Show a persistent notice when Research disables tracker blocking

app/src/main/java/eu/faircode/netguard/ActivityMain.java

@@ -588,9 +588,7 @@ public void onRefresh() {
         // Handle intent
         checkExtras(getIntent());
 
-        // Warn about disabled blocking if ADB logging is on
-        if (!Util.isPlayStoreInstall() && prefs.getBoolean("log_logcat", false))
-            Toast.makeText(this, R.string.msg_log_logcat, Toast.LENGTH_SHORT).show();
+        updateResearchModeNotice();
     }
 
     @Override
@@ -657,6 +655,7 @@ protected void onResume() {
                     vpnEnabled && Util.isPrivateDnsBlocked(this) ? View.VISIBLE : View.GONE);
         }
         refreshPrivateDnsBypassBanner();
+        updateResearchModeNotice();
 
         super.onResume();
     }
@@ -687,9 +686,22 @@ public void onConfigurationChanged(Configuration newConfig) {
         updateHorizontalPadding(findViewById(R.id.tvLocalNetwork), horizontalPadding);
         updateHorizontalPadding(findViewById(R.id.tvPrivateDns), horizontalPadding);
         updateHorizontalPadding(findViewById(R.id.tvPrivateDnsBypass), horizontalPadding);
+        updateResearchModeNotice();
         updatePrivateDnsBypassBanner();
     }
 
+    private void updateResearchModeNotice() {
+        TextView notice = findViewById(R.id.tvResearchMode);
+        if (notice == null)
+            return;
+        updateHorizontalPadding(notice, Math.max(
+                getResources().getDimensionPixelSize(R.dimen.activity_horizontal_margin),
+                Math.round(16 * getResources().getDisplayMetrics().density)));
+        notice.setVisibility(PreferenceManager.getDefaultSharedPreferences(this)
+                .getBoolean("log_logcat", false) ? View.VISIBLE : View.GONE);
+        notice.setOnClickListener(view -> startActivity(new Intent(this, ActivitySettings.class)));
+    }
+
     private void updatePrivateDnsBypassBanner() {
         TextView tvPrivateDnsBypass = findViewById(R.id.tvPrivateDnsBypass);
         if (tvPrivateDnsBypass == null)
@@ -1001,6 +1013,9 @@ public void onSharedPreferenceChanged(SharedPreferences prefs, String name) {
 
             updatePrivateDnsBypassBanner();
 
+        } else if ("log_logcat".equals(name)) {
+            updateResearchModeNotice();
+
         } else if ("block_dot".equals(name) || "log".equals(name)) {
             refreshPrivateDnsBypassBanner();
 

app/src/main/res/layout/main.xml

@@ -24,6 +24,25 @@
             app:titleTextColor="@android:color/white" />
     </com.google.android.material.appbar.AppBarLayout>
 
+    <TextView
+        android:id="@+id/tvResearchMode"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:minHeight="48dp"
+        android:gravity="center_vertical"
+        android:background="?attr/selectableItemBackground"
+        android:focusable="true"
+        android:drawableStart="@drawable/ic_warning_amber"
+        android:drawablePadding="8dp"
+        android:drawableTint="?attr/colorError"
+        android:padding="8dp"
+        android:paddingStart="16dp"
+        android:paddingEnd="16dp"
+        android:text="@string/msg_research_mode_notice"
+        android:textAppearance="@style/TextSmall"
+        android:textColor="?attr/colorOff"
+        android:visibility="gone" />
+
     <!--
         Outside llApps on purpose: that container is hidden on the Timeline and
         VPN tabs, and Timeline is where the app lands. A prompt to grant a

app/src/main/res/values/strings.xml

@@ -334,7 +334,8 @@
     <string name="msg_wg_identity_renewed">%1$s no longer knew this device, so TrackerControl registered a new one and updated the %1$s profiles on this device.</string>
     <string name="msg_wg_provider_rejected">%1$s refused to set up this device: %2$s</string>
     <string name="msg_wg_recovery_failed">WireGuard stopped responding. TrackerControl is trying to reconnect, and internet access may remain blocked until WireGuard recovers.</string>
-    <string name="summary_log_logcat">Research mode: identified trackers are logged to ADB and SNI extraction is enabled for better hostname detection. Retrieve logs with adb logcat using tag \'TC-Log\'.</string>
+    <string name="summary_log_logcat">Research mode disables tracker blocking. Identified trackers are logged to ADB and SNI extraction is enabled for better hostname detection. Retrieve logs with adb logcat using tag \'TC-Log\'.</string>
+    <string name="msg_research_mode_notice">Research mode is on. Tracker blocking is disabled. Tap to change settings.</string>
 
     <string name="msg_sure">Are you sure?</string>
     <string name="msg_started">Looking for trackers…</string>

app/src/test/java/eu/faircode/netguard/ActivityMainResearchNoticeTest.java

@@ -0,0 +1,69 @@
+package eu.faircode.netguard;
+
+import static org.junit.Assert.*;
+import static org.robolectric.Shadows.shadowOf;
+
+import android.content.SharedPreferences;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.view.View;
+import android.widget.TextView;
+import androidx.preference.PreferenceManager;
+import net.kollnig.missioncontrol.R;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.Robolectric;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+import org.robolectric.annotation.GraphicsMode;
+import java.io.File;
+import java.io.FileOutputStream;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(sdk = 35, qualifiers = "w320dp-h640dp")
+@GraphicsMode(GraphicsMode.Mode.NATIVE)
+public class ActivityMainResearchNoticeTest {
+    @Test
+    public void noticeFollowsResearchPreferenceOutsideTabContentAndOpensSettings() throws Exception {
+        ActivityMain activity = Robolectric.buildActivity(ActivityMain.class).get();
+        activity.setTheme(R.style.AppTheme_NoActionBar);
+        activity.getDelegate().installViewFactory();
+        activity.setContentView(R.layout.main);
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(activity);
+        // SNI alone does not disable tracker blocking or mean Research is on.
+        prefs.edit().putBoolean("log_logcat", false).putBoolean("sni_enabled", true).commit();
+        activity.onSharedPreferenceChanged(prefs, "log_logcat");
+        TextView notice = activity.findViewById(R.id.tvResearchMode);
+        assertEquals(View.GONE, notice.getVisibility());
+
+        // Imported settings can enable Research without SNI. Still warn.
+        prefs.edit().putBoolean("log_logcat", true).putBoolean("sni_enabled", false).commit();
+        activity.onSharedPreferenceChanged(prefs, "log_logcat");
+        activity.findViewById(R.id.llApps).setVisibility(View.GONE);
+        assertEquals(View.VISIBLE, notice.getVisibility());
+        assertSame(activity.findViewById(R.id.tvPrivateDns).getParent(), notice.getParent());
+        assertTrue(notice.getText().toString().contains("Tracker blocking is disabled"));
+        notice.performClick();
+        assertEquals(ActivitySettings.class.getName(),
+                shadowOf(activity).getNextStartedActivity().getComponent().getClassName());
+
+        int width = Math.round(320 * activity.getResources().getDisplayMetrics().density);
+        View root = (View) notice.getParent();
+        root.measure(View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY),
+                View.MeasureSpec.makeMeasureSpec(width * 2, View.MeasureSpec.EXACTLY));
+        root.layout(0, 0, width, width * 2);
+        assertEquals(0, notice.getLayout().getEllipsisCount(notice.getLineCount() - 1));
+        Bitmap bitmap = Bitmap.createBitmap(width, notice.getHeight(), Bitmap.Config.ARGB_8888);
+        bitmap.eraseColor(android.graphics.Color.WHITE);
+        notice.draw(new Canvas(bitmap));
+        File output = new File("build/reports/research-mode-notice.png");
+        output.getParentFile().mkdirs();
+        try (FileOutputStream stream = new FileOutputStream(output)) {
+            bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
+        }
+
+        prefs.edit().putBoolean("log_logcat", false).putBoolean("sni_enabled", true).commit();
+        activity.onSharedPreferenceChanged(prefs, "log_logcat");
+        assertEquals(View.GONE, notice.getVisibility());
+    }
+}