Get rid of KeyAgreementEventListener

and communicate via ViewModel

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

@@ -4,17 +4,17 @@ 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.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState;
 
 import javax.annotation.Nullable;
 
-import androidx.annotation.UiThread;
-
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.Objects.requireNonNull;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.ABORTED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.FAILED;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -25,77 +25,39 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 		super.onCreate(state);
 		requireNonNull(getSupportActionBar())
 				.setTitle(R.string.add_contact_title);
+		viewModel.getKeyAgreementState()
+				.observe(this, this::onKeyAgreementStateChanged);
+		viewModel.getContactExchangeResult()
+				.observe(this, this::onContactExchangeResult);
 	}
 
-	private void startContactExchange(KeyAgreementResult agreementResult) {
-		viewModel.getContactExchangeResult().observe(this, result -> {
-			if (result instanceof ContactExchangeResult.Success) {
-				Author remoteAuthor =
-						((ContactExchangeResult.Success) result).remoteAuthor;
-				contactExchangeSucceeded(remoteAuthor);
-			} else if (result instanceof ContactExchangeResult.Error) {
-				Author duplicateAuthor =
-						((ContactExchangeResult.Error) result).duplicateAuthor;
-				if (duplicateAuthor == null) contactExchangeFailed();
-				else duplicateContact(duplicateAuthor);
-			} else throw new AssertionError();
-		});
-		viewModel.startContactExchange(agreementResult.getTransportId(),
-				agreementResult.getConnection(), agreementResult.getMasterKey(),
-				agreementResult.wasAlice());
+	private void onKeyAgreementStateChanged(KeyAgreementState state) {
+		if (state == ABORTED || state == FAILED) {
+			showErrorFragment();
+		}
 	}
 
-	@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 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 showErrorFragment() {

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

@@ -8,6 +8,15 @@ 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.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.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.TransportId;
@@ -29,32 +38,75 @@ 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;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.ABORTED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.FAILED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.FINISHED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.STARTED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.WAITING;
 
 @NotNullByDefault
-class ContactExchangeViewModel extends AndroidViewModel {
+class ContactExchangeViewModel extends AndroidViewModel
+		implements EventListener {
 
 	private static final Logger LOG =
 			getLogger(ContactExchangeViewModel.class.getName());
 
+	enum KeyAgreementState {
+		WAITING, STARTED, FINISHED, ABORTED, FAILED
+	}
+
+	private final EventBus eventBus;
 	private final Executor ioExecutor;
 	private final ContactExchangeManager contactExchangeManager;
 	private final ConnectionManager connectionManager;
+	private final MutableLiveData<KeyAgreementState> keyAgreementState =
+			new MutableLiveData<>();
 	private final MutableLiveData<ContactExchangeResult> exchangeResult =
 			new MutableLiveData<>();
 
 	@Inject
-	ContactExchangeViewModel(Application app, @IoExecutor Executor ioExecutor,
+	ContactExchangeViewModel(Application app,
+			EventBus eventBus,
+			@IoExecutor Executor ioExecutor,
 			ContactExchangeManager contactExchangeManager,
 			ConnectionManager connectionManager) {
 		super(app);
+		this.eventBus = eventBus;
 		this.ioExecutor = ioExecutor;
 		this.contactExchangeManager = contactExchangeManager;
 		this.connectionManager = connectionManager;
 	}
 
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof KeyAgreementWaitingEvent) {
+			keyAgreementState.setValue(WAITING);
+		} else if (e instanceof KeyAgreementStartedEvent) {
+			keyAgreementState.setValue(STARTED);
+		} else if (e instanceof KeyAgreementAbortedEvent) {
+			keyAgreementState.setValue(ABORTED);
+		} else if (e instanceof KeyAgreementFinishedEvent) {
+			keyAgreementState.setValue(FINISHED);
+			KeyAgreementResult result =
+					((KeyAgreementFinishedEvent) e).getResult();
+			startContactExchange(result);
+		} else if (e instanceof KeyAgreementFailedEvent) {
+			keyAgreementState.setValue(FAILED);
+		}
+	}
+
 	@UiThread
-	void startContactExchange(TransportId t, DuplexTransportConnection conn,
-			SecretKey masterKey, boolean alice) {
+	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,
@@ -83,6 +135,10 @@ class ContactExchangeViewModel extends AndroidViewModel {
 		}
 	}
 
+	LiveData<KeyAgreementState> getKeyAgreementState() {
+		return keyAgreementState;
+	}
+
 	LiveData<ContactExchangeResult> getContactExchangeResult() {
 		return exchangeResult;
 	}

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

@@ -23,7 +23,6 @@ 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.IntroFragment.IntroScreenSeenListener;
-import org.briarproject.briar.android.contact.add.nearby.KeyAgreementFragment.KeyAgreementEventListener;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 
@@ -61,8 +60,7 @@ import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListene
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public abstract class KeyAgreementActivity extends BriarActivity implements
-		BaseFragmentListener, IntroScreenSeenListener,
-		KeyAgreementEventListener, EventListener {
+		BaseFragmentListener, IntroScreenSeenListener, EventListener {
 
 	private enum BluetoothDecision {
 		/**

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

@@ -17,23 +17,17 @@ 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.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState;
 import org.briarproject.briar.android.fragment.BaseEventFragment;
 import org.briarproject.briar.android.view.QrCodeView;
 
@@ -47,6 +41,8 @@ import javax.inject.Inject;
 import javax.inject.Provider;
 
 import androidx.annotation.UiThread;
+import androidx.lifecycle.LifecycleOwner;
+import androidx.lifecycle.ViewModelProvider;
 
 import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
 import static android.view.View.INVISIBLE;
@@ -57,6 +53,11 @@ 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;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.ABORTED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.FAILED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.FINISHED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.STARTED;
+import static org.briarproject.briar.android.contact.add.nearby.ContactExchangeViewModel.KeyAgreementState.WAITING;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -69,6 +70,8 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
 	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
+	@Inject
+	ViewModelProvider.Factory viewModelFactory;
 	@Inject
 	Provider<KeyAgreementTask> keyAgreementTaskProvider;
 	@Inject
@@ -81,6 +84,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@Inject
 	EventBus eventBus;
 
+	private ContactExchangeViewModel viewModel;
 	private CameraView cameraView;
 	private LinearLayout cameraOverlay;
 	private View statusView;
@@ -90,7 +94,6 @@ public class KeyAgreementFragment extends BaseEventFragment
 	private boolean gotRemotePayload;
 	private volatile boolean gotLocalPayload;
 	private KeyAgreementTask task;
-	private KeyAgreementEventListener listener;
 
 	public static KeyAgreementFragment newInstance() {
 		Bundle args = new Bundle();
@@ -99,15 +102,11 @@ public class KeyAgreementFragment extends BaseEventFragment
 		return fragment;
 	}
 
-	@Override
-	public void onAttach(Context context) {
-		super.onAttach(context);
-		listener = (KeyAgreementEventListener) context;
-	}
-
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(requireActivity(), viewModelFactory)
+				.get(ContactExchangeViewModel.class);
 	}
 
 	@Override
@@ -133,6 +132,10 @@ public class KeyAgreementFragment extends BaseEventFragment
 		status = view.findViewById(R.id.connect_status);
 		qrCodeView = view.findViewById(R.id.qr_code_view);
 		qrCodeView.setFullscreenListener(this);
+
+		LifecycleOwner lifecycleOwner = getViewLifecycleOwner();
+		viewModel.getKeyAgreementState()
+				.observe(lifecycleOwner, this::onKeyAgreementStateChanged);
 	}
 
 	@Override
@@ -271,48 +274,23 @@ public class KeyAgreementFragment extends BaseEventFragment
 			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 onKeyAgreementStateChanged(KeyAgreementState state) {
+		if (state == WAITING) {
+			status.setText(R.string.waiting_for_contact_to_scan);
+		} else if (state == STARTED) {
+			qrCodeView.setVisibility(INVISIBLE);
+			statusView.setVisibility(VISIBLE);
+			status.setText(R.string.authenticating_with_device);
+		} else if (state == FINISHED) {
+			statusView.setVisibility(VISIBLE);
+			status.setText(R.string.exchanging_contact_details);
+		} else if (state == ABORTED || state == FAILED) {
+			reset();
+		}
 	}
 
 	private void setQrCode(Payload localPayload) {
@@ -328,7 +306,8 @@ public class KeyAgreementFragment extends BaseEventFragment
 			// 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));
+			runOnUiThreadUnlessDestroyed(
+					() -> qrCodeView.setQrCode(qrCode));
 		});
 	}
 
@@ -347,29 +326,4 @@ public class KeyAgreementFragment extends BaseEventFragment
 		requireActivity().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);
-	}
 }