Show that using rules is a pro feature

app/src/main/java/eu/faircode/email/FragmentRule.java

@@ -25,6 +25,7 @@ import android.app.Dialog;
 import android.app.TimePickerDialog;
 import android.content.Context;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.database.Cursor;
 import android.graphics.Color;
 import android.media.RingtoneManager;
@@ -64,6 +65,7 @@ import androidx.constraintlayout.widget.ConstraintLayout;
 import androidx.constraintlayout.widget.Group;
 import androidx.fragment.app.DialogFragment;
 import androidx.lifecycle.Lifecycle;
+import androidx.preference.PreferenceManager;
 
 import com.google.android.material.bottomnavigation.BottomNavigationView;
 import com.google.android.material.snackbar.Snackbar;
@@ -84,6 +86,7 @@ public class FragmentRule extends FragmentBase {
     private ScrollView scroll;
     private ConstraintLayout content;
 
+    private TextView tvPro;
     private TextView tvFolder;
     private EditText etName;
     private AutoCompleteTextView etGroup;
@@ -300,6 +303,7 @@ public class FragmentRule extends FragmentBase {
         scroll = view.findViewById(R.id.scroll);
         content = view.findViewById(R.id.content);
 
+        tvPro = view.findViewById(R.id.tvPro);
         tvFolder = view.findViewById(R.id.tvFolder);
         etName = view.findViewById(R.id.etName);
         etGroup = view.findViewById(R.id.etGroup);
@@ -429,6 +433,11 @@ public class FragmentRule extends FragmentBase {
         grpUrl = view.findViewById(R.id.grpUrl);
         grpSummarize = view.findViewById(R.id.grpSummarize);
 
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getContext());
+        boolean pro = prefs.getBoolean("pro", false);
+
+        tvPro.setVisibility(pro && !BuildConfig.DEBUG ? View.GONE : View.VISIBLE);
+
         adapterGroup = new ArrayAdapter<>(getContext(), R.layout.spinner_item1_dropdown, android.R.id.text1);
         etGroup.setThreshold(1);
         etGroup.setAdapter(adapterGroup);

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

@@ -30,14 +30,27 @@
                 android:focusable="true"
                 android:focusableInTouchMode="true">
 
+                <TextView
+                    android:id="@+id/tvPro"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:paddingTop="12dp"
+                    android:paddingBottom="12dp"
+                    android:text="@string/title_pro_feature"
+                    android:textAppearance="@style/TextAppearance.AppCompat.Medium"
+                    android:textColor="?attr/colorWarning"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toTopOf="parent" />
+
                 <TextView
                     android:id="@+id/tvTitle"
                     android:layout_width="wrap_content"
                     android:layout_height="wrap_content"
+                    android:layout_marginTop="6dp"
                     android:text="@string/title_rule_title"
                     android:textAppearance="@style/TextAppearance.AppCompat.Small"
                     app:layout_constraintStart_toStartOf="parent"
-                    app:layout_constraintTop_toTopOf="parent" />
+                    app:layout_constraintTop_toBottomOf="@id/tvPro" />
 
                 <TextView
                     android:id="@+id/tvFolder"