Only show servo button for few websites (MozillaReality#632)

app/src/common/shared/org/mozilla/vrbrowser/ui/widgets/NavigationBarWidget.java

@@ -30,6 +30,7 @@
 import org.mozilla.vrbrowser.ui.views.NavigationURLBar;
 import org.mozilla.vrbrowser.ui.views.UIButton;
 import org.mozilla.vrbrowser.ui.views.UITextButton;
+import org.mozilla.vrbrowser.utils.ServoUtils;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -392,7 +393,19 @@ public void showVoiceSearch() {
     }
 
     public void updateServoButton() {
-        if (SettingsStore.getInstance(mAppContext).isServoEnabled()) {
+        // We show the Servo button if:
+        // 1. the current session is using Servo. No matter what, we need the toggle button to go back to Gecko.
+        // 2. Or, if the pref is enabled and the current url is white listed.
+        boolean show = false;
+        GeckoSession currentSession = SessionStore.get().getCurrentSession();
+        if (currentSession != null) {
+            String currentUri = SessionStore.get().getCurrentUri();
+            boolean isPrefEnabled = SettingsStore.getInstance(mAppContext).isServoEnabled();
+            boolean isServoSession = ServoUtils.isInstanceOfServoSession(currentSession);
+            boolean isUrlWhiteListed = ServoUtils.isUrlInServoWhiteList(mAppContext, currentUri);
+            show = isServoSession || (isPrefEnabled && isUrlWhiteListed);
+        }
+        if (show) {
             mServoButton.setVisibility(View.VISIBLE);
         } else {
             mServoButton.setVisibility(View.GONE);
@@ -421,6 +434,7 @@ public void onLocationChange(GeckoSession session, String url) {
             mURLBar.setURL(url);
             mReloadButton.setEnabled(true);
         }
+        updateServoButton();
     }
 
     @Override

app/src/common/shared/org/mozilla/vrbrowser/utils/ServoUtils.java

@@ -6,14 +6,17 @@
 import org.mozilla.geckoview.GeckoSession;
 
 import java.lang.reflect.Constructor;
+import java.lang.reflect.Method;
 
 public class ServoUtils {
-    private static final String CLASSNAME = "org.mozilla.servo.ServoSession";
+    private static final String SESSION_CLASSNAME = "org.mozilla.servo.ServoSession";
+    private static final String WHITELIST_CLASSNAME = "org.mozilla.servo.ServoWhiteList";
     private static final String LOGTAG = "ServoUtils";
+    private static Object mServoWhiteList = null;
 
     public static boolean isServoAvailable() {
         try {
-            Class.forName(CLASSNAME);
+            Class.forName(SESSION_CLASSNAME);
             return true;
         } catch (ClassNotFoundException e) {
             return false;
@@ -22,20 +25,39 @@ public static boolean isServoAvailable() {
 
     public static boolean isInstanceOfServoSession(Object obj) {
         try {
-            return Class.forName(CLASSNAME).isInstance(obj);
+            return Class.forName(SESSION_CLASSNAME).isInstance(obj);
         } catch (ClassNotFoundException e) {
             return false;
         }
     }
 
     public static GeckoSession createServoSession(Context context) {
         try {
-            Class servoClass = Class.forName(CLASSNAME);
-            Constructor<?> constructor = servoClass.getConstructor(Context.class);
+            Class clazz = Class.forName(SESSION_CLASSNAME);
+            Constructor<?> constructor = clazz.getConstructor(Context.class);
             return (GeckoSession) constructor.newInstance(context);
         } catch (Exception e) {
             Log.e(LOGTAG, "Can't load or instanciate ServoSession: " + e);
             return null;
         }
     }
+
+    public static boolean isUrlInServoWhiteList(Context context, String url) {
+        if (isServoAvailable()) {
+            try {
+                Class clazz = Class.forName(WHITELIST_CLASSNAME);
+                if (mServoWhiteList == null) {
+                    Constructor<?> constructor = clazz.getConstructor(Context.class);
+                    mServoWhiteList = constructor.newInstance(context);
+                }
+                Method isAllowed = clazz.getMethod("isAllowed", String.class);
+                return (boolean) isAllowed.invoke(mServoWhiteList, url);
+            } catch (Exception e) {
+                Log.e(LOGTAG, "Failed to call ServoWhiteList::isAllowed: " + e);
+                return false;
+            }
+        } else {
+            return false;
+        }
+    }
 }

servo/src/main/java/org/mozilla/servo/ServoWhiteList.java

@@ -0,0 +1,23 @@
+package org.mozilla.servo;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.util.Log;
+
+import java.util.Arrays;
+import java.util.regex.Pattern;
+import java.util.stream.Stream;
+
+public class ServoWhiteList {
+    private final Pattern[] mRules;
+
+    public ServoWhiteList(Context context) {
+        Resources res = context.getResources();
+        Stream<String> rules = Stream.of(res.getStringArray(R.array.servo_white_list));
+        mRules = rules.map(Pattern::compile).toArray(Pattern[]::new);
+    }
+
+    public boolean isAllowed(String url) {
+        return url != null && Stream.of(mRules).anyMatch(r -> r.matcher(url).matches());
+    }
+}

servo/src/main/res/values/servo_white_list.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="servo_white_list">
+        <!--
+        Matches:
+            https://servo.org
+            https://download.servo.org
+            https://download.servo.org
+            https://servo.org/
+            https://servo.org/ddd
+        Doesn't match:
+            https://.servo.org/ddd
+            https://servo.orgd
+            http://servo.org
+        -->
+        <item>https:\/\/(.+\.)?servo\.org(\/.*)?$</item>
+        <!-- All examples hosted under threejs.org/examples/ -->
+        <item>https:\/\/threejs\.org\/examples\/.*</item>
+    </string-array>
+</resources>