[android] allow to select multiple conversation messages

briar-android/build.gradle

@@ -97,6 +97,7 @@ dependencies {
 	implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
 	implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
 	implementation 'com.google.android.material:material:1.1.0-beta01'
+	implementation 'androidx.recyclerview:recyclerview-selection:1.0.0'
 
 	implementation 'ch.acra:acra:4.11'
 	implementation 'info.guardianproject.panic:panic:1.0'

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -7,7 +7,9 @@ import android.os.Bundle;
 import android.os.Parcelable;
 import android.transition.Slide;
 import android.transition.Transition;
+import android.util.Log;
 import android.util.SparseArray;
+import android.view.ActionMode;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
@@ -98,13 +100,20 @@ import androidx.core.content.ContextCompat;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
+import androidx.recyclerview.selection.Selection;
+import androidx.recyclerview.selection.SelectionPredicates;
+import androidx.recyclerview.selection.SelectionTracker;
+import androidx.recyclerview.selection.SelectionTracker.SelectionObserver;
+import androidx.recyclerview.selection.StorageStrategy;
 import androidx.recyclerview.widget.LinearLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
 import de.hdodenhof.circleimageview.CircleImageView;
 import im.delight.android.identicons.IdenticonDrawable;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt;
 
 import static android.os.Build.VERSION.SDK_INT;
 import static android.view.Gravity.RIGHT;
+import static android.widget.Toast.LENGTH_LONG;
 import static android.widget.Toast.LENGTH_SHORT;
 import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static androidx.core.view.ViewCompat.setTransitionName;
@@ -120,6 +129,7 @@ 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.bramble.util.StringUtils.fromHexString;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_ATTACH_IMAGE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRODUCTION;
@@ -137,7 +147,7 @@ import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_PRIVAT
 @ParametersNotNullByDefault
 public class ConversationActivity extends BriarActivity
 		implements EventListener, ConversationListener, TextCache,
-		AttachmentCache, AttachmentListener {
+		AttachmentCache, AttachmentListener, ActionMode.Callback {
 
 	public static final String CONTACT_ID = "briar.CONTACT_ID";
 
@@ -194,8 +204,11 @@ public class ConversationActivity extends BriarActivity
 	private LinearLayoutManager layoutManager;
 	private TextInputView textInputView;
 	private TextSendController sendController;
+	private SelectionTracker<String> tracker;
 	@Nullable
 	private Parcelable layoutManagerState;
+	@Nullable
+	private ActionMode actionMode;
 
 	private volatile ContactId contactId;
 
@@ -257,6 +270,9 @@ public class ConversationActivity extends BriarActivity
 		ConversationScrollListener scrollListener =
 				new ConversationScrollListener(adapter, viewModel);
 		list.getRecyclerView().addOnScrollListener(scrollListener);
+		if (featureFlags.shouldEnablePrivateMessageDeletion()) {
+			addSelectionTracker();
+		}
 
 		textInputView = findViewById(R.id.text_input_container);
 		if (featureFlags.shouldEnableImageAttachments()) {
@@ -346,12 +362,14 @@ public class ConversationActivity extends BriarActivity
 			layoutManagerState = layoutManager.onSaveInstanceState();
 			outState.putParcelable("layoutManager", layoutManagerState);
 		}
+		if (tracker != null) tracker.onSaveInstanceState(outState);
 	}
 
 	@Override
 	protected void onRestoreInstanceState(Bundle savedInstanceState) {
 		super.onRestoreInstanceState(savedInstanceState);
 		layoutManagerState = savedInstanceState.getParcelable("layoutManager");
+		if (tracker != null) tracker.onRestoreInstanceState(savedInstanceState);
 	}
 
 	@Override
@@ -409,6 +427,84 @@ public class ConversationActivity extends BriarActivity
 		}
 	}
 
+	@Override
+	public boolean onCreateActionMode(ActionMode mode, Menu menu) {
+		MenuInflater inflater = mode.getMenuInflater();
+		inflater.inflate(R.menu.conversation_message_actions, menu);
+		return true;
+	}
+
+	@Override
+	public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
+		return false; // no update needed
+	}
+
+	@Override
+	public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
+		if (item.getItemId() == R.id.action_delete) {
+			Log.e("TEST", "selected: " + getSelection());
+			Toast.makeText(this, "Not yet implemented", LENGTH_LONG).show();
+			return true;
+		}
+		return false;
+	}
+
+	@Override
+	public void onDestroyActionMode(ActionMode mode) {
+		tracker.clearSelection();
+		actionMode = null;
+	}
+
+	private void addSelectionTracker() {
+		RecyclerView recyclerView = list.getRecyclerView();
+		if (recyclerView.getAdapter() != adapter)
+			throw new IllegalStateException();
+
+		tracker = new SelectionTracker.Builder<>(
+				"conversationSelection",
+				recyclerView,
+				new ConversationItemKeyProvider(adapter),
+				new ConversationItemDetailsLookup(recyclerView),
+				StorageStrategy.createStringStorage()
+		).withSelectionPredicate(
+				SelectionPredicates.createSelectAnything()
+		).build();
+
+		SelectionObserver<String> observer = new SelectionObserver<String>() {
+			@Override
+			public void onItemStateChanged(String key, boolean selected) {
+				if (selected && actionMode == null) {
+					actionMode = startActionMode(ConversationActivity.this);
+					updateActionModeTitle();
+				} else if (actionMode != null) {
+					if (selected || tracker.hasSelection()) {
+						updateActionModeTitle();
+					} else {
+						actionMode.finish();
+					}
+				}
+			}
+		};
+		tracker.addObserver(observer);
+		adapter.setSelectionTracker(tracker);
+	}
+
+	private void updateActionModeTitle() {
+		if (actionMode == null) throw new IllegalStateException();
+		String title = String.valueOf(tracker.getSelection().size());
+		actionMode.setTitle(title);
+	}
+
+	private Collection<MessageId> getSelection() {
+		Selection<String> selection = tracker.getSelection();
+		List<MessageId> messages = new ArrayList<>(selection.size());
+		for (String str : selection) {
+			MessageId id = new MessageId(fromHexString(str));
+			messages.add(id);
+		}
+		return messages;
+	}
+
 	@UiThread
 	private void displayContactOnlineStatus() {
 		if (connectionRegistry.isConnected(contactId)) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationAdapter.java

@@ -13,12 +13,14 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.BriarAdapter;
 import org.briarproject.briar.android.util.ItemReturningAdapter;
 
-import javax.annotation.Nullable;
-
 import androidx.annotation.LayoutRes;
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.SelectionTracker;
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView.RecycledViewPool;
 
+import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
+
 @NotNullByDefault
 class ConversationAdapter
 		extends BriarAdapter<ConversationItem, ConversationItemViewHolder>
@@ -27,6 +29,8 @@ class ConversationAdapter
 	private ConversationListener listener;
 	private final RecycledViewPool imageViewPool;
 	private final ImageItemDecoration imageItemDecoration;
+	@Nullable
+	private SelectionTracker<String> tracker = null;
 
 	ConversationAdapter(Context ctx,
 			ConversationListener conversationListener) {
@@ -45,6 +49,17 @@ class ConversationAdapter
 		return item.getLayout();
 	}
 
+	String getItemKey(int position) {
+		return items.get(position).getKey();
+	}
+
+	int getPositionOfKey(String key) {
+		for (int i = 0; i < items.size(); i++) {
+			if (key.equals(items.get(i).getKey())) return i;
+		}
+		return NO_POSITION;
+	}
+
 	@Override
 	public ConversationItemViewHolder onCreateViewHolder(ViewGroup viewGroup,
 			@LayoutRes int type) {
@@ -71,7 +86,8 @@ class ConversationAdapter
 	@Override
 	public void onBindViewHolder(ConversationItemViewHolder ui, int position) {
 		ConversationItem item = items.get(position);
-		ui.bind(item);
+		boolean selected = tracker != null && tracker.isSelected(item.getKey());
+		ui.bind(item, selected);
 	}
 
 	@Override
@@ -91,6 +107,10 @@ class ConversationAdapter
 		return c1.equals(c2);
 	}
 
+	void setSelectionTracker(SelectionTracker<String> tracker) {
+		this.tracker = tracker;
+	}
+
 	@Nullable
 	ConversationItem getLastItem() {
 		if (items.size() > 0) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItem.java

@@ -10,6 +10,8 @@ import javax.annotation.concurrent.NotThreadSafe;
 
 import androidx.annotation.LayoutRes;
 
+import static org.briarproject.bramble.util.StringUtils.toHexString;
+
 @NotThreadSafe
 @NotNullByDefault
 abstract class ConversationItem {
@@ -45,6 +47,10 @@ abstract class ConversationItem {
 		return id;
 	}
 
+	String getKey() {
+		return toHexString(id.getBytes());
+	}
+
 	GroupId getGroupId() {
 		return groupId;
 	}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItemDetailsLookup.java

@@ -0,0 +1,53 @@
+package org.briarproject.briar.android.conversation;
+
+import android.view.MotionEvent;
+import android.view.View;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemDetailsLookup;
+import androidx.recyclerview.widget.RecyclerView;
+
+import static androidx.recyclerview.widget.RecyclerView.NO_POSITION;
+
+@NotNullByDefault
+class ConversationItemDetailsLookup extends ItemDetailsLookup<String > {
+
+	private final RecyclerView recyclerView;
+
+	ConversationItemDetailsLookup(RecyclerView recyclerView) {
+		this.recyclerView = recyclerView;
+	}
+
+	@Nullable
+	@Override
+	public ItemDetails<String> getItemDetails(MotionEvent e) {
+		// find view that corresponds to MotionEvent
+		View view = recyclerView.findChildViewUnder(e.getX(), e.getY());
+		if (view == null) return null;
+
+		// get position
+		int pos = recyclerView.getChildAdapterPosition(view);
+		if (pos == NO_POSITION) return null;
+
+		// get key ID
+		ConversationItemViewHolder holder =
+				(ConversationItemViewHolder) recyclerView.getChildViewHolder(view);
+		String id = holder.getItemKey();
+		if (id == null) return null;
+
+		return new ItemDetails<String>() {
+			@Override
+			public int getPosition() {
+				return pos;
+			}
+
+			@Override
+			public String getSelectionKey() {
+				return id;
+			}
+		};
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItemKeyProvider.java

@@ -0,0 +1,29 @@
+package org.briarproject.briar.android.conversation;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import androidx.annotation.Nullable;
+import androidx.recyclerview.selection.ItemKeyProvider;
+
+@NotNullByDefault
+class ConversationItemKeyProvider extends ItemKeyProvider<String> {
+
+	private final ConversationAdapter adapter;
+
+	protected ConversationItemKeyProvider(ConversationAdapter adapter) {
+		super(SCOPE_MAPPED);
+		this.adapter = adapter;
+	}
+
+	@Nullable
+	@Override
+	public String getKey(int position) {
+		return adapter.getItemKey(position);
+	}
+
+	@Override
+	public int getPosition(String key) {
+		return adapter.getPositionOfKey(key);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationItemViewHolder.java

@@ -25,6 +25,8 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 	private final OutItemViewHolder outViewHolder;
 	private final TextView text;
 	protected final TextView time;
+	@Nullable
+	private String itemKey = null;
 
 	ConversationItemViewHolder(View v, ConversationListener listener,
 			boolean isIncoming) {
@@ -37,7 +39,9 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 	}
 
 	@CallSuper
-	void bind(ConversationItem item) {
+	void bind(ConversationItem item, boolean selected) {
+		itemKey = item.getKey();
+
 		if (item.getText() != null) {
 			text.setText(trim(item.getText()));
 		}
@@ -52,4 +56,9 @@ abstract class ConversationItemViewHolder extends ViewHolder {
 		return outViewHolder == null;
 	}
 
+	@Nullable
+	String getItemKey() {
+		return itemKey;
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationMessageViewHolder.java

@@ -61,8 +61,8 @@ class ConversationMessageViewHolder extends ConversationItemViewHolder {
 	}
 
 	@Override
-	void bind(ConversationItem conversationItem) {
+	void bind(ConversationItem conversationItem, boolean selected) {
-		super.bind(conversationItem);
+		super.bind(conversationItem, selected);
 		ConversationMessageItem item =
 				(ConversationMessageItem) conversationItem;
 		if (item.getAttachments().isEmpty()) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationNoticeViewHolder.java

@@ -28,9 +28,9 @@ class ConversationNoticeViewHolder extends ConversationItemViewHolder {
 
 	@Override
 	@CallSuper
-	void bind(ConversationItem item) {
+	void bind(ConversationItem item, boolean selected) {
 		ConversationNoticeItem notice = (ConversationNoticeItem) item;
-		super.bind(notice);
+		super.bind(notice, selected);
 
 		String text = notice.getMsgText();
 		if (isNullOrEmpty(text)) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationRequestViewHolder.java

@@ -26,9 +26,9 @@ class ConversationRequestViewHolder extends ConversationNoticeViewHolder {
 	}
 
 	@Override
-	void bind(ConversationItem item) {
+	void bind(ConversationItem item, boolean selected) {
 		ConversationRequestItem request = (ConversationRequestItem) item;
-		super.bind(request);
+		super.bind(request, selected);
 
 		if (request.wasAnswered() && request.canBeOpened()) {
 			acceptButton.setVisibility(VISIBLE);

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

@@ -0,0 +1,12 @@
+<?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">
+
+	<item
+		android:id="@+id/action_delete"
+		android:icon="@drawable/action_delete_white"
+		android:title="@string/delete"
+		app:showAsAction="always"/>
+
+</menu>

briar-android/src/main/res/values/themes.xml

@@ -8,6 +8,7 @@
 		<item name="android:textColorLink">@color/briar_text_link</item>
 		<item name="android:windowBackground">@color/window_background</item>
 		<item name="android:windowAnimationStyle">@style/ActivityAnimation</item>
+		<item name="windowActionModeOverlay">true</item>
 		<item name="alertDialogTheme">@style/BriarDialogTheme.Neutral</item>
 		<item name="preferenceTheme">@style/PreferenceThemeOverlay.v14.Material</item>
 	</style>

briar-android/witness.gradle

@@ -36,6 +36,7 @@ dependencyVerification {
         'androidx.localbroadcastmanager:localbroadcastmanager:1.0.0:localbroadcastmanager-1.0.0.aar:e71c328ceef5c4a7d76f2d86df1b65d65fe2acf868b1a4efd84a3f34336186d8',
         'androidx.preference:preference:1.1.0:preference-1.1.0.aar:6cf1a099b03b3254041b04701841865b2708c0b546b9036c8b0dada0aa59de57',
         'androidx.print:print:1.0.0:print-1.0.0.aar:1d5c7f3135a1bba661fc373fd72e11eb0a4adbb3396787826dd8e4190d5d9edd',
+        'androidx.recyclerview:recyclerview-selection:1.0.0:recyclerview-selection-1.0.0.aar:db3db72af8cfcd701ab6ed7a080327a2e993e3a429f5efb8f0c108bff38c4922',
         'androidx.recyclerview:recyclerview:1.1.0-beta04:recyclerview-1.1.0-beta04.aar:c3c8310eb058a660a845cf814a54f56e6f448b7855f9ccea2a5ad18189f57f69',
         'androidx.savedstate:savedstate:1.0.0:savedstate-1.0.0.aar:2510a5619c37579c9ce1a04574faaf323cd0ffe2fc4e20fa8f8f01e5bb402e83',
         'androidx.test.espresso:espresso-contrib:3.2.0:espresso-contrib-3.2.0.aar:9e43811e5845e84f2964f0032fd50cd11dca3dc8d3b0703626dd12d50433bb35',