[android] rough sketch of UI for adding contacts remotely

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -10,12 +10,17 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.Collection;
+import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
 
 @NotNullByDefault
 public interface ContactManager {
 
+	int LINK_LENGTH = 64;
+	Pattern LINK_REGEX =
+			Pattern.compile("(briar://)?([a-z2-7]{" + LINK_LENGTH + "})");
+
 	/**
 	 * Registers a hook to be called whenever a contact is added or removed.
 	 * This method should be called before
@@ -55,7 +60,7 @@ public interface ContactManager {
 	/**
 	 * Returns the static link that needs to be sent to the contact to be added.
 	 */
-	String getRemoteContactLink();
+	String getRemoteContactLink() throws DbException;
 
 	/**
 	 * Returns true if the given link is syntactically valid.
@@ -69,12 +74,12 @@ public interface ContactManager {
 	 * @param alias The alias the user has given this contact.
 	 * @return A PendingContact representing the contact to be added.
 	 */
-	PendingContact addRemoteContactRequest(String link, String alias);
+	void addRemoteContactRequest(String link, String alias);
 
 	/**
 	 * Returns a list of {@link PendingContact}s.
 	 */
-	Collection<PendingContact> getPendingContacts();
+	Collection<PendingContact> getPendingContacts() throws DbException;
 
 	/**
 	 * Removes a {@link PendingContact} that is in state

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java

@@ -5,11 +5,14 @@ import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.contact.PendingContactId;
+import org.briarproject.bramble.api.contact.event.PendingContactStateChangedEvent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.AuthorInfo;
@@ -18,17 +21,18 @@ import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.transport.KeyManager;
 
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.CopyOnWriteArrayList;
-import java.util.regex.Pattern;
+import java.util.concurrent.Executor;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
-import static java.util.Collections.emptyList;
+import static java.lang.System.currentTimeMillis;
 import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
@@ -42,11 +46,12 @@ import static org.briarproject.bramble.util.StringUtils.toUtf8;
 @NotNullByDefault
 class ContactManagerImpl implements ContactManager {
 
-	private static final int LINK_LENGTH = 64;
 	private static final String REMOTE_CONTACT_LINK =
 			"briar://" + getRandomBase32String(LINK_LENGTH);
-	private static final Pattern LINK_REGEX =
-			Pattern.compile("(briar://)?([a-z2-7]{" + LINK_LENGTH + "})");
+	// TODO remove
+	private final List<PendingContact> pendingContacts = new ArrayList<>();
+	@DatabaseExecutor
+	private final Executor dbExecutor;
 
 	private final DatabaseComponent db;
 	private final KeyManager keyManager;
@@ -54,9 +59,11 @@ class ContactManagerImpl implements ContactManager {
 	private final List<ContactHook> hooks;
 
 	@Inject
-	ContactManagerImpl(DatabaseComponent db, KeyManager keyManager,
+	ContactManagerImpl(DatabaseComponent db,
+			@DatabaseExecutor Executor dbExecutor, KeyManager keyManager,
 			IdentityManager identityManager) {
 		this.db = db;
+		this.dbExecutor = dbExecutor;
 		this.keyManager = keyManager;
 		this.identityManager = identityManager;
 		hooks = new CopyOnWriteArrayList<>();
@@ -99,9 +106,14 @@ class ContactManagerImpl implements ContactManager {
 	@Override
 	public String getRemoteContactLink() {
 		// TODO replace with real implementation
+		try {
+			Thread.sleep(1500);
+		} catch (InterruptedException ignored) {
+		}
 		return REMOTE_CONTACT_LINK;
 	}
 
+	// TODO remove
 	@SuppressWarnings("SameParameterValue")
 	private static String getRandomBase32String(int length) {
 		Random random = new Random();
@@ -120,22 +132,37 @@ class ContactManagerImpl implements ContactManager {
 	}
 
 	@Override
-	public PendingContact addRemoteContactRequest(String link, String alias) {
+	public void addRemoteContactRequest(String link, String alias) {
 		// TODO replace with real implementation
-		PendingContactId id = new PendingContactId(link.getBytes());
-		return new PendingContact(id, new byte[MAX_PUBLIC_KEY_LENGTH], alias,
-				WAITING_FOR_CONNECTION, System.currentTimeMillis());
+		dbExecutor.execute(() -> {
+			try {
+				Thread.sleep(2000);
+			} catch (InterruptedException ignored) {
+			}
+			PendingContactId id = new PendingContactId(link.getBytes());
+			PendingContact pendingContact =
+					new PendingContact(id, new byte[MAX_PUBLIC_KEY_LENGTH],
+							alias, WAITING_FOR_CONNECTION, currentTimeMillis());
+			pendingContacts.add(pendingContact);
+			Event e = new PendingContactStateChangedEvent(id,
+					WAITING_FOR_CONNECTION);
+			try {
+				db.transaction(true, txn -> txn.attach(e));
+			} catch (DbException ignored) {
+			}
+		});
 	}
 
 	@Override
 	public Collection<PendingContact> getPendingContacts() {
 		// TODO replace with real implementation
-		return emptyList();
+		return pendingContacts;
 	}
 
 	@Override
 	public void removePendingContact(PendingContact pendingContact) {
 		// TODO replace with real implementation
+		pendingContacts.remove(pendingContact);
 	}
 
 	@Override

bramble-core/src/test/java/org/briarproject/bramble/contact/ContactManagerImplTest.java

@@ -16,12 +16,14 @@ import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.transport.KeyManager;
 import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.DbExpectations;
+import org.briarproject.bramble.test.ImmediateExecutor;
 import org.jmock.Expectations;
 import org.jmock.Mockery;
 import org.junit.Test;
 
 import java.util.Collection;
 import java.util.Random;
+import java.util.concurrent.Executor;
 
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
@@ -56,8 +58,9 @@ public class ContactManagerImplTest extends BrambleMockTestCase {
 	private final ContactId contactId = contact.getId();
 
 	public ContactManagerImplTest() {
-		contactManager =
-				new ContactManagerImpl(db, keyManager, identityManager);
+		Executor dbExecutor = new ImmediateExecutor();
+		contactManager = new ContactManagerImpl(db, dbExecutor, keyManager,
+				identityManager);
 	}
 
 	@Test

briar-android/artwork/ic_nearby.svg

+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="24"
+   height="24"
+   viewBox="0 0 24 24"
+   version="1.1"
+   id="svg12"
+   sodipodi:docname="nearby.svg"
+   style="fill:none"
+   inkscape:version="0.92.3 (2405546, 2018-03-11)">
+  <metadata
+     id="metadata18">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <defs
+     id="defs16" />
+  <sodipodi:namedview
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1"
+     objecttolerance="10"
+     gridtolerance="10"
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="1920"
+     inkscape:window-height="1020"
+     id="namedview14"
+     showgrid="false"
+     inkscape:zoom="15.170655"
+     inkscape:cx="9.6488139"
+     inkscape:cy="11.430963"
+     inkscape:window-x="1440"
+     inkscape:window-y="24"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="svg12" />
+  <path
+     style="opacity:1;fill:#110000;fill-opacity:1;fill-rule:evenodd;stroke:none;stroke-width:1.37658679px;stroke-linecap:butt;stroke-linejoin:miter;stroke-opacity:1"
+     d="M 11.173062,2.4030645 C 9.9685672,2.4471125 8.7753453,2.7130268 7.6640583,3.2033016 8.187015,3.7262611 8.3967456,4.1446273 8.6059301,4.5629964 11.639055,3.412486 15.091396,4.0393524 17.497058,6.4449696 c 0.732151,0.7321412 1.359335,1.5691523 1.673062,2.5104781 0.418424,-0.2091845 0.941213,-0.3133673 1.464151,-0.3133672 h 0.104456 C 20.215788,7.3869735 19.482978,6.3401088 18.541616,5.2941863 16.528265,3.2807917 13.82295,2.3061587 11.173062,2.4030645 Z M 5.1695142,3.2316286 A 2.7193895,2.7193895 0 0 0 2.4501247,5.9510181 2.7193895,2.7193895 0 0 0 5.1695142,8.6704075 2.7193895,2.7193895 0 0 0 7.8889037,5.9510181 2.7193895,2.7193895 0 0 0 5.1695142,3.2316286 Z M 2.5404169,8.5358543 C 0.97153856,12.196552 1.7027262,16.484811 4.6313017,19.413413 c 1.8826514,1.987239 4.497171,2.930071 7.0073853,2.930071 2.510177,0 5.126431,-0.942832 7.009154,-2.930071 0.941272,-0.941362 1.672402,-2.091035 2.195341,-3.346124 h -0.104455 c -0.522939,0 -1.045818,-0.104155 -1.464151,-0.313367 -0.418423,0.941362 -0.940911,1.778328 -1.673062,2.510478 -3.242327,3.242419 -8.5770829,3.242419 -11.819429,0 C 3.27188,15.858828 2.6451458,12.406442 3.795656,9.3732707 3.377287,9.164086 2.9587814,8.9542233 2.5404169,8.5358543 Z m 9.0540081,0.8444984 a 2.9913288,2.9913284 0 0 0 -2.9902654,2.9902663 2.9913288,2.9913284 0 0 0 2.9902654,2.992036 2.9913288,2.9913284 0 0 0 2.992037,-2.992036 2.9913288,2.9913284 0 0 0 -2.992037,-2.9902663 z m 9.138991,0.423134 a 2.7193895,2.7193895 0 0 0 -2.71939,2.7193903 2.7193895,2.7193895 0 0 0 2.71939,2.719389 2.7193895,2.7193895 0 0 0 2.719389,-2.719389 2.7193895,2.7193895 0 0 0 -2.719389,-2.7193903 z"
+     id="path832-3-6"
+     inkscape:connector-curvature="0" />
+</svg>

briar-android/build.gradle

@@ -118,6 +118,7 @@ dependencies {
 	implementation 'com.google.zxing:core:3.3.3'
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:2.14.0'
 	implementation 'com.vanniktech:emoji-google:0.5.1'
+	implementation 'com.github.kobakei:MaterialFabSpeedDial:1.2.1' // later versions already use androidx
 	def glideVersion = '4.9.0'
 	implementation("com.github.bumptech.glide:glide:$glideVersion") {
 		exclude group: 'com.android.support'

briar-android/src/main/AndroidManifest.xml

@@ -425,5 +425,28 @@
 			android:launchMode="singleTask"
 			android:theme="@style/BriarTheme.NoActionBar"/>
 
+		<activity
+			android:name=".android.contact.add.remote.AddContactActivity"
+			android:theme="@style/BriarTheme"
+			android:label="@string/add_contact_remotely_title_case"
+			android:windowSoftInputMode="stateHidden|adjustResize">
+			<intent-filter>
+				<action android:name="android.intent.action.VIEW" />
+				<category android:name="android.intent.category.DEFAULT" />
+				<category android:name="android.intent.category.BROWSABLE" />
+				<data android:scheme="briar"/>
+			</intent-filter>
+			<intent-filter>
+				<action android:name="android.intent.action.SEND"/>
+				<category android:name="android.intent.category.DEFAULT"/>
+				<data android:mimeType="text/plain"/>
+			</intent-filter>
+		</activity>
+
+		<activity
+			android:name=".android.contact.add.remote.PendingRequestsActivity"
+			android:label="@string/pending_contact_requests"
+			android:theme="@style/BriarTheme"/>
+
 	</application>
 </manifest>

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

@@ -15,8 +15,12 @@ import org.briarproject.briar.android.blog.ReblogFragment;
 import org.briarproject.briar.android.blog.RssFeedImportActivity;
 import org.briarproject.briar.android.blog.RssFeedManageActivity;
 import org.briarproject.briar.android.blog.WriteBlogPostActivity;
+import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
+import org.briarproject.briar.android.contact.add.remote.LinkExchangeFragment;
 import org.briarproject.briar.android.contact.ContactListFragment;
 import org.briarproject.briar.android.contact.ContactModule;
+import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
+import org.briarproject.briar.android.contact.add.remote.PendingRequestsActivity;
 import org.briarproject.briar.android.conversation.AliasDialogFragment;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.conversation.ImageActivity;
@@ -168,6 +172,10 @@ public interface ActivityComponent {
 
 	void inject(UnlockActivity activity);
 
+	void inject(AddContactActivity activity);
+
+	void inject(PendingRequestsActivity activity);
+
 	// Fragments
 	void inject(AuthorNameFragment fragment);
 
@@ -191,6 +199,10 @@ public interface ActivityComponent {
 
 	void inject(KeyAgreementFragment fragment);
 
+	void inject(LinkExchangeFragment fragment);
+
+	void inject(NicknameFragment fragment);
+
 	void inject(ContactChooserFragment fragment);
 
 	void inject(ShareForumFragment fragment);

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -3,22 +3,24 @@ package org.briarproject.briar.android.contact;
 import android.content.Intent;
 import android.os.Bundle;
 import android.support.annotation.UiThread;
+import android.support.design.widget.FloatingActionButton;
+import android.support.design.widget.Snackbar;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.ActivityOptionsCompat;
+import android.support.v4.content.ContextCompat;
 import android.support.v4.util.Pair;
 import android.support.v7.widget.LinearLayoutManager;
 import android.view.LayoutInflater;
-import android.view.Menu;
-import android.view.MenuInflater;
-import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.TextView;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
 import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
+import org.briarproject.bramble.api.contact.event.PendingContactStateChangedEvent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.event.Event;
@@ -32,6 +34,8 @@ import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.contact.BaseContactListAdapter.OnContactClickListener;
+import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
+import org.briarproject.briar.android.contact.add.remote.PendingRequestsActivity;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
@@ -49,11 +53,16 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import io.github.kobakei.materialfabspeeddial.FabSpeedDial;
+import io.github.kobakei.materialfabspeeddial.FabSpeedDial.OnMenuItemClickListener;
+
 import static android.os.Build.VERSION.SDK_INT;
+import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
 import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static android.support.v4.view.ViewCompat.getTransitionName;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -62,7 +71,8 @@ import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ContactListFragment extends BaseFragment implements EventListener {
+public class ContactListFragment extends BaseFragment implements EventListener,
+		OnMenuItemClickListener {
 
 	public static final String TAG = ContactListFragment.class.getName();
 	private static final Logger LOG = Logger.getLogger(TAG);
@@ -76,6 +86,7 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 
 	private ContactListAdapter adapter;
 	private BriarRecyclerView list;
+	private Snackbar snackbar;
 
 	// Fields that are accessed from background threads must be volatile
 	@Inject
@@ -107,7 +118,12 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 			@Nullable Bundle savedInstanceState) {
 		requireNonNull(getActivity()).setTitle(R.string.contact_list_button);
 
-		View contentView = inflater.inflate(R.layout.list, container, false);
+		View contentView =
+				inflater.inflate(R.layout.fragment_contact_list, container,
+						false);
+
+		FabSpeedDial speedDialView = contentView.findViewById(R.id.speedDial);
+		speedDialView.addOnMenuItemClickListener(this);
 
 		OnContactClickListener<ContactListItem> onContactClickListener =
 				(view, item) -> {
@@ -146,26 +162,30 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 		list.setEmptyText(getString(R.string.no_contacts));
 		list.setEmptyAction(getString(R.string.no_contacts_action));
 
-		return contentView;
-	}
+		// TODO UiUtils helper method?
+		snackbar = Snackbar.make(contentView,
+				R.string.pending_contact_requests_snackbar, LENGTH_INDEFINITE);
+		snackbar.getView().setBackgroundResource(R.color.briar_primary);
+		snackbar.setAction(R.string.show, v -> startActivity(
+				new Intent(getContext(), PendingRequestsActivity.class)));
+		snackbar.setActionTextColor(ContextCompat
+				.getColor(getContext(), R.color.briar_button_text_positive));
 
-	@Override
-	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
-		inflater.inflate(R.menu.contact_list_actions, menu);
-		super.onCreateOptionsMenu(menu, inflater);
+		return contentView;
 	}
 
 	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
-		// Handle presses on the action bar items
-		switch (item.getItemId()) {
-			case R.id.action_add_contact:
+	public void onMenuItemClick(FloatingActionButton fab, @Nullable TextView v,
+			int itemId) {
+		switch (itemId) {
+			case R.id.action_add_contact_nearby:
 				Intent intent =
 						new Intent(getContext(), ContactExchangeActivity.class);
 				startActivity(intent);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+				return;
+			case R.id.action_add_contact_remotely:
+				startActivity(
+						new Intent(getContext(), AddContactActivity.class));
 		}
 	}
 
@@ -176,9 +196,24 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 		notificationManager.clearAllContactNotifications();
 		notificationManager.clearAllIntroductionNotifications();
 		loadContacts();
+		checkForPendingContacts();
 		list.startPeriodicUpdate();
 	}
 
+	private void checkForPendingContacts() {
+		listener.runOnDbThread(() -> {
+			try {
+				if (contactManager.getPendingContacts().isEmpty()) {
+					runOnUiThreadUnlessDestroyed(() -> snackbar.dismiss());
+				} else {
+					runOnUiThreadUnlessDestroyed(() -> snackbar.show());
+				}
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
 	@Override
 	public void onStop() {
 		super.onStop();
@@ -232,6 +267,7 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 		if (e instanceof ContactAddedEvent) {
 			LOG.info("Contact added, reloading");
 			loadContacts();
+			checkForPendingContacts();
 		} else if (e instanceof ContactConnectedEvent) {
 			setConnected(((ContactConnectedEvent) e).getContactId(), true);
 		} else if (e instanceof ContactDisconnectedEvent) {
@@ -245,6 +281,13 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 					(ConversationMessageReceivedEvent) e;
 			ConversationMessageHeader h = p.getMessageHeader();
 			updateItem(p.getContactId(), h);
+		} else if (e instanceof PendingContactStateChangedEvent) {
+			PendingContactStateChangedEvent pe =
+					(PendingContactStateChangedEvent) e;
+			// only re-check pending contacts for initial state
+			if (pe.getPendingContactState() == WAITING_FOR_CONNECTION) {
+				checkForPendingContacts();
+			}
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/AddContactActivity.java

+package org.briarproject.briar.android.contact.add.remote;
+
+import android.arch.lifecycle.ViewModelProvider;
+import android.arch.lifecycle.ViewModelProviders;
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.v7.app.ActionBar;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+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.activity.BriarActivity;
+import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import static android.content.Intent.ACTION_SEND;
+import static android.content.Intent.ACTION_VIEW;
+import static android.content.Intent.EXTRA_TEXT;
+import static android.widget.Toast.LENGTH_LONG;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddContactActivity extends BriarActivity implements
+		BaseFragmentListener {
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+		setContentView(R.layout.activity_fragment_container);
+
+		ActionBar ab = getSupportActionBar();
+		if (ab != null) {
+			ab.setDisplayHomeAsUpEnabled(true);
+		}
+
+		AddContactViewModel viewModel =
+				ViewModelProviders.of(this, viewModelFactory)
+						.get(AddContactViewModel.class);
+		viewModel.getRemoteLinkEntered().observe(this, entered -> {
+			if (entered != null && entered) {
+				NicknameFragment f = new NicknameFragment();
+				showNextFragment(f);
+			}
+		});
+
+		Intent i = getIntent();
+		if (i != null) {
+			String action = i.getAction();
+			if (ACTION_SEND.equals(action) || ACTION_VIEW.equals(action)) {
+				String text = i.getStringExtra(EXTRA_TEXT);
+				if (text != null) {
+					if (viewModel.isValidRemoteContactLink(text)) {
+						viewModel.setRemoteContactLink(text);
+					} else {
+						Toast.makeText(this, R.string.invalid_link, LENGTH_LONG)
+								.show();
+					}
+				}
+				String uri = i.getDataString();
+				if (uri != null) {
+					if (viewModel.isValidRemoteContactLink(uri)) {
+						viewModel.setRemoteContactLink(uri);
+					} else {
+						Toast.makeText(this, R.string.invalid_link, LENGTH_LONG)
+								.show();
+					}
+				}
+			}
+		}
+		if (state == null) {
+			showInitialFragment(new LinkExchangeFragment());
+		}
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		switch (item.getItemId()) {
+			case android.R.id.home:
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
+		}
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/AddContactViewModel.java

+package org.briarproject.briar.android.contact.add.remote;
+
+import android.app.Application;
+import android.arch.lifecycle.AndroidViewModel;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.logging.Logger.getLogger;
+
+@NotNullByDefault
+public class AddContactViewModel extends AndroidViewModel {
+
+	private static Logger LOG = getLogger(AddContactViewModel.class.getName());
+
+	private final ContactManager contactManager;
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+
+	private final MutableLiveData<String> ourLink = new MutableLiveData<>();
+	private final MutableLiveData<Boolean> remoteLinkEntered =
+			new MutableLiveData<>();
+	@Nullable
+	private String remoteContactLink;
+
+	@Inject
+	public AddContactViewModel(@NonNull Application application,
+			ContactManager contactManager,
+			@DatabaseExecutor Executor dbExecutor) {
+		super(application);
+		this.contactManager = contactManager;
+		this.dbExecutor = dbExecutor;
+		loadOurLink();
+	}
+
+	private void loadOurLink() {
+		dbExecutor.execute(() -> {
+			try {
+				ourLink.postValue(contactManager.getRemoteContactLink());
+			} catch (DbException e) {
+				throw new AssertionError(e);
+			}
+		});
+	}
+
+	LiveData<String> getOurLink() {
+		return ourLink;
+	}
+
+	void setRemoteContactLink(String link) {