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
+class BlogPostAdapter extends ListAdapter<BlogPostItem, BlogPostViewHolder> {
 
 	private final OnBlogPostClickListener listener;
 	@Nullable
 	private final FragmentManager fragmentManager;
 
-	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener,
+	BlogPostAdapter(OnBlogPostClickListener listener,
 			@Nullable FragmentManager fragmentManager) {
-		super(ctx, BlogPostItem.class);
+		super(new DiffUtil.ItemCallback<BlogPostItem>() {
+			@Override
+			public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
+				return a.getId().equals(b.getId());
+			}
+
+			@Override
+			public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
+				return a.isRead() == b.isRead();
+			}
+		});
 		this.listener = listener;
 		this.fragmentManager = fragmentManager;
 	}
@@ -31,29 +41,14 @@ class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
 	@Override
 	public BlogPostViewHolder onCreateViewHolder(ViewGroup parent,
 			int viewType) {
-		View v = LayoutInflater.from(ctx).inflate(
+		View v = LayoutInflater.from(parent.getContext()).inflate(
 				R.layout.list_item_blog_post, parent, false);
 		return new BlogPostViewHolder(v, false, listener, fragmentManager);
 	}
 
 	@Override
 	public void onBindViewHolder(BlogPostViewHolder ui, int position) {
-		ui.bindItem(getItemAt(position));
-	}
-
-	@Override
-	public int compare(BlogPostItem a, BlogPostItem b) {
-		return a.compareTo(b);
-	}
-
-	@Override
-	public boolean areContentsTheSame(BlogPostItem a, BlogPostItem b) {
-		return a.isRead() == b.isRead();
-	}
-
-	@Override
-	public boolean areItemsTheSame(BlogPostItem a, BlogPostItem b) {
-		return a.getId().equals(b.getId());
+		ui.bindItem(getItem(position));
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostItem.java

@@ -74,9 +74,6 @@ public class BlogPostItem implements Comparable<BlogPostItem> {
 
 	protected static int compare(BlogPostHeader h1, BlogPostHeader h2) {
 		// The newest post comes first
-		long aTime = h1.getTimeReceived(), bTime = h2.getTimeReceived();
-		if (aTime > bTime) return -1;
-		if (aTime < bTime) return 1;
-		return 0;
+		return Long.compare(h2.getTimeReceived(), h1.getTimeReceived());
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedController.java

@@ -1,32 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.blog.Blog;
-
-import java.util.Collection;
-
-import androidx.annotation.UiThread;
-
-@NotNullByDefault
-public interface FeedController extends BaseController {
-
-	void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);
-
-	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
-
-	@UiThread
-	void setFeedListener(FeedListener listener);
-
-	@UiThread
-	void unsetFeedListener(FeedListener listener);
-
-	@NotNullByDefault
-	interface FeedListener extends BlogListener {
-
-		@UiThread
-		void onBlogAdded();
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedControllerImpl.java

@@ -1,143 +0,0 @@
-package org.briarproject.briar.android.blog;
-
-import org.briarproject.bramble.api.db.DatabaseExecutor;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.NoSuchGroupException;
-import org.briarproject.bramble.api.db.NoSuchMessageException;
-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.lifecycle.LifecycleManager;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
-import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogManager;
-import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.inject.Inject;
-
-import androidx.annotation.Nullable;
-
-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;
-import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-class FeedControllerImpl extends BaseControllerImpl implements FeedController {
-
-	private static final Logger LOG =
-			Logger.getLogger(FeedControllerImpl.class.getName());
-
-	// UI thread
-	@Nullable
-	private FeedListener listener;
-
-	@Inject
-	FeedControllerImpl(@DatabaseExecutor Executor dbExecutor,
-			LifecycleManager lifecycleManager, EventBus eventBus,
-			AndroidNotificationManager notificationManager,
-			IdentityManager identityManager, BlogManager blogManager) {
-		super(dbExecutor, lifecycleManager, eventBus, notificationManager,
-				identityManager, blogManager);
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		if (listener == null) throw new IllegalStateException();
-		notificationManager.blockAllBlogPostNotifications();
-		notificationManager.clearAllBlogPostNotifications();
-	}
-
-	@Override
-	public void onStop() {
-		super.onStop();
-		notificationManager.unblockAllBlogPostNotifications();
-	}
-
-	@Override
-	public void setFeedListener(FeedListener listener) {
-		this.listener = listener;
-	}
-
-	@Override
-	public void unsetFeedListener(FeedListener listener) {
-		if (this.listener == listener) this.listener = null;
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (listener == null) throw new IllegalStateException();
-		if (e instanceof BlogPostAddedEvent) {
-			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
-			LOG.info("Blog post added");
-			listener.onBlogPostAdded(b.getHeader(), b.isLocal());
-		} else if (e instanceof GroupAddedEvent) {
-			GroupAddedEvent g = (GroupAddedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog added");
-				listener.onBlogAdded();
-			}
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Blog removed");
-				listener.onBlogRemoved();
-			}
-		}
-	}
-
-	@Override
-	public void loadBlogPosts(
-			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Collection<BlogPostItem> posts = new ArrayList<>();
-				for (Blog b : blogManager.getBlogs()) {
-					try {
-						posts.addAll(loadItems(b.getId()));
-					} catch (NoSuchGroupException | NoSuchMessageException e) {
-						logException(LOG, WARNING, e);
-					}
-				}
-				logDuration(LOG, "Loading all posts", start);
-				handler.onResult(posts);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-	@Override
-	public void loadPersonalBlog(
-			ResultExceptionHandler<Blog, DbException> handler) {
-		runOnDbThread(() -> {
-			try {
-				long start = now();
-				Author a = identityManager.getLocalAuthor();
-				Blog b = blogManager.getPersonalBlog(a);
-				logDuration(LOG, "Loading personal blog", start);
-				handler.onResult(b);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-				handler.onException(e);
-			}
-		});
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -10,52 +10,44 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 
-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.blog.FeedController.FeedListener;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 import org.briarproject.briar.api.blog.Blog;
-import org.briarproject.briar.api.blog.BlogPostHeader;
 
-import java.util.Collection;
-import java.util.logging.Logger;
+import java.util.List;
 
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
-import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
 @UiThread
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class FeedFragment extends BaseFragment implements
-		OnBlogPostClickListener, FeedListener {
+public class FeedFragment extends BaseFragment
+		implements OnBlogPostClickListener {
 
 	public final static String TAG = FeedFragment.class.getName();
-	private static final Logger LOG = Logger.getLogger(TAG);
 
 	@Inject
-	FeedController feedController;
+	ViewModelProvider.Factory viewModelFactory;
 
+	private FeedViewModel viewModel;
 	private BlogPostAdapter adapter;
 	private LinearLayoutManager layoutManager;
 	private BriarRecyclerView list;
 	@Nullable
-	private Blog personalBlog;
-	@Nullable
 	private Parcelable layoutManagerState;
 
 	public static FeedFragment newInstance() {
@@ -70,7 +62,12 @@ public class FeedFragment extends BaseFragment implements
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
-		feedController.setFeedListener(this);
+		// TODO don't use NavDrawerActivity scope here
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(FeedViewModel.class);
+		// TODO ideally we only do this once when the ViewModel gets created
+		viewModel.loadPersonalBlog();
+		viewModel.loadAllBlogPosts();
 	}
 
 	@Nullable
@@ -82,8 +79,7 @@ public class FeedFragment extends BaseFragment implements
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter =
-				new BlogPostAdapter(getActivity(), this, getFragmentManager());
+		adapter = new BlogPostAdapter(this, getParentFragmentManager());
 
 		layoutManager = new LinearLayoutManager(getActivity());
 		list = v.findViewById(R.id.postList);
@@ -93,6 +89,12 @@ public class FeedFragment extends BaseFragment implements
 		list.setEmptyText(R.string.blogs_feed_empty_state);
 		list.setEmptyAction(R.string.blogs_feed_empty_state_action);
 
+		viewModel.getAllBlogPosts().observe(getViewLifecycleOwner(), result ->
+				result
+						.onError(this::handleException)
+						.onSuccess(this::onBlogPostsLoaded)
+		);
+
 		if (savedInstanceState != null) {
 			layoutManagerState =
 					savedInstanceState.getParcelable("layoutManager");
@@ -101,40 +103,19 @@ public class FeedFragment extends BaseFragment implements
 		return v;
 	}
 
-	@Override
-	public void onActivityResult(int requestCode, int resultCode,
-			@Nullable Intent data) {
-		super.onActivityResult(requestCode, resultCode, data);
-
-		// The BlogPostAddedEvent arrives when the controller is not listening
-		if (requestCode == REQUEST_WRITE_BLOG_POST && resultCode == RESULT_OK) {
-			showSnackBar(R.string.blogs_blog_post_created);
-		}
-	}
-
 	@Override
 	public void onStart() {
 		super.onStart();
-		feedController.onStart();
+		viewModel.blockAllBlogPostNotifications();
+		viewModel.clearAllBlogPostNotifications();
 		list.startPeriodicUpdate();
-		loadPersonalBlog();
-		loadBlogPosts(false);
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		feedController.onStop();
-		adapter.clear();
-		list.showProgressBar();
+		viewModel.unblockAllBlogPostNotifications();
 		list.stopPeriodicUpdate();
-		// TODO save list position in database/preferences?
-	}
-
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		feedController.unsetFeedListener(this);
 	}
 
 	@Override
@@ -146,50 +127,16 @@ public class FeedFragment extends BaseFragment implements
 		}
 	}
 
-	private void loadPersonalBlog() {
-		feedController.loadPersonalBlog(
-				new UiResultExceptionHandler<Blog, DbException>(this) {
-					@Override
-					public void onResultUi(Blog b) {
-						personalBlog = b;
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
-	private void loadBlogPosts(boolean clear) {
-		int revision = adapter.getRevision();
-		feedController.loadBlogPosts(
-				new UiResultExceptionHandler<Collection<BlogPostItem>, DbException>(
-						this) {
-					@Override
-					public void onResultUi(Collection<BlogPostItem> posts) {
-						if (revision == adapter.getRevision()) {
-							adapter.incrementRevision();
-							if (clear) adapter.setItems(posts);
-							else adapter.addAll(posts);
-							if (posts.isEmpty()) list.showData();
-							if (layoutManagerState == null) {
-								list.scrollToPosition(0);  // Scroll to the top
-							} else {
-								layoutManager.onRestoreInstanceState(
-										layoutManagerState);
-							}
-						} else {
-							LOG.info("Concurrent update, reloading");
-							loadBlogPosts(clear);
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+	private void onBlogPostsLoaded(List<BlogPostItem> items) {
+		if (items.isEmpty()) list.showData();
+		else adapter.submitList(items, () -> {
+			Boolean wasLocal = viewModel.getPostAddedWasLocalAndReset();
+			if (wasLocal != null && wasLocal) {
+				showSnackBar(R.string.blogs_blog_post_created);
+			} else if (wasLocal != null) {
+				showSnackBar(R.string.blogs_blog_post_received);
+			}
+		});
 	}
 
 	@Override
@@ -200,52 +147,27 @@ public class FeedFragment extends BaseFragment implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		if (personalBlog == null) return false;
-		switch (item.getItemId()) {
-			case R.id.action_write_blog_post:
-				Intent i1 =
-						new Intent(getActivity(), WriteBlogPostActivity.class);
-				i1.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-				startActivityForResult(i1, REQUEST_WRITE_BLOG_POST);
-				return true;
-			case R.id.action_rss_feeds_import:
-				Intent i2 =
-						new Intent(getActivity(), RssFeedImportActivity.class);
-				startActivity(i2);
-				return true;
-			case R.id.action_rss_feeds_manage:
-				Intent i3 =
-						new Intent(getActivity(), RssFeedManageActivity.class);
-				i3.putExtra(GROUP_ID, personalBlog.getId().getBytes());
-				startActivity(i3);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		int itemId = item.getItemId();
+		if (itemId == R.id.action_write_blog_post) {
+			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			if (personalBlog == null) return false;
+			Intent i = new Intent(getActivity(), WriteBlogPostActivity.class);
+			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_rss_feeds_import) {
+			Intent i = new Intent(getActivity(), RssFeedImportActivity.class);
+			startActivity(i);
+			return true;
+		} else if (itemId == R.id.action_rss_feeds_manage) {
+			Blog personalBlog = viewModel.getPersonalBlog().getValue();
+			if (personalBlog == null) return false;
+			Intent i = new Intent(getActivity(), RssFeedManageActivity.class);
+			i.putExtra(GROUP_ID, personalBlog.getId().getBytes());
+			startActivity(i);
+			return true;
 		}
-	}
-
-	@Override
-	public void onBlogPostAdded(BlogPostHeader header, boolean local) {
-		feedController.loadBlogPost(header,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						adapter.incrementRevision();
-						adapter.add(post);
-						if (local) {
-							showSnackBar(R.string.blogs_blog_post_created);
-						} else {
-							showSnackBar(R.string.blogs_blog_post_received);
-						}
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				}
-		);
+		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
@@ -257,10 +179,10 @@ public class FeedFragment extends BaseFragment implements
 
 	@Override
 	public void onAuthorClick(BlogPostItem post) {
-		Intent i = new Intent(getContext(), BlogActivity.class);
+		Intent i = new Intent(requireContext(), BlogActivity.class);
 		i.putExtra(GROUP_ID, post.getGroupId().getBytes());
 		i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
-		getContext().startActivity(i);
+		requireContext().startActivity(i);
 	}
 
 	@Override
@@ -283,14 +205,4 @@ public class FeedFragment extends BaseFragment implements
 		sb.make(list, stringRes, LENGTH_LONG).show();
 	}
 
-	@Override
-	public void onBlogAdded() {
-		loadBlogPosts(false);
-	}
-
-	@Override
-	public void onBlogRemoved() {
-		loadBlogPosts(true);
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -5,19 +5,19 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
-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.android.activity.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 
+import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @UiThread
@@ -27,18 +27,16 @@ public class FeedPostFragment extends BasePostFragment {
 
 	private static final String TAG = FeedPostFragment.class.getName();
 
-	private GroupId blogId;
-
 	@Inject
-	FeedController feedController;
+	ViewModelProvider.Factory viewModelFactory;
+
+	private FeedViewModel viewModel;
 
 	static FeedPostFragment newInstance(GroupId blogId, MessageId postId) {
 		FeedPostFragment f = new FeedPostFragment();
-
 		Bundle bundle = new Bundle();
 		bundle.putByteArray(GROUP_ID, blogId.getBytes());
 		bundle.putByteArray(POST_ID, postId.getBytes());
-
 		f.setArguments(bundle);
 		return f;
 	}
@@ -46,6 +44,8 @@ public class FeedPostFragment extends BasePostFragment {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(FeedViewModel.class);
 	}
 
 	@Nullable
@@ -54,10 +54,14 @@ public class FeedPostFragment extends BasePostFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		Bundle args = requireArguments();
-		byte[] b = args.getByteArray(GROUP_ID);
-		if (b == null) throw new IllegalStateException("No group ID in args");
-		blogId = new GroupId(b);
-
+		GroupId groupId =
+				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
+		MessageId postId =
+				new MessageId(requireNonNull(args.getByteArray(POST_ID)));
+		viewModel.loadBlogPost(groupId, postId).observe(getViewLifecycleOwner(),
+				result -> result.onError(this::handleException)
+						.onSuccess(this::onBlogPostLoaded)
+		);
 		return super.onCreateView(inflater, container, savedInstanceState);
 	}
 
@@ -66,22 +70,4 @@ public class FeedPostFragment extends BasePostFragment {
 		return TAG;
 	}
 
-	@Override
-	public void onStart() {
-		super.onStart();
-		feedController.loadBlogPost(blogId, postId,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem post) {
-						onBlogPostLoaded(post);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
-	}
-
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedViewModel.java

@@ -0,0 +1,174 @@
+package org.briarproject.briar.android.blog;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
+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.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.blog.Blog;
+import org.briarproject.briar.api.blog.BlogManager;
+import org.briarproject.briar.api.blog.BlogPostHeader;
+import org.briarproject.briar.api.blog.event.BlogPostAddedEvent;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+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;
+import static org.briarproject.briar.api.blog.BlogManager.CLIENT_ID;
+
+@NotNullByDefault
+class FeedViewModel extends BaseViewModel {
+
+	private static final Logger LOG = getLogger(FeedViewModel.class.getName());
+
+	protected final AndroidNotificationManager notificationManager;
+
+	private final MutableLiveData<Blog> personalBlog = new MutableLiveData<>();
+	@Nullable
+	private Boolean postAddedWasLocal = null;
+
+	@Inject
+	FeedViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
+			IdentityManager identityManager,
+			BlogManager blogManager,
+			AndroidNotificationManager notificationManager) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor,
+				eventBus, identityManager, blogManager);
+		this.notificationManager = notificationManager;
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof BlogPostAddedEvent) {
+			BlogPostAddedEvent b = (BlogPostAddedEvent) e;
+			LOG.info("Blog post added");
+			onBlogPostAdded(b.getHeader(), b.isLocal());
+		} else if (e instanceof GroupAddedEvent) {
+			GroupAddedEvent g = (GroupAddedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog added");
+				loadAllBlogPosts();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Blog removed");
+				loadAllBlogPosts();
+			}
+		}
+	}
+
+	void blockAllBlogPostNotifications() {
+		notificationManager.blockAllBlogPostNotifications();
+	}
+
+	void clearAllBlogPostNotifications() {
+		notificationManager.clearAllBlogPostNotifications();
+	}
+
+	void unblockAllBlogPostNotifications() {
+		notificationManager.unblockAllBlogPostNotifications();
+	}
+
+	void loadPersonalBlog() {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				Author a = identityManager.getLocalAuthor();
+				Blog b = blogManager.getPersonalBlog(a);
+				logDuration(LOG, "Loading personal blog", start);
+				personalBlog.postValue(b);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<Blog> getPersonalBlog() {
+		return personalBlog;
+	}
+
+	void loadAllBlogPosts() {
+		loadList(this::loadAllBlogPosts, blogPosts::setValue);
+	}
+
+	@DatabaseExecutor
+	private List<BlogPostItem> loadAllBlogPosts(Transaction txn)
+			throws DbException {
+		long start = now();
+		List<BlogPostItem> posts = new ArrayList<>();
+		for (GroupId g : blogManager.getBlogIds(txn)) {
+			try {
+				posts.addAll(loadBlogPosts(txn, g));
+			} catch (NoSuchMessageException e) {
+				logException(LOG, WARNING, e);
+			}
+		}
+		Collections.sort(posts);
+		logDuration(LOG, "Loading all posts", start);
+		return posts;
+	}
+
+	private void onBlogPostAdded(BlogPostHeader header, boolean local) {
+		postAddedWasLocal = local;
+		runOnDbThread(() -> {
+			try {
+				db.transaction(true, txn -> {
+					BlogPostItem item = getItem(txn, header);
+					txn.attach(() -> {
+						List<BlogPostItem> items = addListItem(blogPosts, item);
+						if (items != null) {
+							Collections.sort(items);
+							blogPosts.setValue(new LiveResult<>(items));
+						}
+					});
+				});
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@UiThread
+	@Nullable
+	Boolean getPostAddedWasLocalAndReset() {
+		if (postAddedWasLocal == null) return null;
+		boolean wasLocal = postAddedWasLocal;
+		postAddedWasLocal = null;
+		return wasLocal;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -7,15 +7,12 @@ import android.view.ViewGroup;
 import android.widget.ProgressBar;
 import android.widget.ScrollView;
 
-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.ActivityComponent;
-import org.briarproject.briar.android.controller.handler.UiExceptionHandler;
-import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
@@ -27,6 +24,8 @@ import java.util.List;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import androidx.lifecycle.ViewModelProvider;
+
 import static android.view.View.FOCUS_DOWN;
 import static android.view.View.GONE;
 import static android.view.View.INVISIBLE;
@@ -42,12 +41,13 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 
 	public static final String TAG = ReblogFragment.class.getName();
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private FeedViewModel viewModel;
 	private ViewHolder ui;
 	private BlogPostItem item;
 
-	@Inject
-	FeedController feedController;
-
 	static ReblogFragment newInstance(GroupId groupId, MessageId messageId) {
 		ReblogFragment f = new ReblogFragment();
 
@@ -67,6 +67,8 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(FeedViewModel.class);
 	}
 
 	@Override
@@ -90,30 +92,20 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 		ui.input.setMaxTextLength(MAX_BLOG_POST_TEXT_LENGTH);
 		showProgressBar();
 
-		feedController.loadBlogPost(blogId, postId,
-				new UiResultExceptionHandler<BlogPostItem, DbException>(
-						this) {
-					@Override
-					public void onResultUi(BlogPostItem result) {
-						item = result;
-						bindViewHolder();
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.loadBlogPost(blogId, postId).observe(getViewLifecycleOwner(),
+				result -> result.onError(this::handleException)
+						.onSuccess(this::bindViewHolder)
+		);
 
 		return v;
 	}
 
-	private void bindViewHolder() {
-		if (item == null) return;
+	private void bindViewHolder(BlogPostItem item) {
+		this.item = item;
 
 		hideProgressBar();
 
-		ui.post.bindItem(item);
+		ui.post.bindItem(this.item);
 		ui.post.hideReblogButton();
 
 		ui.input.setReady(true);
@@ -124,13 +116,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	public void onSendClick(@Nullable String text,
 			List<AttachmentHeader> headers) {
 		ui.input.hideSoftKeyboard();
-		feedController.repeatPost(item, text,
-				new UiExceptionHandler<DbException>(this) {
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleException(exception);
-					}
-				});
+		viewModel.repeatPost(item, text);
 		finish();
 	}
 
@@ -165,7 +151,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 				public void onAuthorClick(BlogPostItem post) {
 					// probably don't want to allow author clicks here
 				}
-			}, getFragmentManager());
+			}, getParentFragmentManager());
 			input = v.findViewById(R.id.inputText);
 		}
 	}

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

@@ -142,6 +142,24 @@ public abstract class DbViewModel extends AndroidViewModel {
 		void accept(T t);
 	}
 
+	/**
+	 * Creates a copy of the list available in the given LiveData
+	 * and adds the given item to the copy.
+	 *
+	 * @return a copy of the list in the LiveData with item added or null when
+	 * <ul>
+	 * <li> LiveData does not have a value
+	 * <li> LiveResult in the LiveData has an error
+	 * </ul>
+	 */
+	@Nullable
+	protected <T> List<T> addListItem(LiveData<LiveResult<List<T>>> liveData, T item) {
+		List<T> items = getListCopy(liveData);
+		if (items == null) return null;
+		items.add(item);
+		return items;
+	}
+
 	/**
 	 * Creates a copy of the list available in the given LiveData
 	 * and replaces items where the given test function returns true.