Add error message for invalid links

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

@@ -17,6 +17,7 @@ import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.util.logging.Logger;
+import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
@@ -41,7 +42,10 @@ public class ContactLinkExchangeActivity extends BriarActivity implements
 	private static final Logger LOG =
 			Logger.getLogger(ContactLinkExchangeActivity.class.getName());
 
-	static final String OUR_LINK = "briar://" + getRandomBase32String(128);
+	static final int LINK_LENGTH = 128;
+	static final Pattern LINK_REGEX =
+			Pattern.compile("(briar://)?([a-z2-7]{" + LINK_LENGTH + "})");
+	static final String OUR_LINK = "briar://" + getRandomBase32String(LINK_LENGTH);;
 
 	@Inject
 	LifecycleManager lifecycleManager;
@@ -104,9 +108,8 @@ public class ContactLinkExchangeActivity extends BriarActivity implements
 		}
 	}
 
-	boolean isBriarLink(CharSequence s) {
+	boolean isBriarLink(@Nullable CharSequence s) {
-		String link = s.toString().trim();
+		return s != null && LINK_REGEX.matcher(s).matches();
-		return link.matches("^(briar://)?[a-z2-7]{64}$");
 	}
 
 	void scanCode() {
@@ -132,7 +135,7 @@ public class ContactLinkExchangeActivity extends BriarActivity implements
 
 		AlarmManager alarmManager =
 				(AlarmManager) requireNonNull(getSystemService(ALARM_SERVICE));
-		double random = getPseudoRandom(link, OUR_LINK);
+		double random = getPseudoRandom(link, OUR_LINK.replace("briar://", ""));
 		long m = MINUTES.toMillis(1);
 		long fromNow = (long) (-m * Math.log(random));
 		LOG.info("Delay " + fromNow + " ms based on seed " + random);

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

@@ -6,6 +6,8 @@ import android.content.Intent;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.support.annotation.NonNull;
+import android.support.design.widget.TextInputEditText;
+import android.support.design.widget.TextInputLayout;
 import android.support.v7.app.AlertDialog;
 import android.text.Editable;
 import android.text.TextWatcher;
@@ -13,7 +15,6 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
-import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.Toast;
 
@@ -21,6 +22,8 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 
+import java.util.regex.Matcher;
+
 import javax.annotation.Nullable;
 
 import static android.content.Context.CLIPBOARD_SERVICE;
@@ -31,6 +34,7 @@ import static android.support.v4.graphics.drawable.DrawableCompat.setTint;
 import static android.support.v4.graphics.drawable.DrawableCompat.wrap;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Objects.requireNonNull;
+import static org.briarproject.briar.android.contact.ContactLinkExchangeActivity.LINK_REGEX;
 import static org.briarproject.briar.android.contact.ContactLinkExchangeActivity.OUR_LINK;
 import static org.briarproject.briar.android.util.UiUtils.resolveColorAttribute;
 
@@ -48,8 +52,8 @@ public class ContactLinkExchangeFragment extends BaseFragment
 	}
 
 	private ClipboardManager clipboard;
-	private EditText linkInput;
+	private TextInputLayout linkInputLayout;
-	private EditText contactNameInput;
+	private TextInputEditText linkInput, contactNameInput;
 	private Button addButton;
 
 	@Override
@@ -92,6 +96,7 @@ public class ContactLinkExchangeFragment extends BaseFragment
 			contactNameInput.setCompoundDrawables(drawable, null, null, null);
 		}
 
+		linkInputLayout = v.findViewById(R.id.linkInputLayout);
 		linkInput = v.findViewById(R.id.linkInput);
 		if (SDK_INT < 23) {
 			Drawable drawable = wrap(linkInput.getCompoundDrawables()[0]);
@@ -166,21 +171,38 @@ public class ContactLinkExchangeFragment extends BaseFragment
 	}
 
 	private void updateAddButtonState() {
-		addButton.setEnabled(contactNameInput.getText().length() > 0 &&
+		boolean validContactName = contactNameInput.getText() != null &&
-				isBriarLink(linkInput.getText().toString()));
+				contactNameInput.getText().length() > 0;
+		boolean briarLink = isBriarLink(linkInput.getText());
+		if (briarLink) {
+			linkInputLayout.setErrorEnabled(false);
+		} else {
+			linkInputLayout.setError("Invalid link");
+		}
+		addButton.setEnabled(validContactName && briarLink);
 	}
 
-	private boolean isBriarLink(CharSequence s) {
+	private boolean isBriarLink(@Nullable CharSequence s) {
 		ContactLinkExchangeActivity activity = getCastActivity();
 		return activity != null && activity.isBriarLink(s);
 	}
 
+	@Nullable
+	private String getLink() {
+		Matcher matcher = LINK_REGEX.matcher(linkInput.getText());
+		if (matcher.matches()) // needs to be called before groups become available
+			return matcher.group(2);
+		else
+			return null;
+	}
+
 	private void onAddButtonClicked() {
 		ContactLinkExchangeActivity activity = getCastActivity();
 		if (activity == null) return;
 
-		String linkText = linkInput.getText().toString();
+		String linkText = getLink();
-		if (linkText.equals(OUR_LINK)) {
+		if (linkText == null) throw new AssertionError();
+		if (OUR_LINK.equals("briar://" + linkText)) {
 			new AlertDialog.Builder(activity, R.style.BriarDialogTheme_Neutral)
 					.setMessage(
 							"Add the link you get from your contact, not your own link.")

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

@@ -11,37 +11,55 @@
 		android:layout_height="wrap_content"
 		android:padding="@dimen/margin_large">
 
-		<EditText
+		<android.support.design.widget.TextInputLayout
-			android:id="@+id/contactNameInput"
+			android:id="@+id/contactNameLayout"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
-			android:drawableLeft="@drawable/ic_person"
+			app:errorEnabled="true"
-			android:drawablePadding="8dp"
+			app:hintEnabled="false"
-			android:drawableStart="@drawable/ic_person"
-			android:drawableTint="?attr/colorControlNormal"
-			android:hint="@string/contact_name_hint"
-			android:importantForAutofill="no"
-			android:inputType="text|textCapWords"
 			app:layout_constraintBottom_toTopOf="@+id/addButton"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/pasteButton"/>
+			app:layout_constraintTop_toBottomOf="@+id/pasteButton">
 
-		<EditText
+			<android.support.design.widget.TextInputEditText
-			android:id="@+id/linkInput"
+				android:id="@+id/contactNameInput"
+				android:layout_width="match_parent"
+				android:layout_height="match_parent"
+				android:drawableLeft="@drawable/ic_person"
+				android:drawablePadding="8dp"
+				android:drawableStart="@drawable/ic_person"
+				android:drawableTint="?attr/colorControlNormal"
+				android:hint="@string/contact_name_hint"
+				android:importantForAutofill="no"
+				android:inputType="text|textCapWords"/>
+
+		</android.support.design.widget.TextInputLayout>
+
+		<android.support.design.widget.TextInputLayout
+			android:id="@+id/linkInputLayout"
 			android:layout_width="0dp"
 			android:layout_height="wrap_content"
 			android:layout_marginTop="16dp"
-			android:drawableLeft="@drawable/ic_link"
+			app:errorEnabled="true"
-			android:drawablePadding="8dp"
+			app:hintEnabled="false"
-			android:drawableStart="@drawable/ic_link"
-			android:drawableTint="?attr/colorControlNormal"
-			android:hint="@string/contact_link_hint"
-			android:importantForAutofill="no"
-			android:inputType="textUri"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/copyButton"/>
+			app:layout_constraintTop_toBottomOf="@+id/copyButton">
+
+			<android.support.design.widget.TextInputEditText
+				android:id="@+id/linkInput"
+				android:layout_width="match_parent"
+				android:layout_height="match_parent"
+				android:drawableLeft="@drawable/ic_link"
+				android:drawablePadding="8dp"
+				android:drawableStart="@drawable/ic_link"
+				android:drawableTint="?attr/colorControlNormal"
+				android:hint="@string/contact_link_hint"
+				android:importantForAutofill="no"
+				android:inputType="textUri"/>
+
+		</android.support.design.widget.TextInputLayout>
 
 		<Button
 			android:id="@+id/pasteButton"
@@ -54,10 +72,10 @@
 			android:drawablePadding="8dp"
 			android:drawableStart="@drawable/ic_content_paste"
 			android:text="@string/paste_button"
-			app:layout_constraintBottom_toTopOf="@+id/contactNameInput"
+			app:layout_constraintBottom_toTopOf="@+id/contactNameLayout"
 			app:layout_constraintEnd_toStartOf="@id/scanCodeButton"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/linkInput"/>
+			app:layout_constraintTop_toBottomOf="@+id/linkInputLayout"/>
 
 		<Button
 			android:id="@+id/scanCodeButton"
@@ -116,7 +134,7 @@
 			android:drawablePadding="8dp"
 			android:drawableStart="@drawable/ic_content_copy"
 			android:text="@string/copy_button"
-			app:layout_constraintBottom_toTopOf="@+id/linkInput"
+			app:layout_constraintBottom_toTopOf="@+id/linkInputLayout"
 			app:layout_constraintEnd_toStartOf="@id/shareButton"
 			app:layout_constraintStart_toStartOf="parent"
 			app:layout_constraintTop_toBottomOf="@+id/linkView"/>
@@ -164,7 +182,7 @@
 			app:layout_constraintBottom_toBottomOf="parent"
 			app:layout_constraintEnd_toEndOf="parent"
 			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/contactNameInput"
+			app:layout_constraintTop_toBottomOf="@+id/contactNameLayout"
 			tools:enabled="true"/>
 
 	</android.support.constraint.ConstraintLayout>