Merge branch '1872-key-agreement' into 'master'

Finish migrating KeyAgreementActivity to ViewModel

Closes #1982 and #1872

See merge request briar/briar!1357

.gitignore

@@ -18,6 +18,7 @@ local.properties
 
 # Android Studio
 .idea/*
+!.idea/inspectionProfiles/
 !.idea/runConfigurations/
 !.idea/codeStyleSettings.xml
 !.idea/codeStyles

.idea/inspectionProfiles/Project_Default.xml

@@ -0,0 +1,10 @@
+<component name="InspectionProjectProfileManager">
+  <profile version="1.0">
+    <option name="myName" value="Project Default" />
+    <inspection_tool class="WeakerAccess" enabled="true" level="WARNING" enabled_by_default="true">
+      <option name="SUGGEST_PACKAGE_LOCAL_FOR_MEMBERS" value="true" />
+      <option name="SUGGEST_PACKAGE_LOCAL_FOR_TOP_CLASSES" value="true" />
+      <option name="SUGGEST_PRIVATE_FOR_INNERS" value="true" />
+    </inspection_tool>
+  </profile>
+</component>

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTransport.java

@@ -34,12 +34,12 @@ class KeyAgreementTransport {
 			Logger.getLogger(KeyAgreementTransport.class.getName());
 
 	// Accept records with current protocol version, known record type
-	private static Predicate<Record> ACCEPT = r ->
+	private static final Predicate<Record> ACCEPT = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					isKnownRecordType(r.getRecordType());
 
 	// Ignore records with current protocol version, unknown record type
-	private static Predicate<Record> IGNORE = r ->
+	private static final Predicate<Record> IGNORE = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					!isKnownRecordType(r.getRecordType());
 

briar-android/src/main/AndroidManifest.xml

@@ -342,7 +342,7 @@
 		</activity>
 
 		<activity
-			android:name="org.briarproject.briar.android.keyagreement.ContactExchangeActivity"
+			android:name="org.briarproject.briar.android.contact.add.nearby.AddNearbyContactActivity"
 			android:label="@string/add_contact_title"
 			android:parentActivityName="org.briarproject.briar.android.navdrawer.NavDrawerActivity"
 			android:theme="@style/BriarTheme.NoActionBar">

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

@@ -33,9 +33,9 @@ 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.contact.add.nearby.AddNearbyContactModule;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.introduction.IntroductionModule;
-import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.logging.LoggingModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
@@ -77,7 +77,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 @Module(includes = {
 		SetupModule.class,
 		DozeHelperModule.class,
-		ContactExchangeModule.class,
+		AddNearbyContactModule.class,
 		LoggingModule.class,
 		LoginModule.class,
 		NavDrawerModule.class,

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

@@ -19,6 +19,10 @@ 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.ContactListFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactActivity;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactErrorFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactFragment;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactIntroFragment;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.LinkExchangeFragment;
 import org.briarproject.briar.android.contact.add.remote.NicknameFragment;
@@ -34,10 +38,6 @@ import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.introduction.IntroductionMessageFragment;
-import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
-import org.briarproject.briar.android.keyagreement.ContactExchangeErrorFragment;
-import org.briarproject.briar.android.keyagreement.KeyAgreementActivity;
-import org.briarproject.briar.android.keyagreement.KeyAgreementFragment;
 import org.briarproject.briar.android.login.ChangePasswordActivity;
 import org.briarproject.briar.android.login.OpenDatabaseFragment;
 import org.briarproject.briar.android.login.PasswordFragment;
@@ -105,9 +105,7 @@ public interface ActivityComponent {
 
 	void inject(PanicPreferencesActivity activity);
 
-	void inject(ContactExchangeActivity activity);
+	void inject(AddNearbyContactActivity activity);
-
-	void inject(KeyAgreementActivity activity);
 
 	void inject(ConversationActivity activity);
 
@@ -203,7 +201,9 @@ public interface ActivityComponent {
 
 	void inject(FeedFragment fragment);
 
-	void inject(KeyAgreementFragment fragment);
+	void inject(AddNearbyContactIntroFragment fragment);
+
+	void inject(AddNearbyContactFragment fragment);
 
 	void inject(LinkExchangeFragment fragment);
 
@@ -221,7 +221,7 @@ public interface ActivityComponent {
 
 	void inject(ScreenFilterDialogFragment fragment);
 
-	void inject(ContactExchangeErrorFragment fragment);
+	void inject(AddNearbyContactErrorFragment fragment);
 
 	void inject(AliasDialogFragment aliasDialogFragment);
 

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

@@ -8,9 +8,7 @@ public interface RequestCodes {
 	int REQUEST_SHARE_FORUM = 4;
 	int REQUEST_SHARE_BLOG = 6;
 	int REQUEST_RINGTONE = 7;
-	int REQUEST_PERMISSION_CAMERA_LOCATION = 8;
 	int REQUEST_DOZE_WHITELISTING = 9;
-	int REQUEST_BLUETOOTH_DISCOVERABLE = 10;
 	int REQUEST_UNLOCK = 11;
 	int REQUEST_KEYGUARD_UNLOCK = 12;
 	int REQUEST_ATTACH_IMAGE = 13;

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

@@ -15,11 +15,11 @@ 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.contact.add.nearby.AddNearbyContactActivity;
 import org.briarproject.briar.android.contact.add.remote.AddContactActivity;
 import org.briarproject.briar.android.contact.add.remote.PendingContactListActivity;
 import org.briarproject.briar.android.conversation.ConversationActivity;
 import org.briarproject.briar.android.fragment.BaseFragment;
-import org.briarproject.briar.android.keyagreement.ContactExchangeActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 
@@ -125,7 +125,8 @@ public class ContactListFragment extends BaseFragment
 		switch (itemId) {
 			case R.id.action_add_contact_nearby:
 				Intent intent =
-						new Intent(getContext(), ContactExchangeActivity.class);
+						new Intent(getContext(),
+								AddNearbyContactActivity.class);
 				startActivity(intent);
 				return;
 			case R.id.action_add_contact_remotely:

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddContactState.java

@@ -0,0 +1,76 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.graphics.Bitmap;
+
+import org.briarproject.bramble.api.identity.Author;
+
+import androidx.annotation.Nullable;
+
+abstract class AddContactState {
+
+	static class KeyAgreementListening extends AddContactState {
+		final Bitmap qrCode;
+
+		KeyAgreementListening(Bitmap qrCode) {
+			this.qrCode = qrCode;
+		}
+	}
+
+	static class QrCodeScanned extends AddContactState {
+	}
+
+	static class KeyAgreementWaiting extends AddContactState {
+	}
+
+	static class KeyAgreementStarted extends AddContactState {
+	}
+
+	static class ContactExchangeStarted extends AddContactState {
+	}
+
+	static class ContactExchangeFinished extends AddContactState {
+		final ContactExchangeResult result;
+
+		ContactExchangeFinished(ContactExchangeResult result) {
+			this.result = result;
+		}
+	}
+
+	static class Failed extends AddContactState {
+		/**
+		 * Non-null if failed due to the scanned QR code version.
+		 * True if the app producing the code is too old.
+		 * False if the scanning app is too old.
+		 */
+		@Nullable
+		final Boolean qrCodeTooOld;
+
+		Failed(@Nullable Boolean qrCodeTooOld) {
+			this.qrCodeTooOld = qrCodeTooOld;
+		}
+
+		Failed() {
+			this(null);
+		}
+	}
+
+	abstract static class ContactExchangeResult {
+		static class Success extends ContactExchangeResult {
+			final Author remoteAuthor;
+
+			Success(Author remoteAuthor) {
+				this.remoteAuthor = remoteAuthor;
+			}
+		}
+
+		static class Error extends ContactExchangeResult {
+			@Nullable
+			final Author duplicateAuthor;
+
+			Error(@Nullable Author duplicateAuthor) {
+				this.duplicateAuthor = duplicateAuthor;
+			}
+		}
+	} // end ContactExchangeResult
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactActivity.java

@@ -0,0 +1,193 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.view.MenuItem;
+import android.widget.Toast;
+
+import org.briarproject.bramble.api.identity.Author;
+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.contact.add.nearby.AddContactState.ContactExchangeFinished;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.Failed;
+import org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
+import org.briarproject.briar.android.util.RequestBluetoothDiscoverable;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.appcompat.widget.Toolbar;
+import androidx.fragment.app.FragmentManager;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.ACCEPTED;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactActivity extends BriarActivity
+		implements BaseFragmentListener {
+
+	private static final Logger LOG =
+			getLogger(AddNearbyContactActivity.class.getName());
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private final ActivityResultLauncher<Integer> bluetoothLauncher =
+			registerForActivityResult(new RequestBluetoothDiscoverable(),
+					this::onBluetoothDiscoverableResult);
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
+		setContentView(R.layout.activity_fragment_container_toolbar);
+		Toolbar toolbar = findViewById(R.id.toolbar);
+		setSupportActionBar(toolbar);
+		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
+		if (state == null) {
+			showInitialFragment(AddNearbyContactIntroFragment.newInstance());
+		}
+		viewModel.getRequestBluetoothDiscoverable().observeEvent(this, r ->
+				requestBluetoothDiscoverable()); // never false
+		viewModel.getShowQrCodeFragment().observeEvent(this, show -> {
+			if (show) showQrCodeFragment();
+		});
+		requireNonNull(getSupportActionBar())
+				.setTitle(R.string.add_contact_title);
+		viewModel.getState()
+				.observe(this, this::onAddContactStateChanged);
+	}
+
+	private void onBluetoothDiscoverableResult(boolean discoverable) {
+		if (discoverable) {
+			LOG.info("Bluetooth discoverability was accepted");
+			viewModel.setBluetoothDecision(ACCEPTED);
+		} else {
+			LOG.info("Bluetooth discoverability was refused");
+			viewModel.setBluetoothDecision(REFUSED);
+		}
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
+		}
+		return super.onOptionsItemSelected(item);
+	}
+
+	@Override
+	public void onBackPressed() {
+		if (viewModel.getState().getValue() instanceof Failed) {
+			// Re-create this activity when going back in failed state.
+			// This will also re-create the ViewModel, so we start fresh.
+			Intent i = new Intent(this, AddNearbyContactActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			startActivity(i);
+		} else {
+			super.onBackPressed();
+		}
+	}
+
+	private void requestBluetoothDiscoverable() {
+		Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+		if (i.resolveActivity(getPackageManager()) != null) {
+			LOG.info("Asking for Bluetooth discoverability");
+			viewModel.setBluetoothDecision(BluetoothDecision.WAITING);
+			bluetoothLauncher.launch(120); // 2min discoverable
+		} else {
+			viewModel.setBluetoothDecision(BluetoothDecision.NO_ADAPTER);
+		}
+	}
+
+	private void showQrCodeFragment() {
+		// FIXME #824
+		FragmentManager fm = getSupportFragmentManager();
+		if (fm.findFragmentByTag(AddNearbyContactFragment.TAG) == null) {
+			BaseFragment f = AddNearbyContactFragment.newInstance();
+			fm.beginTransaction()
+					.replace(R.id.fragmentContainer, f, f.getUniqueTag())
+					.addToBackStack(f.getUniqueTag())
+					.commit();
+		}
+	}
+
+	private void onAddContactStateChanged(@Nullable AddContactState state) {
+		if (state instanceof ContactExchangeFinished) {
+			ContactExchangeResult result =
+					((ContactExchangeFinished) state).result;
+			onContactExchangeResult(result);
+		} else if (state instanceof Failed) {
+			Boolean qrCodeTooOld = ((Failed) state).qrCodeTooOld;
+			onAddingContactFailed(qrCodeTooOld);
+		}
+	}
+
+	private void onContactExchangeResult(ContactExchangeResult result) {
+		if (result instanceof ContactExchangeResult.Success) {
+			Author remoteAuthor =
+					((ContactExchangeResult.Success) result).remoteAuthor;
+			String contactName = remoteAuthor.getName();
+			String text = getString(R.string.contact_added_toast, contactName);
+			Toast.makeText(this, text, LENGTH_LONG).show();
+			supportFinishAfterTransition();
+		} else if (result instanceof ContactExchangeResult.Error) {
+			Author duplicateAuthor =
+					((ContactExchangeResult.Error) result).duplicateAuthor;
+			if (duplicateAuthor == null) {
+				showErrorFragment();
+			} else {
+				String contactName = duplicateAuthor.getName();
+				String text =
+						getString(R.string.contact_already_exists, contactName);
+				Toast.makeText(this, text, LENGTH_LONG).show();
+				supportFinishAfterTransition();
+			}
+		} else throw new AssertionError();
+	}
+
+	private void onAddingContactFailed(@Nullable Boolean qrCodeTooOld) {
+		if (qrCodeTooOld == null) {
+			showErrorFragment();
+		} else {
+			String msg;
+			if (qrCodeTooOld) {
+				msg = getString(R.string.qr_code_too_old,
+						getString(R.string.app_name));
+			} else {
+				msg = getString(R.string.qr_code_too_new,
+						getString(R.string.app_name));
+			}
+			showNextFragment(AddNearbyContactErrorFragment.newInstance(msg));
+		}
+	}
+
+	private void showErrorFragment() {
+		showNextFragment(new AddNearbyContactErrorFragment());
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactErrorFragment.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.content.Intent;
 import android.os.Bundle;
@@ -15,8 +15,11 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.util.UiUtils;
 
+import javax.inject.Inject;
+
 import androidx.annotation.Nullable;
 import androidx.fragment.app.FragmentActivity;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.view.View.GONE;
@@ -24,14 +27,19 @@ import static org.briarproject.briar.android.util.UiUtils.onSingleLinkClick;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ContactExchangeErrorFragment extends BaseFragment {
+public class AddNearbyContactErrorFragment extends BaseFragment {
 
 	public static final String TAG =
-			ContactExchangeErrorFragment.class.getName();
+			AddNearbyContactErrorFragment.class.getName();
 	private static final String ERROR_MSG = "errorMessage";
 
-	public static ContactExchangeErrorFragment newInstance(String errorMsg) {
+	@Inject
-		ContactExchangeErrorFragment f = new ContactExchangeErrorFragment();
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+
+	public static AddNearbyContactErrorFragment newInstance(String errorMsg) {
+		AddNearbyContactErrorFragment f = new AddNearbyContactErrorFragment();
 		Bundle args = new Bundle();
 		args.putString(ERROR_MSG, errorMsg);
 		f.setArguments(args);
@@ -46,6 +54,8 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
 	}
 
 	@Nullable
@@ -72,7 +82,7 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		tryAgain.setOnClickListener(view -> {
 			// Recreate the activity so we return to the intro fragment
 			FragmentActivity activity = requireActivity();
-			Intent i = new Intent(activity, ContactExchangeActivity.class);
+			Intent i = new Intent(activity, AddNearbyContactActivity.class);
 			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
 			activity.startActivity(i);
 		});
@@ -81,6 +91,15 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		return v;
 	}
 
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		// We don't do this in AddNearbyContactFragment#onDestroy()
+		// because it gets called when creating AddNearbyContactFragment
+		// in landscape orientation to force portrait orientation.
+		viewModel.stopListening();
+	}
+
 	private void triggerFeedback() {
 		UiUtils.triggerFeedback(requireContext());
 		finish();

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactFragment.java

@@ -0,0 +1,190 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.graphics.Bitmap;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.LinearLayout;
+import android.widget.LinearLayout.LayoutParams;
+import android.widget.TextView;
+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.contact.add.nearby.AddContactState.ContactExchangeStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.Failed;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.QrCodeScanned;
+import org.briarproject.briar.android.fragment.BaseFragment;
+import org.briarproject.briar.android.view.QrCodeView;
+
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
+import static android.widget.LinearLayout.HORIZONTAL;
+import static android.widget.Toast.LENGTH_LONG;
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactFragment extends BaseFragment
+		implements QrCodeView.FullscreenListener {
+
+	static final String TAG = AddNearbyContactFragment.class.getName();
+
+	private static final Logger LOG = Logger.getLogger(TAG);
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private CameraView cameraView;
+	private LinearLayout cameraOverlay;
+	private View statusView;
+	private QrCodeView qrCodeView;
+	private TextView status;
+
+	public static AddNearbyContactFragment newInstance() {
+		Bundle args = new Bundle();
+		AddNearbyContactFragment fragment = new AddNearbyContactFragment();
+		fragment.setArguments(args);
+		return fragment;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		return inflater.inflate(R.layout.fragment_keyagreement_qr, container,
+				false);
+	}
+
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		cameraView = view.findViewById(R.id.camera_view);
+		cameraView.setPreviewConsumer(viewModel.getQrCodeDecoder());
+		cameraOverlay = view.findViewById(R.id.camera_overlay);
+		statusView = view.findViewById(R.id.status_container);
+		status = view.findViewById(R.id.connect_status);
+		qrCodeView = view.findViewById(R.id.qr_code_view);
+		qrCodeView.setFullscreenListener(this);
+
+		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
+
+		viewModel.getState().observe(getViewLifecycleOwner(),
+				this::onAddContactStateChanged);
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		try {
+			cameraView.start();
+		} catch (CameraException e) {
+			logCameraExceptionAndFinish(e);
+		}
+	}
+
+	@Override
+	public void onStop() {
+		super.onStop();
+		try {
+			cameraView.stop();
+		} catch (CameraException e) {
+			logCameraExceptionAndFinish(e);
+		}
+	}
+
+	@Override
+	public void setFullscreen(boolean fullscreen) {
+		LinearLayout.LayoutParams statusParams, qrCodeParams;
+		if (fullscreen) {
+			// Grow the QR code view to fill its parent
+			statusParams = new LayoutParams(0, 0, 0f);
+			qrCodeParams = new LayoutParams(MATCH_PARENT, MATCH_PARENT, 1f);
+		} else {
+			// Shrink the QR code view to fill half its parent
+			if (cameraOverlay.getOrientation() == HORIZONTAL) {
+				statusParams = new LayoutParams(0, MATCH_PARENT, 1f);
+				qrCodeParams = new LayoutParams(0, MATCH_PARENT, 1f);
+			} else {
+				statusParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+				qrCodeParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+			}
+		}
+		statusView.setLayoutParams(statusParams);
+		qrCodeView.setLayoutParams(qrCodeParams);
+		cameraOverlay.invalidate();
+	}
+
+	@UiThread
+	private void onAddContactStateChanged(@Nullable AddContactState state) {
+		if (state instanceof AddContactState.KeyAgreementListening) {
+			Bitmap qrCode =
+					((AddContactState.KeyAgreementListening) state).qrCode;
+			qrCodeView.setQrCode(qrCode);
+		} else if (state instanceof QrCodeScanned) {
+			try {
+				cameraView.stop();
+			} catch (CameraException e) {
+				logCameraExceptionAndFinish(e);
+			}
+			cameraView.setVisibility(INVISIBLE);
+			statusView.setVisibility(VISIBLE);
+			status.setText(R.string.connecting_to_device);
+		} else if (state instanceof KeyAgreementWaiting) {
+			status.setText(R.string.waiting_for_contact_to_scan);
+		} else if (state instanceof KeyAgreementStarted) {
+			qrCodeView.setVisibility(INVISIBLE);
+			status.setText(R.string.authenticating_with_device);
+		} else if (state instanceof ContactExchangeStarted) {
+			status.setText(R.string.exchanging_contact_details);
+		} else if (state instanceof Failed) {
+			// the activity will replace this fragment with an error fragment
+			statusView.setVisibility(INVISIBLE);
+			cameraView.setVisibility(INVISIBLE);
+		}
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@UiThread
+	private void logCameraExceptionAndFinish(CameraException e) {
+		logException(LOG, WARNING, e);
+		Toast.makeText(getActivity(), R.string.camera_error,
+				LENGTH_LONG).show();
+		finish();
+	}
+
+	@Override
+	protected void finish() {
+		requireActivity().getSupportFragmentManager().popBackStack();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactIntroFragment.java

@@ -0,0 +1,106 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ScrollView;
+
+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.fragment.BaseFragment;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import androidx.activity.result.ActivityResultLauncher;
+import androidx.activity.result.contract.ActivityResultContracts.RequestMultiplePermissions;
+import androidx.lifecycle.ViewModelProvider;
+
+import static android.view.View.FOCUS_DOWN;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class AddNearbyContactIntroFragment extends BaseFragment {
+
+	public static final String TAG =
+			AddNearbyContactIntroFragment.class.getName();
+
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
+
+	private AddNearbyContactViewModel viewModel;
+	private AddNearbyContactPermissionManager permissionManager;
+
+	private ScrollView scrollView;
+
+	private final ActivityResultLauncher<String[]> permissionLauncher =
+			registerForActivityResult(new RequestMultiplePermissions(), r -> {
+				permissionManager.onRequestPermissionResult(r);
+				if (permissionManager.checkPermissions()) {
+					viewModel.showQrCodeFragmentIfAllowed();
+				}
+			});
+
+	public static AddNearbyContactIntroFragment newInstance() {
+		Bundle args = new Bundle();
+		AddNearbyContactIntroFragment
+				fragment = new AddNearbyContactIntroFragment();
+		fragment.setArguments(args);
+		return fragment;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(AddNearbyContactViewModel.class);
+		permissionManager = new AddNearbyContactPermissionManager(
+				requireActivity(), permissionLauncher::launch,
+				viewModel.isBluetoothSupported());
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+
+		View v = inflater.inflate(R.layout.fragment_keyagreement_id, container,
+				false);
+		scrollView = v.findViewById(R.id.scrollView);
+		View button = v.findViewById(R.id.continueButton);
+		button.setOnClickListener(view -> {
+			viewModel.onContinueClicked();
+			if (permissionManager.checkPermissions()) {
+				viewModel.showQrCodeFragmentIfAllowed();
+			}
+		});
+		return v;
+	}
+
+	@Override
+	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
+		super.onViewCreated(view, savedInstanceState);
+		// We don't do this in AddNearbyContactFragment#onDestroy()
+		// because it gets called when creating AddNearbyContactFragment
+		// in landscape orientation to force portrait orientation.
+		viewModel.stopListening();
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		// Permissions may have been granted manually while we were stopped
+		permissionManager.resetPermissions();
+		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
+	}
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactModule.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
@@ -8,12 +8,12 @@ import dagger.Module;
 import dagger.multibindings.IntoMap;
 
 @Module
-public abstract class ContactExchangeModule {
+public abstract class AddNearbyContactModule {
 
 	@Binds
 	@IntoMap
-	@ViewModelKey(ContactExchangeViewModel.class)
+	@ViewModelKey(AddNearbyContactViewModel.class)
 	abstract ViewModel bindContactExchangeViewModel(
-			ContactExchangeViewModel contactExchangeViewModel);
+			AddNearbyContactViewModel addNearbyContactViewModel);
 
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactPermissionManager.java

@@ -0,0 +1,201 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.content.ActivityNotFoundException;
+import android.content.Context;
+import android.content.Intent;
+import android.location.LocationManager;
+import android.widget.Toast;
+
+import org.briarproject.briar.R;
+
+import java.util.Map;
+
+import androidx.annotation.StringRes;
+import androidx.appcompat.app.AlertDialog;
+import androidx.core.util.Consumer;
+import androidx.fragment.app.FragmentActivity;
+
+import static android.Manifest.permission.ACCESS_FINE_LOCATION;
+import static android.Manifest.permission.CAMERA;
+import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS;
+import static android.widget.Toast.LENGTH_LONG;
+import static androidx.core.app.ActivityCompat.shouldShowRequestPermissionRationale;
+import static androidx.core.content.ContextCompat.checkSelfPermission;
+import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
+
+class AddNearbyContactPermissionManager {
+
+	private enum Permission {
+		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
+	}
+
+	private Permission cameraPermission = Permission.UNKNOWN;
+	private Permission locationPermission = Permission.UNKNOWN;
+
+	private final FragmentActivity ctx;
+	private final Consumer<String[]> requestPermissions;
+	private final boolean isBluetoothSupported;
+
+	AddNearbyContactPermissionManager(FragmentActivity ctx,
+			Consumer<String[]> requestPermissions,
+			boolean isBluetoothSupported) {
+		this.ctx = ctx;
+		this.requestPermissions = requestPermissions;
+		this.isBluetoothSupported = isBluetoothSupported;
+	}
+
+	void resetPermissions() {
+		cameraPermission = Permission.UNKNOWN;
+		locationPermission = Permission.UNKNOWN;
+	}
+
+	/**
+	 * @return true if location is enabled,
+	 * or it isn't required due to this being a SDK < 28 device.
+	 */
+	static boolean isLocationEnabled(Context ctx) {
+		if (SDK_INT >= 28) {
+			LocationManager lm = ctx.getSystemService(LocationManager.class);
+			return lm.isLocationEnabled();
+		} else {
+			return true;
+		}
+	}
+
+	static boolean areEssentialPermissionsGranted(Context ctx,
+			boolean isBluetoothSupported) {
+		int ok = PERMISSION_GRANTED;
+		return checkSelfPermission(ctx, CAMERA) == ok &&
+				(SDK_INT < 23 ||
+						checkSelfPermission(ctx, ACCESS_FINE_LOCATION) == ok ||
+						!isBluetoothSupported);
+	}
+
+	private boolean areEssentialPermissionsGranted() {
+		return cameraPermission == Permission.GRANTED &&
+				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
+						!isBluetoothSupported);
+	}
+
+	boolean checkPermissions() {
+		boolean locationEnabled = isLocationEnabled(ctx);
+		if (locationEnabled && areEssentialPermissionsGranted()) return true;
+		// If an essential permission has been permanently denied, ask the
+		// user to change the setting
+		if (cameraPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(R.string.permission_camera_title,
+					R.string.permission_camera_denied_body);
+			return false;
+		}
+		if (isBluetoothSupported &&
+				locationPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(R.string.permission_location_title,
+					R.string.permission_location_denied_body);
+			return false;
+		}
+		// Should we show the rationale for one or both permissions?
+		if (cameraPermission == Permission.SHOW_RATIONALE &&
+				locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_camera_location_title,
+					R.string.permission_camera_location_request_body);
+		} else if (cameraPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_camera_title,
+					R.string.permission_camera_request_body);
+		} else if (locationPermission == Permission.SHOW_RATIONALE) {
+			showRationale(R.string.permission_location_title,
+					R.string.permission_location_request_body);
+		} else if (isLocationEnabled(ctx)) {
+			requestPermissions();
+		} else {
+			showLocationDialog(ctx);
+		}
+		return false;
+	}
+
+	private void showDenialDialog(@StringRes int title, @StringRes int body) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setPositiveButton(R.string.ok, getGoToSettingsListener(ctx));
+		builder.setNegativeButton(R.string.cancel,
+				(dialog, which) -> ctx.supportFinishAfterTransition());
+		builder.show();
+	}
+
+	private void showRationale(@StringRes int title, @StringRes int body) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setNeutralButton(R.string.continue_button,
+				(dialog, which) -> requestPermissions());
+		builder.show();
+	}
+
+	private static void showLocationDialog(Context ctx) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		builder.setTitle(R.string.permission_location_setting_title);
+		builder.setMessage(R.string.permission_location_setting_body);
+		builder.setNegativeButton(R.string.cancel, null);
+		builder.setPositiveButton(R.string.permission_location_setting_button,
+				(dialog, which) -> {
+					Intent i = new Intent(ACTION_LOCATION_SOURCE_SETTINGS);
+					try {
+						ctx.startActivity(i);
+					} catch (ActivityNotFoundException e) {
+						Toast.makeText(ctx, R.string.error_start_activity,
+								LENGTH_LONG).show();
+					}
+				});
+		builder.show();
+	}
+
+	private void requestPermissions() {
+		String[] permissions;
+		if (isBluetoothSupported) {
+			permissions = new String[] {CAMERA, ACCESS_FINE_LOCATION};
+		} else {
+			permissions = new String[] {CAMERA};
+		}
+		requestPermissions.accept(permissions);
+	}
+
+	void onRequestPermissionResult(Map<String, Boolean> result) {
+		if (gotPermission(CAMERA, result)) {
+			cameraPermission = Permission.GRANTED;
+		} else if (shouldShowRationale(CAMERA)) {
+			cameraPermission = Permission.SHOW_RATIONALE;
+		} else {
+			cameraPermission = Permission.PERMANENTLY_DENIED;
+		}
+		if (isBluetoothSupported) {
+			if (gotPermission(ACCESS_FINE_LOCATION, result)) {
+				locationPermission = Permission.GRANTED;
+			} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
+				locationPermission = Permission.SHOW_RATIONALE;
+			} else {
+				locationPermission = Permission.PERMANENTLY_DENIED;
+			}
+		}
+	}
+
+	private boolean gotPermission(String permission,
+			Map<String, Boolean> result) {
+		Boolean permissionResult = result.get(permission);
+		return permissionResult == null ?
+				isGranted(permission) : permissionResult;
+	}
+
+	private boolean isGranted(String permission) {
+		return checkSelfPermission(ctx, permission) == PERMISSION_GRANTED;
+	}
+
+	private boolean shouldShowRationale(String permission) {
+		return shouldShowRequestPermissionRationale(ctx, permission);
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/AddNearbyContactViewModel.java

@@ -0,0 +1,517 @@
+package org.briarproject.briar.android.contact.add.nearby;
+
+import android.app.Application;
+import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.graphics.Bitmap;
+import android.util.DisplayMetrics;
+import android.widget.Toast;
+
+import com.google.zxing.Result;
+
+import org.briarproject.bramble.api.UnsupportedVersionException;
+import org.briarproject.bramble.api.connection.ConnectionManager;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactExchangeManager;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.ContactExistsException;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
+import org.briarproject.bramble.api.keyagreement.Payload;
+import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
+import org.briarproject.bramble.api.keyagreement.PayloadParser;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementAbortedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFailedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStartedEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.BluetoothConstants;
+import org.briarproject.bramble.api.plugin.LanTcpConstants;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.Plugin.State;
+import org.briarproject.bramble.api.plugin.PluginManager;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeFinished;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult.Error;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeResult.Success;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.ContactExchangeStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementListening;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementStarted;
+import org.briarproject.briar.android.contact.add.nearby.AddContactState.KeyAgreementWaiting;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+import javax.inject.Provider;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
+import static android.widget.Toast.LENGTH_LONG;
+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.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.areEssentialPermissionsGranted;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactPermissionManager.isLocationEnabled;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.NO_ADAPTER;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.REFUSED;
+import static org.briarproject.briar.android.contact.add.nearby.AddNearbyContactViewModel.BluetoothDecision.UNKNOWN;
+
+@NotNullByDefault
+class AddNearbyContactViewModel extends AndroidViewModel
+		implements EventListener, QrCodeDecoder.ResultCallback {
+
+	private static final Logger LOG =
+			getLogger(AddNearbyContactViewModel.class.getName());
+
+	enum BluetoothDecision {
+		/**
+		 * We haven't asked the user about Bluetooth discoverability.
+		 */
+		UNKNOWN,
+
+		/**
+		 * The device doesn't have a Bluetooth adapter.
+		 */
+		NO_ADAPTER,
+
+		/**
+		 * We're waiting for the user to accept or refuse discoverability.
+		 */
+		WAITING,
+
+		/**
+		 * The user has accepted discoverability.
+		 */
+		ACCEPTED,
+
+		/**
+		 * The user has refused discoverability.
+		 */
+		REFUSED
+	}
+
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
+	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
+
+	private final EventBus eventBus;
+	private final AndroidExecutor androidExecutor;
+	private final Executor ioExecutor;
+	private final PluginManager pluginManager;
+	private final PayloadEncoder payloadEncoder;
+	private final PayloadParser payloadParser;
+	private final Provider<KeyAgreementTask> keyAgreementTaskProvider;
+	private final ContactExchangeManager contactExchangeManager;
+	private final ConnectionManager connectionManager;
+
+	private final MutableLiveEvent<Boolean> requestBluetoothDiscoverable =
+			new MutableLiveEvent<>();
+	private final MutableLiveEvent<Boolean> showQrCodeFragment =
+			new MutableLiveEvent<>();
+	private final MutableLiveData<AddContactState> state =
+			new MutableLiveData<>();
+
+	private final QrCodeDecoder qrCodeDecoder;
+	private final BroadcastReceiver bluetoothReceiver =
+			new BluetoothStateReceiver();
+
+	@Nullable
+	private final BluetoothAdapter bt;
+	@Nullable
+	private final Plugin wifiPlugin, bluetoothPlugin;
+
+	// UiThread
+	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
+
+	private boolean wasContinueClicked = false;
+
+	/**
+	 * Records whether we've enabled the wifi plugin so we don't enable it more
+	 * than once.
+	 */
+	private boolean hasEnabledWifi = false;
+
+	/**
+	 * Records whether we've enabled the Bluetooth plugin so we don't enable it
+	 * more than once.
+	 */
+	private boolean hasEnabledBluetooth = false;
+
+	@Nullable
+	private volatile KeyAgreementTask task;
+	private volatile boolean gotLocalPayload = false, gotRemotePayload = false;
+
+	@Inject
+	AddNearbyContactViewModel(Application app,
+			EventBus eventBus,
+			AndroidExecutor androidExecutor,
+			@IoExecutor Executor ioExecutor,
+			PluginManager pluginManager,
+			PayloadEncoder payloadEncoder,
+			PayloadParser payloadParser,
+			Provider<KeyAgreementTask> keyAgreementTaskProvider,
+			ContactExchangeManager contactExchangeManager,
+			ConnectionManager connectionManager) {
+		super(app);
+		this.eventBus = eventBus;
+		this.androidExecutor = androidExecutor;
+		this.ioExecutor = ioExecutor;
+		this.pluginManager = pluginManager;
+		this.payloadEncoder = payloadEncoder;
+		this.payloadParser = payloadParser;
+		this.keyAgreementTaskProvider = keyAgreementTaskProvider;
+		this.contactExchangeManager = contactExchangeManager;
+		this.connectionManager = connectionManager;
+		bt = BluetoothAdapter.getDefaultAdapter();
+		wifiPlugin = pluginManager.getPlugin(LanTcpConstants.ID);
+		bluetoothPlugin = pluginManager.getPlugin(BluetoothConstants.ID);
+		qrCodeDecoder = new QrCodeDecoder(androidExecutor, ioExecutor, this);
+		eventBus.addListener(this);
+		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
+		getApplication().registerReceiver(bluetoothReceiver, filter);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		getApplication().unregisterReceiver(bluetoothReceiver);
+		eventBus.removeListener(this);
+		stopListening();
+	}
+
+	@UiThread
+	void onContinueClicked() {
+		if (bluetoothDecision == REFUSED) {
+			bluetoothDecision = UNKNOWN; // Ask again
+		}
+		wasContinueClicked = true;
+	}
+
+	@UiThread
+	boolean isBluetoothSupported() {
+		return bt != null && bluetoothPlugin != null;
+	}
+
+	@UiThread
+	private boolean isWifiReady() {
+		if (wifiPlugin == null) return true; // Continue without wifi
+		State state = wifiPlugin.getState();
+		// Wait for plugin to become enabled
+		return state == ACTIVE || state == INACTIVE;
+	}
+
+	@UiThread
+	private boolean isBluetoothReady() {
+		if (bt == null || bluetoothPlugin == null) {
+			// Continue without Bluetooth
+			return true;
+		}
+		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
+				bluetoothDecision == BluetoothDecision.WAITING ||
+				bluetoothDecision == BluetoothDecision.REFUSED) {
+			// Wait for user to accept
+			return false;
+		}
+		if (bt.getScanMode() != SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
+			// Wait for adapter to become discoverable
+			return false;
+		}
+		// Wait for plugin to become active
+		return bluetoothPlugin.getState() == ACTIVE;
+	}
+
+	@UiThread
+	private void enableWifiIfWeShould() {
+		if (hasEnabledWifi) return;
+		if (wifiPlugin == null) return;
+		State state = wifiPlugin.getState();
+		if (state == STARTING_STOPPING || state == DISABLED) {
+			LOG.info("Enabling wifi plugin");
+			hasEnabledWifi = true;
+			pluginManager.setPluginEnabled(LanTcpConstants.ID, true);
+		}
+	}
+
+	@UiThread
+	private void enableBluetoothIfWeShould() {
+		if (bluetoothDecision != BluetoothDecision.ACCEPTED) return;
+		if (hasEnabledBluetooth) return;
+		if (bluetoothPlugin == null || !isBluetoothSupported()) return;
+		State state = bluetoothPlugin.getState();
+		if (state == STARTING_STOPPING || state == DISABLED) {
+			LOG.info("Enabling Bluetooth plugin");
+			hasEnabledBluetooth = true;
+			pluginManager.setPluginEnabled(BluetoothConstants.ID, true);
+		}
+	}
+
+	@UiThread
+	private void startAddingContact() {
+		// If we return to the intro fragment, the continue button needs to be
+		// clicked again before showing the QR code fragment
+		wasContinueClicked = false;
+		// If we return to the intro fragment, ask for Bluetooth
+		// discoverability again before showing the QR code fragment
+		bluetoothDecision = UNKNOWN;
+		// If we return to the intro fragment, we may need to enable wifi and
+		// Bluetooth again
+		hasEnabledWifi = false;
+		hasEnabledBluetooth = false;
+		// reset state, so we don't show an old QR code again
+		state.setValue(null);
+		resetPayloadFlags();
+		// start to listen with a KeyAgreementTask
+		startListening();
+		showQrCodeFragment.setEvent(true);
+	}
+
+	/**
+	 * Call this once Bluetooth and Wi-Fi are ready to be used.
+	 * It is possible to call this more than once over the ViewModel's lifetime.
+	 */
+	@UiThread
+	private void startListening() {
+		KeyAgreementTask oldTask = task;
+		KeyAgreementTask newTask = keyAgreementTaskProvider.get();
+		task = newTask;
+		ioExecutor.execute(() -> {
+			if (oldTask != null) oldTask.stopListening();
+			newTask.listen();
+		});
+	}
+
+	@UiThread
+	void stopListening() {
+		KeyAgreementTask oldTask = task;
+		ioExecutor.execute(() -> {
+			if (oldTask != null) {
+				oldTask.stopListening();
+				task = null;
+			}
+		});
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof TransportStateEvent) {
+			TransportStateEvent t = (TransportStateEvent) e;
+			if (t.getTransportId().equals(BluetoothConstants.ID)) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Bluetooth state changed to " + t.getState());
+				}
+				showQrCodeFragmentIfAllowed();
+			} else if (t.getTransportId().equals(LanTcpConstants.ID)) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Wifi state changed to " + t.getState());
+				}
+				showQrCodeFragmentIfAllowed();
+			}
+		} else if (e instanceof KeyAgreementListeningEvent) {
+			LOG.info("KeyAgreementListeningEvent received");
+			KeyAgreementListeningEvent event = (KeyAgreementListeningEvent) e;
+			onLocalPayloadReceived(event.getLocalPayload());
+		} else if (e instanceof KeyAgreementWaitingEvent) {
+			LOG.info("KeyAgreementWaitingEvent received");
+			state.setValue(new KeyAgreementWaiting());
+		} else if (e instanceof KeyAgreementStartedEvent) {
+			LOG.info("KeyAgreementStartedEvent received");
+			state.setValue(new KeyAgreementStarted());
+		} else if (e instanceof KeyAgreementFinishedEvent) {
+			LOG.info("KeyAgreementFinishedEvent received");
+			KeyAgreementResult result =
+					((KeyAgreementFinishedEvent) e).getResult();
+			startContactExchange(result);
+			state.setValue(new ContactExchangeStarted());
+		} else if (e instanceof KeyAgreementAbortedEvent) {
+			LOG.info("KeyAgreementAbortedEvent received");
+			resetPayloadFlags();
+			state.setValue(new AddContactState.Failed());
+		} else if (e instanceof KeyAgreementFailedEvent) {
+			LOG.info("KeyAgreementFailedEvent received");
+			resetPayloadFlags();
+			state.setValue(new AddContactState.Failed());
+		}
+	}
+
+	@SuppressWarnings("StatementWithEmptyBody")
+	@UiThread
+	void showQrCodeFragmentIfAllowed() {
+		boolean permissionsGranted = areEssentialPermissionsGranted(
+				getApplication(), isBluetoothSupported());
+		boolean locationEnabled = isLocationEnabled(getApplication());
+		if (wasContinueClicked && permissionsGranted && locationEnabled) {
+			if (isWifiReady() && isBluetoothReady()) {
+				LOG.info("Wifi and Bluetooth are ready");
+				startAddingContact();
+			} else {
+				enableWifiIfWeShould();
+				if (bluetoothDecision == UNKNOWN) {
+					if (isBluetoothSupported()) {
+						requestBluetoothDiscoverable.setEvent(true);
+					} else {
+						bluetoothDecision = NO_ADAPTER;
+					}
+				} else if (bluetoothDecision == REFUSED) {
+					// Ask again when the user clicks "continue"
+				} else {
+					enableBluetoothIfWeShould();
+				}
+			}
+		}
+	}
+
+	/**
+	 * This sets the QR code by setting the state to KeyAgreementListening.
+	 */
+	private void onLocalPayloadReceived(Payload localPayload) {
+		if (gotLocalPayload) return;
+		DisplayMetrics dm = getApplication().getResources().getDisplayMetrics();
+		ioExecutor.execute(() -> {
+			byte[] payloadBytes = payloadEncoder.encode(localPayload);
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Local payload is " + payloadBytes.length
+						+ " bytes");
+			}
+			// Use ISO 8859-1 to encode bytes directly as a string
+			String content = new String(payloadBytes, ISO_8859_1);
+			Bitmap qrCode = QrCodeUtils.createQrCode(dm, content);
+			gotLocalPayload = true;
+			state.postValue(new KeyAgreementListening(qrCode));
+		});
+	}
+
+	@Override
+	@IoExecutor
+	public void onQrCodeDecoded(Result result) {
+		LOG.info("Got result from decoder");
+		KeyAgreementTask currentTask = task;
+		// Ignore results until the KeyAgreementTask is ready
+		if (!gotLocalPayload || gotRemotePayload || currentTask == null) return;
+		try {
+			byte[] payloadBytes = result.getText().getBytes(ISO_8859_1);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Remote payload is " + payloadBytes.length + " bytes");
+			Payload remotePayload = payloadParser.parse(payloadBytes);
+			gotRemotePayload = true;
+			currentTask.connectAndRunProtocol(remotePayload);
+			state.postValue(new AddContactState.QrCodeScanned());
+		} catch (UnsupportedVersionException e) {
+			resetPayloadFlags();
+			state.postValue(new AddContactState.Failed(e.isTooOld()));
+		} catch (IOException | IllegalArgumentException e) {
+			LOG.log(WARNING, "QR Code Invalid", e);
+			androidExecutor.runOnUiThread(() -> Toast.makeText(getApplication(),
+					R.string.qr_code_invalid, LENGTH_LONG).show());
+			resetPayloadFlags();
+			state.postValue(new AddContactState.Failed());
+		}
+	}
+
+	private void resetPayloadFlags() {
+		gotRemotePayload = false;
+		gotLocalPayload = false;
+	}
+
+	@UiThread
+	private void startContactExchange(KeyAgreementResult result) {
+		TransportId t = result.getTransportId();
+		DuplexTransportConnection conn = result.getConnection();
+		SecretKey masterKey = result.getMasterKey();
+		boolean alice = result.wasAlice();
+		ioExecutor.execute(() -> {
+			try {
+				Contact contact = contactExchangeManager.exchangeContacts(conn,
+						masterKey, alice, true);
+				// Reuse the connection as a transport connection
+				connectionManager
+						.manageOutgoingConnection(contact.getId(), t, conn);
+				Success success = new Success(contact.getAuthor());
+				state.postValue(new ContactExchangeFinished(success));
+			} catch (ContactExistsException e) {
+				tryToClose(conn);
+				Error error = new Error(e.getRemoteAuthor());
+				state.postValue(new ContactExchangeFinished(error));
+			} catch (DbException | IOException e) {
+				tryToClose(conn);
+				logException(LOG, WARNING, e);
+				Error error = new Error(null);
+				state.postValue(new ContactExchangeFinished(error));
+			}
+		});
+	}
+
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+		@UiThread
+		@Override
+		public void onReceive(Context context, Intent intent) {
+			int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, -1);
+			LOG.info("Bluetooth scan mode changed: " + scanMode);
+			showQrCodeFragmentIfAllowed();
+		}
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getReader().dispose(true, true);
+			conn.getWriter().dispose(true);
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	@UiThread
+	void setBluetoothDecision(BluetoothDecision decision) {
+		bluetoothDecision = decision;
+		showQrCodeFragmentIfAllowed();
+	}
+
+	QrCodeDecoder getQrCodeDecoder() {
+		return qrCodeDecoder;
+	}
+
+	LiveEvent<Boolean> getRequestBluetoothDiscoverable() {
+		return requestBluetoothDiscoverable;
+	}
+
+	LiveEvent<Boolean> getShowQrCodeFragment() {
+		return showQrCodeFragment;
+	}
+
+	/**
+	 * This LiveData will be null initially.
+	 */
+	LiveData<AddContactState> getState() {
+		return state;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/CameraException.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import java.io.IOException;
 

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/CameraView.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.content.Context;
 import android.hardware.Camera;
@@ -40,7 +40,6 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
-@SuppressWarnings("deprecation")
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
@@ -126,8 +125,14 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			throw new CameraException(e);
 		}
 		setDisplayOrientation(getScreenRotationDegrees());
+		if (camera == null) throw new CameraException("No camera found");
 		// Use barcode scene mode if it's available
-		Parameters params = camera.getParameters();
+		Parameters params;
+		try {
+			params = camera.getParameters();
+		} catch (RuntimeException e) {
+			throw new CameraException(e);
+		}
 		params = setSceneMode(camera, params);
 		if (SCENE_MODE_BARCODE.equals(params.getSceneMode())) {
 			// If the scene mode enabled the flash, try to disable it

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/PreviewConsumer.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.hardware.Camera;
 
@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import androidx.annotation.UiThread;
 
-@SuppressWarnings("deprecation")
 @NotNullByDefault
 interface PreviewConsumer {
 

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/QrCodeDecoder.java

@@ -1,10 +1,9 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.hardware.Camera;
 import android.hardware.Camera.CameraInfo;
 import android.hardware.Camera.PreviewCallback;
 import android.hardware.Camera.Size;
-import android.os.AsyncTask;
 
 import com.google.zxing.BinaryBitmap;
 import com.google.zxing.LuminanceSource;
@@ -15,10 +14,13 @@ import com.google.zxing.Result;
 import com.google.zxing.common.HybridBinarizer;
 import com.google.zxing.qrcode.QRCodeReader;
 
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 
+import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import androidx.annotation.UiThread;
@@ -26,22 +28,26 @@ import androidx.annotation.UiThread;
 import static com.google.zxing.DecodeHintType.CHARACTER_SET;
 import static java.util.Collections.singletonMap;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 
-@SuppressWarnings("deprecation")
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
-	private static final Logger LOG =
+	private static final Logger LOG = getLogger(QrCodeDecoder.class.getName());
-			Logger.getLogger(QrCodeDecoder.class.getName());
 
+	private final AndroidExecutor androidExecutor;
+	private final Executor ioExecutor;
 	private final Reader reader = new QRCodeReader();
 	private final ResultCallback callback;
 
 	private Camera camera = null;
 	private int cameraIndex = 0;
 
-	QrCodeDecoder(ResultCallback callback) {
+	QrCodeDecoder(AndroidExecutor androidExecutor,
+			@IoExecutor Executor ioExecutor, ResultCallback callback) {
+		this.androidExecutor = androidExecutor;
+		this.ioExecutor = ioExecutor;
 		this.callback = callback;
 	}
 
@@ -74,8 +80,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 				if (data.length == size.width * size.height * 3 / 2) {
 					CameraInfo info = new CameraInfo();
 					Camera.getCameraInfo(cameraIndex, info);
-					new DecoderTask(data, size.width, size.height,
+					decode(data, size.width, size.height, info.orientation);
-							info.orientation).execute();
 				} else {
 					// Camera parameters have changed - ask for a new preview
 					LOG.info("Preview size does not match camera parameters");
@@ -89,43 +94,23 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 		}
 	}
 
-	private class DecoderTask extends AsyncTask<Void, Void, Void> {
+	private void decode(byte[] data, int width, int height, int orientation) {
-
+		ioExecutor.execute(() -> {
-		private final byte[] data;
-		private final int width, height, orientation;
-
-		private DecoderTask(byte[] data, int width, int height,
-				int orientation) {
-			this.data = data;
-			this.width = width;
-			this.height = height;
-			this.orientation = orientation;
-		}
-
-		@Override
-		protected Void doInBackground(Void... params) {
 			BinaryBitmap bitmap = binarize(data, width, height, orientation);
 			Result result;
 			try {
 				result = reader.decode(bitmap,
 						singletonMap(CHARACTER_SET, "ISO8859_1"));
+				callback.onQrCodeDecoded(result);
 			} catch (ReaderException e) {
 				// No barcode found
-				return null;
 			} catch (RuntimeException e) {
 				LOG.warning("Invalid preview frame");
-				return null;
 			} finally {
 				reader.reset();
+				androidExecutor.runOnUiThread(this::askForPreviewFrame);
 			}
-			callback.handleResult(result);
+		});
-			return null;
-		}
-
-		@Override
-		protected void onPostExecute(Void result) {
-			askForPreviewFrame();
-		}
 	}
 
 	private static BinaryBitmap binarize(byte[] data, int width, int height,
@@ -143,7 +128,7 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
 	@NotNullByDefault
 	interface ResultCallback {
-
+		@IoExecutor
-		void handleResult(Result result);
+		void onQrCodeDecoded(Result result);
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/contact/add/nearby/QrCodeUtils.java

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.keyagreement;
+package org.briarproject.briar.android.contact.add.nearby;
 
 import android.graphics.Bitmap;
 import android.util.DisplayMetrics;
@@ -18,13 +18,13 @@ import static android.graphics.Color.BLACK;
 import static android.graphics.Color.WHITE;
 import static com.google.zxing.BarcodeFormat.QR_CODE;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 class QrCodeUtils {
 
-	private static final Logger LOG =
+	private static final Logger LOG = getLogger(QrCodeUtils.class.getName());
-			Logger.getLogger(QrCodeUtils.class.getName());
 
 	@Nullable
 	static Bitmap createQrCode(DisplayMetrics dm, String input) {

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeActivity.java

@@ -1,119 +0,0 @@
-package org.briarproject.briar.android.keyagreement;
-
-import android.os.Bundle;
-import android.widget.Toast;
-
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
-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 javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.annotation.UiThread;
-import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
-
-import static android.widget.Toast.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class ContactExchangeActivity extends KeyAgreementActivity {
-
-	@Inject
-	ViewModelProvider.Factory viewModelFactory;
-
-	private ContactExchangeViewModel viewModel;
-
-	@Override
-	public void injectActivity(ActivityComponent component) {
-		component.inject(this);
-	}
-
-	@Override
-	public void onCreate(@Nullable Bundle state) {
-		super.onCreate(state);
-		requireNonNull(getSupportActionBar())
-				.setTitle(R.string.add_contact_title);
-		viewModel = ViewModelProviders.of(this, viewModelFactory)
-				.get(ContactExchangeViewModel.class);
-	}
-
-	private void startContactExchange(KeyAgreementResult result) {
-		viewModel.getSucceeded().observe(this, succeeded -> {
-			if (succeeded == null) return;
-			if (succeeded) {
-				Author remote = requireNonNull(viewModel.getRemoteAuthor());
-				contactExchangeSucceeded(remote);
-			} else {
-				Author duplicate = viewModel.getDuplicateAuthor();
-				if (duplicate == null) contactExchangeFailed();
-				else duplicateContact(duplicate);
-			}
-		});
-		viewModel.startContactExchange(result.getTransportId(),
-				result.getConnection(), result.getMasterKey(),
-				result.wasAlice());
-	}
-
-	@UiThread
-	private void contactExchangeSucceeded(Author remoteAuthor) {
-		String contactName = remoteAuthor.getName();
-		String text = getString(R.string.contact_added_toast, contactName);
-		Toast.makeText(this, text, LENGTH_LONG).show();
-		supportFinishAfterTransition();
-	}
-
-	@UiThread
-	private void duplicateContact(Author remoteAuthor) {
-		String contactName = remoteAuthor.getName();
-		String format = getString(R.string.contact_already_exists);
-		String text = String.format(format, contactName);
-		Toast.makeText(this, text, LENGTH_LONG).show();
-		finish();
-	}
-
-	@UiThread
-	private void contactExchangeFailed() {
-		showErrorFragment();
-	}
-
-	@UiThread
-	@Override
-	public void keyAgreementFailed() {
-		showErrorFragment();
-	}
-
-	@UiThread
-	@Override
-	public String keyAgreementWaiting() {
-		return getString(R.string.waiting_for_contact_to_scan);
-	}
-
-	@UiThread
-	@Override
-	public String keyAgreementStarted() {
-		return getString(R.string.authenticating_with_device);
-	}
-
-	@UiThread
-	@Override
-	public void keyAgreementAborted(boolean remoteAborted) {
-		showErrorFragment();
-	}
-
-	@UiThread
-	@Override
-	public String keyAgreementFinished(KeyAgreementResult result) {
-		startContactExchange(result);
-		return getString(R.string.exchanging_contact_details);
-	}
-
-	private void showErrorFragment() {
-		showNextFragment(new ContactExchangeErrorFragment());
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeViewModel.java

@@ -1,105 +0,0 @@
-package org.briarproject.briar.android.keyagreement;
-
-import android.app.Application;
-
-import org.briarproject.bramble.api.connection.ConnectionManager;
-import org.briarproject.bramble.api.contact.Contact;
-import org.briarproject.bramble.api.contact.ContactExchangeManager;
-import org.briarproject.bramble.api.crypto.SecretKey;
-import org.briarproject.bramble.api.db.ContactExistsException;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-
-import java.io.IOException;
-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.AndroidViewModel;
-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.logException;
-
-@NotNullByDefault
-class ContactExchangeViewModel extends AndroidViewModel {
-
-	private static final Logger LOG =
-			getLogger(ContactExchangeViewModel.class.getName());
-
-	private final Executor ioExecutor;
-	private final ContactExchangeManager contactExchangeManager;
-	private final ConnectionManager connectionManager;
-	private final MutableLiveData<Boolean> succeeded = new MutableLiveData<>();
-
-	@Nullable
-	private volatile Author remoteAuthor, duplicateAuthor;
-
-	@Inject
-	ContactExchangeViewModel(Application app, @IoExecutor Executor ioExecutor,
-			ContactExchangeManager contactExchangeManager,
-			ConnectionManager connectionManager) {
-		super(app);
-		this.ioExecutor = ioExecutor;
-		this.contactExchangeManager = contactExchangeManager;
-		this.connectionManager = connectionManager;
-	}
-
-	@UiThread
-	void startContactExchange(TransportId t, DuplexTransportConnection conn,
-			SecretKey masterKey, boolean alice) {
-		ioExecutor.execute(() -> {
-			try {
-				Contact contact = contactExchangeManager.exchangeContacts(conn,
-						masterKey, alice, true);
-				// Reuse the connection as a transport connection
-				connectionManager.manageOutgoingConnection(contact.getId(),
-						t, conn);
-				remoteAuthor = contact.getAuthor();
-				succeeded.postValue(true);
-			} catch (ContactExistsException e) {
-				tryToClose(conn);
-				duplicateAuthor = e.getRemoteAuthor();
-				succeeded.postValue(false);
-			} catch (DbException | IOException e) {
-				tryToClose(conn);
-				logException(LOG, WARNING, e);
-				succeeded.postValue(false);
-			}
-		});
-	}
-
-	private void tryToClose(DuplexTransportConnection conn) {
-		try {
-			conn.getReader().dispose(true, true);
-			conn.getWriter().dispose(true);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
-	@UiThread
-	@Nullable
-	Author getRemoteAuthor() {
-		return remoteAuthor;
-	}
-
-	@UiThread
-	@Nullable
-	Author getDuplicateAuthor() {
-		return duplicateAuthor;
-	}
-
-	LiveData<Boolean> getSucceeded() {
-		return succeeded;
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/IntroFragment.java

@@ -1,72 +0,0 @@
-package org.briarproject.briar.android.keyagreement;
-
-import android.content.Context;
-import android.os.Bundle;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.ScrollView;
-
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.fragment.BaseFragment;
-
-import javax.annotation.Nullable;
-
-import static android.view.View.FOCUS_DOWN;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class IntroFragment extends BaseFragment {
-
-	interface IntroScreenSeenListener {
-		void showNextScreen();
-	}
-
-	public static final String TAG = IntroFragment.class.getName();
-
-	private IntroScreenSeenListener screenSeenListener;
-	private ScrollView scrollView;
-
-	public static IntroFragment newInstance() {
-
-		Bundle args = new Bundle();
-
-		IntroFragment fragment = new IntroFragment();
-		fragment.setArguments(args);
-		return fragment;
-	}
-
-	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
-		screenSeenListener = (IntroScreenSeenListener) context;
-	}
-
-	@Override
-	public String getUniqueTag() {
-		return TAG;
-	}
-
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-
-		View v = inflater.inflate(R.layout.fragment_keyagreement_id, container,
-				false);
-		scrollView = v.findViewById(R.id.scrollView);
-		View button = v.findViewById(R.id.continueButton);
-		button.setOnClickListener(view -> screenSeenListener.showNextScreen());
-		return v;
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		scrollView.post(() -> scrollView.fullScroll(FOCUS_DOWN));
-	}
-
-}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementActivity.java

@@ -1,484 +0,0 @@
-package org.briarproject.briar.android.keyagreement;
-
-import android.bluetooth.BluetoothAdapter;
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-import android.os.Bundle;
-import android.view.MenuItem;
-
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.BluetoothConstants;
-import org.briarproject.bramble.api.plugin.LanTcpConstants;
-import org.briarproject.bramble.api.plugin.Plugin;
-import org.briarproject.bramble.api.plugin.Plugin.State;
-import org.briarproject.bramble.api.plugin.PluginManager;
-import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
-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;
-import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
-import org.briarproject.briar.android.keyagreement.IntroFragment.IntroScreenSeenListener;
-import org.briarproject.briar.android.keyagreement.KeyAgreementFragment.KeyAgreementEventListener;
-
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-
-import androidx.annotation.StringRes;
-import androidx.annotation.UiThread;
-import androidx.appcompat.app.AlertDialog.Builder;
-import androidx.appcompat.widget.Toolbar;
-import androidx.core.app.ActivityCompat;
-import androidx.fragment.app.FragmentManager;
-
-import static android.Manifest.permission.ACCESS_FINE_LOCATION;
-import static android.Manifest.permission.CAMERA;
-import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
-import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
-import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
-import static android.content.pm.PackageManager.PERMISSION_GRANTED;
-import static android.os.Build.VERSION.SDK_INT;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
-import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_BLUETOOTH_DISCOVERABLE;
-import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA_LOCATION;
-import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public abstract class KeyAgreementActivity extends BriarActivity implements
-		BaseFragmentListener, IntroScreenSeenListener,
-		KeyAgreementEventListener, EventListener {
-
-	private enum BluetoothDecision {
-		/**
-		 * We haven't asked the user about Bluetooth discoverability.
-		 */
-		UNKNOWN,
-
-		/**
-		 * The device doesn't have a Bluetooth adapter.
-		 */
-		NO_ADAPTER,
-
-		/**
-		 * We're waiting for the user to accept or refuse discoverability.
-		 */
-		WAITING,
-
-		/**
-		 * The user has accepted discoverability.
-		 */
-		ACCEPTED,
-
-		/**
-		 * The user has refused discoverability.
-		 */
-		REFUSED
-	}
-
-	private enum Permission {
-		UNKNOWN, GRANTED, SHOW_RATIONALE, PERMANENTLY_DENIED
-	}
-
-	private static final Logger LOG =
-			getLogger(KeyAgreementActivity.class.getName());
-
-	@Inject
-	EventBus eventBus;
-
-	@Inject
-	PluginManager pluginManager;
-
-	/**
-	 * Set to true in onPostResume() and false in onPause(). This prevents the
-	 * QR code fragment from being shown if onRequestPermissionsResult() is
-	 * called while the activity is paused, which could cause a crash due to
-	 * https://issuetracker.google.com/issues/37067655.
-	 */
-	private boolean isResumed = false;
-
-	/**
-	 * Set to true when the continue button is clicked, and false when the QR
-	 * code fragment is shown. This prevents the QR code fragment from being
-	 * shown automatically before the continue button has been clicked.
-	 */
-	private boolean continueClicked = false;
-
-	/**
-	 * Records whether we've enabled the wifi plugin so we don't enable it more
-	 * than once.
-	 */
-	private boolean hasEnabledWifi = false;
-
-	/**
-	 * Records whether we've enabled the Bluetooth plugin so we don't enable it
-	 * more than once.
-	 */
-	private boolean hasEnabledBluetooth = false;
-
-	private Permission cameraPermission = Permission.UNKNOWN;
-	private Permission locationPermission = Permission.UNKNOWN;
-	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
-	private BroadcastReceiver bluetoothReceiver = null;
-	private Plugin wifiPlugin = null, bluetoothPlugin = null;
-	private BluetoothAdapter bt = null;
-
-	@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_toolbar);
-		Toolbar toolbar = findViewById(R.id.toolbar);
-		setSupportActionBar(toolbar);
-		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
-		if (state == null) {
-			showInitialFragment(IntroFragment.newInstance());
-		}
-		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
-		bluetoothReceiver = new BluetoothStateReceiver();
-		registerReceiver(bluetoothReceiver, filter);
-		wifiPlugin = pluginManager.getPlugin(LanTcpConstants.ID);
-		bluetoothPlugin = pluginManager.getPlugin(BluetoothConstants.ID);
-		bt = BluetoothAdapter.getDefaultAdapter();
-	}
-
-	@Override
-	public void onDestroy() {
-		super.onDestroy();
-		if (bluetoothReceiver != null) unregisterReceiver(bluetoothReceiver);
-	}
-
-	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == android.R.id.home) {
-			onBackPressed();
-			return true;
-		}
-		return super.onOptionsItemSelected(item);
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		eventBus.addListener(this);
-		// Permissions may have been granted manually while we were stopped
-		cameraPermission = Permission.UNKNOWN;
-		locationPermission = Permission.UNKNOWN;
-	}
-
-	@Override
-	protected void onPostResume() {
-		super.onPostResume();
-		isResumed = true;
-		// Workaround for
-		// https://code.google.com/p/android/issues/detail?id=190966
-		showQrCodeFragmentIfAllowed();
-	}
-
-	@SuppressWarnings("StatementWithEmptyBody")
-	private void showQrCodeFragmentIfAllowed() {
-		if (isResumed && continueClicked && areEssentialPermissionsGranted()) {
-			if (isWifiReady() && isBluetoothReady()) {
-				LOG.info("Wifi and Bluetooth are ready");
-				showQrCodeFragment();
-			} else {
-				if (shouldEnableWifi()) {
-					LOG.info("Enabling wifi plugin");
-					hasEnabledWifi = true;
-					pluginManager.setPluginEnabled(LanTcpConstants.ID, true);
-				}
-				if (bluetoothDecision == BluetoothDecision.UNKNOWN) {
-					requestBluetoothDiscoverable();
-				} else if (bluetoothDecision == BluetoothDecision.REFUSED) {
-					// Ask again when the user clicks "continue"
-				} else if (shouldEnableBluetooth()) {
-					LOG.info("Enabling Bluetooth plugin");
-					hasEnabledBluetooth = true;
-					pluginManager.setPluginEnabled(BluetoothConstants.ID, true);
-				}
-			}
-		}
-	}
-
-	private boolean areEssentialPermissionsGranted() {
-		return cameraPermission == Permission.GRANTED &&
-				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
-						!isBluetoothSupported());
-	}
-
-	private boolean isBluetoothSupported() {
-		return bt != null && bluetoothPlugin != null;
-	}
-
-	private boolean isWifiReady() {
-		if (wifiPlugin == null) return true; // Continue without wifi
-		State state = wifiPlugin.getState();
-		// Wait for plugin to become enabled
-		return state == ACTIVE || state == INACTIVE;
-	}
-
-	private boolean isBluetoothReady() {
-		if (!isBluetoothSupported()) {
-			// Continue without Bluetooth
-			return true;
-		}
-		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
-				bluetoothDecision == BluetoothDecision.WAITING ||
-				bluetoothDecision == BluetoothDecision.REFUSED) {
-			// Wait for user to accept
-			return false;
-		}
-		if (bt.getScanMode() != SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
-			// Wait for adapter to become discoverable
-			return false;
-		}
-		// Wait for plugin to become active
-		return bluetoothPlugin.getState() == ACTIVE;
-	}
-
-	private boolean shouldEnableWifi() {
-		if (hasEnabledWifi) return false;
-		if (wifiPlugin == null) return false;
-		State state = wifiPlugin.getState();
-		return state == STARTING_STOPPING || state == DISABLED;
-	}
-
-	private void requestBluetoothDiscoverable() {
-		if (!isBluetoothSupported()) {
-			bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-			showQrCodeFragmentIfAllowed();
-		} else {
-			Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
-			if (i.resolveActivity(getPackageManager()) != null) {
-				LOG.info("Asking for Bluetooth discoverability");
-				bluetoothDecision = BluetoothDecision.WAITING;
-				startActivityForResult(i, REQUEST_BLUETOOTH_DISCOVERABLE);
-			} else {
-				bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-				showQrCodeFragmentIfAllowed();
-			}
-		}
-	}
-
-	private boolean shouldEnableBluetooth() {
-		if (bluetoothDecision != BluetoothDecision.ACCEPTED) return false;
-		if (hasEnabledBluetooth) return false;
-		if (!isBluetoothSupported()) return false;
-		State state = bluetoothPlugin.getState();
-		return state == STARTING_STOPPING || state == DISABLED;
-	}
-
-	@Override
-	protected void onPause() {
-		super.onPause();
-		isResumed = false;
-	}
-
-	@Override
-	protected void onStop() {
-		super.onStop();
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	public void showNextScreen() {
-		continueClicked = true;
-		if (bluetoothDecision == BluetoothDecision.REFUSED) {
-			bluetoothDecision = BluetoothDecision.UNKNOWN; // Ask again
-		}
-		if (checkPermissions()) showQrCodeFragmentIfAllowed();
-	}
-
-	@Override
-	public void onActivityResult(int request, int result,
-			@Nullable Intent data) {
-		if (request == REQUEST_BLUETOOTH_DISCOVERABLE) {
-			if (result == RESULT_CANCELED) {
-				LOG.info("Bluetooth discoverability was refused");
-				bluetoothDecision = BluetoothDecision.REFUSED;
-			} else {
-				LOG.info("Bluetooth discoverability was accepted");
-				bluetoothDecision = BluetoothDecision.ACCEPTED;
-			}
-			showQrCodeFragmentIfAllowed();
-		} else super.onActivityResult(request, result, data);
-	}
-
-	private void showQrCodeFragment() {
-		// If we return to the intro fragment, the continue button needs to be
-		// clicked again before showing the QR code fragment
-		continueClicked = false;
-		// If we return to the intro fragment, ask for Bluetooth
-		// discoverability again before showing the QR code fragment
-		bluetoothDecision = BluetoothDecision.UNKNOWN;
-		// If we return to the intro fragment, we may need to enable wifi and
-		// Bluetooth again
-		hasEnabledWifi = false;
-		hasEnabledBluetooth = false;
-
-		// FIXME #824
-		FragmentManager fm = getSupportFragmentManager();
-		if (fm.findFragmentByTag(KeyAgreementFragment.TAG) == null) {
-			BaseFragment f = KeyAgreementFragment.newInstance();
-			fm.beginTransaction()
-					.replace(R.id.fragmentContainer, f, f.getUniqueTag())
-					.addToBackStack(f.getUniqueTag())
-					.commit();
-		}
-	}
-
-	private boolean checkPermissions() {
-		if (areEssentialPermissionsGranted()) return true;
-		// If an essential permission has been permanently denied, ask the
-		// user to change the setting
-		if (cameraPermission == Permission.PERMANENTLY_DENIED) {
-			showDenialDialog(R.string.permission_camera_title,
-					R.string.permission_camera_denied_body);
-			return false;
-		}
-		if (isBluetoothSupported() &&
-				locationPermission == Permission.PERMANENTLY_DENIED) {
-			showDenialDialog(R.string.permission_location_title,
-					R.string.permission_location_denied_body);
-			return false;
-		}
-		// Should we show the rationale for one or both permissions?
-		if (cameraPermission == Permission.SHOW_RATIONALE &&
-				locationPermission == Permission.SHOW_RATIONALE) {
-			showRationale(R.string.permission_camera_location_title,
-					R.string.permission_camera_location_request_body);
-		} else if (cameraPermission == Permission.SHOW_RATIONALE) {
-			showRationale(R.string.permission_camera_title,
-					R.string.permission_camera_request_body);
-		} else if (locationPermission == Permission.SHOW_RATIONALE) {
-			showRationale(R.string.permission_location_title,
-					R.string.permission_location_request_body);
-		} else {
-			requestPermissions();
-		}
-		return false;
-	}
-
-	private void showDenialDialog(@StringRes int title, @StringRes int body) {
-		Builder builder = new Builder(this, R.style.BriarDialogTheme);
-		builder.setTitle(title);
-		builder.setMessage(body);
-		builder.setPositiveButton(R.string.ok, getGoToSettingsListener(this));
-		builder.setNegativeButton(R.string.cancel,
-				(dialog, which) -> supportFinishAfterTransition());
-		builder.show();
-	}
-
-	private void showRationale(@StringRes int title, @StringRes int body) {
-		Builder builder = new Builder(this, R.style.BriarDialogTheme);
-		builder.setTitle(title);
-		builder.setMessage(body);
-		builder.setNeutralButton(R.string.continue_button,
-				(dialog, which) -> requestPermissions());
-		builder.show();
-	}
-
-	private void requestPermissions() {
-		String[] permissions;
-		if (isBluetoothSupported()) {
-			permissions = new String[] {CAMERA, ACCESS_FINE_LOCATION};
-		} else {
-			permissions = new String[] {CAMERA};
-		}
-		ActivityCompat.requestPermissions(this, permissions,
-				REQUEST_PERMISSION_CAMERA_LOCATION);
-	}
-
-	@Override
-	@UiThread
-	public void onRequestPermissionsResult(int requestCode,
-			String[] permissions, int[] grantResults) {
-		super.onRequestPermissionsResult(requestCode, permissions,
-				grantResults);
-		if (requestCode != REQUEST_PERMISSION_CAMERA_LOCATION)
-			throw new AssertionError();
-		if (gotPermission(CAMERA, permissions, grantResults)) {
-			cameraPermission = Permission.GRANTED;
-		} else if (shouldShowRationale(CAMERA)) {
-			cameraPermission = Permission.SHOW_RATIONALE;
-		} else {
-			cameraPermission = Permission.PERMANENTLY_DENIED;
-		}
-		if (isBluetoothSupported()) {
-			if (gotPermission(ACCESS_FINE_LOCATION, permissions,
-					grantResults)) {
-				locationPermission = Permission.GRANTED;
-			} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
-				locationPermission = Permission.SHOW_RATIONALE;
-			} else {
-				locationPermission = Permission.PERMANENTLY_DENIED;
-			}
-		}
-		// If a permission dialog has been shown, showing the QR code fragment
-		// on this call path would cause a crash due to
-		// https://code.google.com/p/android/issues/detail?id=190966.
-		// In that case the isResumed flag prevents the fragment from being
-		// shown here, and showQrCodeFragmentIfAllowed() will be called again
-		// from onPostResume().
-		if (checkPermissions()) showQrCodeFragmentIfAllowed();
-	}
-
-	private boolean gotPermission(String permission, String[] permissions,
-			int[] grantResults) {
-		for (int i = 0; i < permissions.length; i++) {
-			if (permission.equals(permissions[i]))
-				return grantResults[i] == PERMISSION_GRANTED;
-		}
-		return false;
-	}
-
-	private boolean shouldShowRationale(String permission) {
-		return ActivityCompat.shouldShowRequestPermissionRationale(this,
-				permission);
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof TransportStateEvent) {
-			TransportStateEvent t = (TransportStateEvent) e;
-			if (t.getTransportId().equals(BluetoothConstants.ID)) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Bluetooth state changed to " + t.getState());
-				}
-				showQrCodeFragmentIfAllowed();
-			} else if (t.getTransportId().equals(LanTcpConstants.ID)) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Wifi state changed to " + t.getState());
-				}
-				showQrCodeFragmentIfAllowed();
-			}
-		}
-	}
-
-	private class BluetoothStateReceiver extends BroadcastReceiver {
-
-		@Override
-		public void onReceive(Context context, Intent intent) {
-			LOG.info("Bluetooth scan mode changed");
-			showQrCodeFragmentIfAllowed();
-		}
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementFragment.java

@@ -1,375 +0,0 @@
-package org.briarproject.briar.android.keyagreement;
-
-import android.content.Context;
-import android.graphics.Bitmap;
-import android.os.Bundle;
-import android.util.DisplayMetrics;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.LinearLayout;
-import android.widget.LinearLayout.LayoutParams;
-import android.widget.TextView;
-import android.widget.Toast;
-
-import com.google.zxing.Result;
-
-import org.briarproject.bramble.api.UnsupportedVersionException;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventBus;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
-import org.briarproject.bramble.api.keyagreement.Payload;
-import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
-import org.briarproject.bramble.api.keyagreement.PayloadParser;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementAbortedEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFailedEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStartedEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.briar.R;
-import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseEventFragment;
-import org.briarproject.briar.android.view.QrCodeView;
-
-import java.io.IOException;
-import java.nio.charset.Charset;
-import java.util.concurrent.Executor;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-import javax.inject.Inject;
-import javax.inject.Provider;
-
-import androidx.annotation.UiThread;
-
-import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
-import static android.view.View.INVISIBLE;
-import static android.view.View.VISIBLE;
-import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
-import static android.widget.LinearLayout.HORIZONTAL;
-import static android.widget.Toast.LENGTH_LONG;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logException;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-public class KeyAgreementFragment extends BaseEventFragment
-		implements QrCodeDecoder.ResultCallback, QrCodeView.FullscreenListener {
-
-	static final String TAG = KeyAgreementFragment.class.getName();
-
-	private static final Logger LOG = Logger.getLogger(TAG);
-	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
-	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
-
-	@Inject
-	Provider<KeyAgreementTask> keyAgreementTaskProvider;
-	@Inject
-	PayloadEncoder payloadEncoder;
-	@Inject
-	PayloadParser payloadParser;
-	@Inject
-	@IoExecutor
-	Executor ioExecutor;
-	@Inject
-	EventBus eventBus;
-
-	private CameraView cameraView;
-	private LinearLayout cameraOverlay;
-	private View statusView;
-	private QrCodeView qrCodeView;
-	private TextView status;
-
-	private boolean gotRemotePayload;
-	private volatile boolean gotLocalPayload;
-	private KeyAgreementTask task;
-	private KeyAgreementEventListener listener;
-
-	public static KeyAgreementFragment newInstance() {
-		Bundle args = new Bundle();
-		KeyAgreementFragment fragment = new KeyAgreementFragment();
-		fragment.setArguments(args);
-		return fragment;
-	}
-
-	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
-		listener = (KeyAgreementEventListener) context;
-	}
-
-	@Override
-	public void injectFragment(ActivityComponent component) {
-		component.inject(this);
-	}
-
-	@Override
-	public String getUniqueTag() {
-		return TAG;
-	}
-
-	@Nullable
-	@Override
-	public View onCreateView(LayoutInflater inflater,
-			@Nullable ViewGroup container,
-			@Nullable Bundle savedInstanceState) {
-		return inflater.inflate(R.layout.fragment_keyagreement_qr, container,
-				false);
-	}
-
-	@Override
-	public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
-		super.onViewCreated(view, savedInstanceState);
-		cameraView = view.findViewById(R.id.camera_view);
-		cameraOverlay = view.findViewById(R.id.camera_overlay);
-		statusView = view.findViewById(R.id.status_container);
-		status = view.findViewById(R.id.connect_status);
-		qrCodeView = view.findViewById(R.id.qr_code_view);
-		qrCodeView.setFullscreenListener(this);
-	}
-
-	@Override
-	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
-		super.onActivityCreated(savedInstanceState);
-		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
-		cameraView.setPreviewConsumer(new QrCodeDecoder(this));
-	}
-
-	@Override
-	public void onStart() {
-		super.onStart();
-		try {
-			cameraView.start();
-		} catch (CameraException e) {
-			logCameraExceptionAndFinish(e);
-		}
-		startListening();
-	}
-
-	@Override
-	public void setFullscreen(boolean fullscreen) {
-		LinearLayout.LayoutParams statusParams, qrCodeParams;
-		if (fullscreen) {
-			// Grow the QR code view to fill its parent
-			statusParams = new LayoutParams(0, 0, 0f);
-			qrCodeParams = new LayoutParams(MATCH_PARENT, MATCH_PARENT, 1f);
-		} else {
-			// Shrink the QR code view to fill half its parent
-			if (cameraOverlay.getOrientation() == HORIZONTAL) {
-				statusParams = new LayoutParams(0, MATCH_PARENT, 1f);
-				qrCodeParams = new LayoutParams(0, MATCH_PARENT, 1f);
-			} else {
-				statusParams = new LayoutParams(MATCH_PARENT, 0, 1f);
-				qrCodeParams = new LayoutParams(MATCH_PARENT, 0, 1f);
-			}
-		}
-		statusView.setLayoutParams(statusParams);
-		qrCodeView.setLayoutParams(qrCodeParams);
-		cameraOverlay.invalidate();
-	}
-
-	@Override
-	public void onStop() {
-		super.onStop();
-		stopListening();
-		try {
-			cameraView.stop();
-		} catch (CameraException e) {
-			logCameraExceptionAndFinish(e);
-		}
-	}
-
-	@UiThread
-	private void logCameraExceptionAndFinish(CameraException e) {
-		logException(LOG, WARNING, e);
-		Toast.makeText(getActivity(), R.string.camera_error,
-				LENGTH_LONG).show();
-		finish();
-	}
-
-	@UiThread
-	private void startListening() {
-		KeyAgreementTask oldTask = task;
-		KeyAgreementTask newTask = keyAgreementTaskProvider.get();
-		task = newTask;
-		ioExecutor.execute(() -> {
-			if (oldTask != null) oldTask.stopListening();
-			newTask.listen();
-		});
-	}
-
-	@UiThread
-	private void stopListening() {
-		KeyAgreementTask oldTask = task;
-		ioExecutor.execute(() -> {
-			if (oldTask != null) oldTask.stopListening();
-		});
-	}
-
-	@UiThread
-	private void reset() {
-		// If we've stopped the camera view, restart it
-		if (gotRemotePayload) {
-			try {
-				cameraView.start();
-			} catch (CameraException e) {
-				logCameraExceptionAndFinish(e);
-				return;
-			}
-		}
-		statusView.setVisibility(INVISIBLE);
-		cameraView.setVisibility(VISIBLE);
-		gotRemotePayload = false;
-		gotLocalPayload = false;
-		startListening();
-	}
-
-	@UiThread
-	private void qrCodeScanned(String content) {
-		try {
-			byte[] payloadBytes = content.getBytes(ISO_8859_1);
-			if (LOG.isLoggable(INFO))
-				LOG.info("Remote payload is " + payloadBytes.length + " bytes");
-			Payload remotePayload = payloadParser.parse(payloadBytes);
-			gotRemotePayload = true;
-			cameraView.stop();
-			cameraView.setVisibility(INVISIBLE);
-			statusView.setVisibility(VISIBLE);
-			status.setText(R.string.connecting_to_device);
-			task.connectAndRunProtocol(remotePayload);
-		} catch (UnsupportedVersionException e) {
-			reset();
-			String msg;
-			if (e.isTooOld()) {
-				msg = getString(R.string.qr_code_too_old,
-						getString(R.string.app_name));
-			} else {
-				msg = getString(R.string.qr_code_too_new,
-						getString(R.string.app_name));
-			}
-			showNextFragment(ContactExchangeErrorFragment.newInstance(msg));
-		} catch (CameraException e) {
-			logCameraExceptionAndFinish(e);
-		} catch (IOException | IllegalArgumentException e) {
-			LOG.log(WARNING, "QR Code Invalid", e);
-			reset();
-			Toast.makeText(getActivity(), R.string.qr_code_invalid,
-					LENGTH_LONG).show();
-		}
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof KeyAgreementListeningEvent) {
-			KeyAgreementListeningEvent event = (KeyAgreementListeningEvent) e;
-			gotLocalPayload = true;
-			setQrCode(event.getLocalPayload());
-		} else if (e instanceof KeyAgreementFailedEvent) {
-			keyAgreementFailed();
-		} else if (e instanceof KeyAgreementWaitingEvent) {
-			keyAgreementWaiting();
-		} else if (e instanceof KeyAgreementStartedEvent) {
-			keyAgreementStarted();
-		} else if (e instanceof KeyAgreementAbortedEvent) {
-			KeyAgreementAbortedEvent event = (KeyAgreementAbortedEvent) e;
-			keyAgreementAborted(event.didRemoteAbort());
-		} else if (e instanceof KeyAgreementFinishedEvent) {
-			keyAgreementFinished(((KeyAgreementFinishedEvent) e).getResult());
-		}
-	}
-
-	@UiThread
-	private void keyAgreementFailed() {
-		reset();
-		listener.keyAgreementFailed();
-	}
-
-	@UiThread
-	private void keyAgreementWaiting() {
-		status.setText(listener.keyAgreementWaiting());
-	}
-
-	@UiThread
-	private void keyAgreementStarted() {
-		qrCodeView.setVisibility(INVISIBLE);
-		statusView.setVisibility(VISIBLE);
-		status.setText(listener.keyAgreementStarted());
-	}
-
-	@UiThread
-	private void keyAgreementAborted(boolean remoteAborted) {
-		reset();
-		listener.keyAgreementAborted(remoteAborted);
-	}
-
-	@UiThread
-	private void keyAgreementFinished(KeyAgreementResult result) {
-		statusView.setVisibility(VISIBLE);
-		status.setText(listener.keyAgreementFinished(result));
-	}
-
-	private void setQrCode(Payload localPayload) {
-		Context context = getContext();
-		if (context == null) return;
-		DisplayMetrics dm = context.getResources().getDisplayMetrics();
-		ioExecutor.execute(() -> {
-			byte[] payloadBytes = payloadEncoder.encode(localPayload);
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Local payload is " + payloadBytes.length
-						+ " bytes");
-			}
-			// Use ISO 8859-1 to encode bytes directly as a string
-			String content = new String(payloadBytes, ISO_8859_1);
-			Bitmap qrCode = QrCodeUtils.createQrCode(dm, content);
-			runOnUiThreadUnlessDestroyed(() -> qrCodeView.setQrCode(qrCode));
-		});
-	}
-
-	@Override
-	public void handleResult(Result result) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			LOG.info("Got result from decoder");
-			// Ignore results until the KeyAgreementTask is ready
-			if (!gotLocalPayload) return;
-			if (!gotRemotePayload) qrCodeScanned(result.getText());
-		});
-	}
-
-	@Override
-	protected void finish() {
-		getActivity().getSupportFragmentManager().popBackStack();
-	}
-
-	@NotNullByDefault
-	interface KeyAgreementEventListener {
-
-		@UiThread
-		void keyAgreementFailed();
-
-		// Should return a string to be displayed as status.
-		@UiThread
-		@Nullable
-		String keyAgreementWaiting();
-
-		// Should return a string to be displayed as status.
-		@UiThread
-		@Nullable
-		String keyAgreementStarted();
-
-		// Will show an error fragment.
-		@UiThread
-		void keyAgreementAborted(boolean remoteAborted);
-
-		// Should return a string to be displayed as status.
-		@UiThread
-		@Nullable
-		String keyAgreementFinished(KeyAgreementResult result);
-	}
-}

briar-android/src/main/java/org/briarproject/briar/android/util/RequestBluetoothDiscoverable.java

@@ -0,0 +1,31 @@
+package org.briarproject.briar.android.util;
+
+
+import android.content.Context;
+import android.content.Intent;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import androidx.activity.result.contract.ActivityResultContract;
+import androidx.annotation.Nullable;
+
+import static android.app.Activity.RESULT_CANCELED;
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
+import static android.bluetooth.BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION;
+
+@NotNullByDefault
+public class RequestBluetoothDiscoverable
+		extends ActivityResultContract<Integer, Boolean> {
+
+	@Override
+	public Intent createIntent(Context context, Integer duration) {
+		Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+		i.putExtra(EXTRA_DISCOVERABLE_DURATION, duration);
+		return i;
+	}
+
+	@Override
+	public Boolean parseResult(int resultCode, @Nullable Intent intent) {
+		return resultCode != RESULT_CANCELED;
+	}
+}

briar-android/src/main/res/layout/activity_fragment_container_toolbar.xml

@@ -4,11 +4,11 @@
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
 	android:orientation="vertical"
-	tools:context=".android.keyagreement.KeyAgreementActivity">
+	tools:context=".android.contact.add.nearby.AddNearbyContactActivity">
 
 	<include layout="@layout/toolbar" />
 
-	<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+	<FrameLayout
 		android:id="@+id/fragmentContainer"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent" />

briar-android/src/main/res/layout/fragment_keyagreement_qr.xml

@@ -5,7 +5,7 @@
 	android:layout_height="match_parent"
 	android:keepScreenOn="true">
 
-	<org.briarproject.briar.android.keyagreement.CameraView
+	<org.briarproject.briar.android.contact.add.nearby.CameraView
 		android:id="@+id/camera_view"
 		android:layout_width="match_parent"
 		android:layout_height="match_parent" />

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

@@ -609,6 +609,9 @@
 	<string name="permission_camera_location_request_body">To scan the QR code, Briar needs access to the camera.\n\nTo discover Bluetooth devices, Briar needs permission to access your location.\n\nBriar does not store your location or share it with anyone.</string>
 	<string name="permission_camera_denied_body">You have denied access to the camera, but adding contacts requires using the camera.\n\nPlease consider granting access.</string>
 	<string name="permission_location_denied_body">You have denied access to your location, but Briar needs this permission to discover Bluetooth devices.\n\nPlease consider granting access.</string>
+	<string name="permission_location_setting_title">Location setting</string>
+	<string name="permission_location_setting_body">Your device\'s location setting must be turned on to find other devices via Bluetooth. Please enable location to continue. You can disable it again afterwards.</string>
+	<string name="permission_location_setting_button">Enable location</string>
 	<string name="qr_code">QR code</string>
 	<string name="show_qr_code_fullscreen">Show QR code fullscreen</string>