Convert activity package to Kotlin

Signed-off-by: Harsh Shandilya <me@msfjarvis.dev>

14 files changed, 455 insertions, 532 deletions

diff --git a/ui/src/main/java/com/wireguard/android/activity/BaseActivity.java b/ui/src/main/java/com/wireguard/android/activity/BaseActivity.java
deleted file mode 100644
index 704ca766..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/BaseActivity.java
+++ /dev/null
@@ -1,102 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.os.Bundle;
-
-import com.wireguard.android.Application;
-import com.wireguard.android.model.ObservableTunnel;
-import com.wireguard.util.NonNullForAll;
-
-import java.util.Objects;
-
-import androidx.annotation.Nullable;
-import androidx.databinding.CallbackRegistry;
-import androidx.databinding.CallbackRegistry.NotifierCallback;
-
-/**
- * Base class for activities that need to remember the currently-selected tunnel.
- */
-
-@NonNullForAll
-public abstract class BaseActivity extends ThemeChangeAwareActivity {
-    private static final String KEY_SELECTED_TUNNEL = "selected_tunnel";
-
-    private final SelectionChangeRegistry selectionChangeRegistry = new SelectionChangeRegistry();
-    @Nullable private ObservableTunnel selectedTunnel;
-
-    public void addOnSelectedTunnelChangedListener(final OnSelectedTunnelChangedListener listener) {
-        selectionChangeRegistry.add(listener);
-    }
-
-    @Nullable
-    public ObservableTunnel getSelectedTunnel() {
-        return selectedTunnel;
-    }
-
-    @Override
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        // Restore the saved tunnel if there is one; otherwise grab it from the arguments.
-        final String savedTunnelName;
-        if (savedInstanceState != null)
-            savedTunnelName = savedInstanceState.getString(KEY_SELECTED_TUNNEL);
-        else if (getIntent() != null)
-            savedTunnelName = getIntent().getStringExtra(KEY_SELECTED_TUNNEL);
-        else
-            savedTunnelName = null;
-
-        if (savedTunnelName != null)
-            Application.getTunnelManager().getTunnels()
-                    .thenAccept(tunnels -> setSelectedTunnel(tunnels.get(savedTunnelName)));
-
-        // The selected tunnel must be set before the superclass method recreates fragments.
-        super.onCreate(savedInstanceState);
-    }
-
-    @Override
-    protected void onSaveInstanceState(final Bundle outState) {
-        if (selectedTunnel != null)
-            outState.putString(KEY_SELECTED_TUNNEL, selectedTunnel.getName());
-        super.onSaveInstanceState(outState);
-    }
-
-    protected abstract void onSelectedTunnelChanged(@Nullable ObservableTunnel oldTunnel, @Nullable ObservableTunnel newTunnel);
-
-    public void removeOnSelectedTunnelChangedListener(
-            final OnSelectedTunnelChangedListener listener) {
-        selectionChangeRegistry.remove(listener);
-    }
-
-    public void setSelectedTunnel(@Nullable final ObservableTunnel tunnel) {
-        final ObservableTunnel oldTunnel = selectedTunnel;
-        if (Objects.equals(oldTunnel, tunnel))
-            return;
-        selectedTunnel = tunnel;
-        onSelectedTunnelChanged(oldTunnel, tunnel);
-        selectionChangeRegistry.notifyCallbacks(oldTunnel, 0, tunnel);
-    }
-
-    public interface OnSelectedTunnelChangedListener {
-        void onSelectedTunnelChanged(@Nullable ObservableTunnel oldTunnel, @Nullable ObservableTunnel newTunnel);
-    }
-
-    private static final class SelectionChangeNotifier
-            extends NotifierCallback<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel> {
-        @Override
-        public void onNotifyCallback(final OnSelectedTunnelChangedListener listener,
-                                     final ObservableTunnel oldTunnel, final int ignored,
-                                     final ObservableTunnel newTunnel) {
-            listener.onSelectedTunnelChanged(oldTunnel, newTunnel);
-        }
-    }
-
-    private static final class SelectionChangeRegistry
-            extends CallbackRegistry<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel> {
-        private SelectionChangeRegistry() {
-            super(new SelectionChangeNotifier());
-        }
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt b/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt
new file mode 100644
index 00000000..ebf2e161
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/BaseActivity.kt
@@ -0,0 +1,79 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.os.Bundle
+import androidx.databinding.CallbackRegistry
+import androidx.databinding.CallbackRegistry.NotifierCallback
+import com.wireguard.android.Application
+import com.wireguard.android.model.ObservableTunnel
+
+/**
+ * Base class for activities that need to remember the currently-selected tunnel.
+ */
+abstract class BaseActivity : ThemeChangeAwareActivity() {
+    private val selectionChangeRegistry = SelectionChangeRegistry()
+    var selectedTunnel: ObservableTunnel? = null
+        set(value) {
+            val oldTunnel = field
+            if (oldTunnel == value) return
+            field = value
+            onSelectedTunnelChanged(oldTunnel, value)
+            selectionChangeRegistry.notifyCallbacks(oldTunnel, 0, value)
+        }
+    fun addOnSelectedTunnelChangedListener(listener: OnSelectedTunnelChangedListener) {
+        selectionChangeRegistry.add(listener)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        // Restore the saved tunnel if there is one; otherwise grab it from the arguments.
+        val savedTunnelName = when {
+            savedInstanceState != null -> savedInstanceState.getString(KEY_SELECTED_TUNNEL)
+            intent != null -> intent.getStringExtra(KEY_SELECTED_TUNNEL)
+            else -> null
+        }
+        if (savedTunnelName != null) {
+            Application.getTunnelManager()
+                    .tunnels
+                    .thenAccept { selectedTunnel = it[savedTunnelName] }
+        }
+
+        // The selected tunnel must be set before the superclass method recreates fragments.
+        super.onCreate(savedInstanceState)
+    }
+
+    override fun onSaveInstanceState(outState: Bundle) {
+        if (selectedTunnel != null) outState.putString(KEY_SELECTED_TUNNEL, selectedTunnel!!.name)
+        super.onSaveInstanceState(outState)
+    }
+
+    protected abstract fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?, newTunnel: ObservableTunnel?)
+    fun removeOnSelectedTunnelChangedListener(
+            listener: OnSelectedTunnelChangedListener) {
+        selectionChangeRegistry.remove(listener)
+    }
+
+    interface OnSelectedTunnelChangedListener {
+        fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?, newTunnel: ObservableTunnel?)
+    }
+
+    private class SelectionChangeNotifier : NotifierCallback<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel>() {
+        override fun onNotifyCallback(
+                listener: OnSelectedTunnelChangedListener,
+                oldTunnel: ObservableTunnel?,
+                ignored: Int,
+                newTunnel: ObservableTunnel?
+        ) {
+            listener.onSelectedTunnelChanged(oldTunnel, newTunnel)
+        }
+    }
+
+    private class SelectionChangeRegistry :
+            CallbackRegistry<OnSelectedTunnelChangedListener, ObservableTunnel, ObservableTunnel>(SelectionChangeNotifier())
+
+    companion object {
+        private const val KEY_SELECTED_TUNNEL = "selected_tunnel"
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/activity/MainActivity.java b/ui/src/main/java/com/wireguard/android/activity/MainActivity.java
deleted file mode 100644
index 61ae63e3..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/MainActivity.java
+++ /dev/null
@@ -1,147 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.annotation.SuppressLint;
-import android.content.Intent;
-import android.os.Bundle;
-import android.view.Menu;
-import android.view.MenuItem;
-import android.widget.LinearLayout;
-
-import com.wireguard.android.R;
-import com.wireguard.android.fragment.TunnelDetailFragment;
-import com.wireguard.android.fragment.TunnelEditorFragment;
-import com.wireguard.android.model.ObservableTunnel;
-import com.wireguard.util.NonNullForAll;
-
-import java.util.List;
-
-import androidx.annotation.Nullable;
-import androidx.appcompat.app.ActionBar;
-import androidx.fragment.app.Fragment;
-import androidx.fragment.app.FragmentManager;
-import androidx.fragment.app.FragmentTransaction;
-
-/**
- * CRUD interface for WireGuard tunnels. This activity serves as the main entry point to the
- * WireGuard application, and contains several fragments for listing, viewing details of, and
- * editing the configuration and interface state of WireGuard tunnels.
- */
-
-@NonNullForAll
-public class MainActivity extends BaseActivity
-        implements FragmentManager.OnBackStackChangedListener {
-    @Nullable private ActionBar actionBar;
-    private boolean isTwoPaneLayout;
-
-    @Override
-    public void onBackPressed() {
-        final int backStackEntries = getSupportFragmentManager().getBackStackEntryCount();
-        // If the two-pane layout does not have an editor open, going back should exit the app.
-        if (isTwoPaneLayout && backStackEntries <= 1) {
-            finish();
-            return;
-        }
-        // Deselect the current tunnel on navigating back from the detail pane to the one-pane list.
-        if (!isTwoPaneLayout && backStackEntries == 1) {
-            getSupportFragmentManager().popBackStack();
-            setSelectedTunnel(null);
-            return;
-        }
-        super.onBackPressed();
-    }
-
-    @Override public void onBackStackChanged() {
-        if (actionBar == null)
-            return;
-        // Do not show the home menu when the two-pane layout is at the detail view (see above).
-        final int backStackEntries = getSupportFragmentManager().getBackStackEntryCount();
-        final int minBackStackEntries = isTwoPaneLayout ? 2 : 1;
-        actionBar.setDisplayHomeAsUpEnabled(backStackEntries >= minBackStackEntries);
-    }
-
-    // We use onTouchListener here to avoid the UI click sound, hence
-    // calling View#performClick defeats the purpose of it.
-    @SuppressLint("ClickableViewAccessibility")
-    @Override
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        setContentView(R.layout.main_activity);
-        actionBar = getSupportActionBar();
-        isTwoPaneLayout = findViewById(R.id.master_detail_wrapper) instanceof LinearLayout;
-        getSupportFragmentManager().addOnBackStackChangedListener(this);
-        onBackStackChanged();
-        // Dispatch insets on back stack change
-        // This is required to ensure replaced fragments are also able to consume insets
-        findViewById(R.id.master_detail_wrapper).setOnApplyWindowInsetsListener((v, insets) -> {
-            final FragmentManager fragmentManager = getSupportFragmentManager();
-            fragmentManager.addOnBackStackChangedListener(() -> {
-                final List<Fragment> fragments = fragmentManager.getFragments();
-                for (int i = 0; i < fragments.size(); i++) {
-                    fragments.get(i).requireView().dispatchApplyWindowInsets(insets);
-                }
-            });
-            return insets;
-        });
-    }
-
-    @Override
-    public boolean onCreateOptionsMenu(final Menu menu) {
-        getMenuInflater().inflate(R.menu.main_activity, menu);
-        return true;
-    }
-
-    @Override
-    @SuppressWarnings("UnnecessaryFullyQualifiedName")
-    public boolean onOptionsItemSelected(final MenuItem item) {
-        switch (item.getItemId()) {
-            case android.R.id.home:
-                // The back arrow in the action bar should act the same as the back button.
-                onBackPressed();
-                return true;
-            case R.id.menu_action_edit:
-                getSupportFragmentManager().beginTransaction()
-                        .replace(R.id.detail_container, new TunnelEditorFragment())
-                        .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
-                        .addToBackStack(null)
-                        .commit();
-                return true;
-            case R.id.menu_action_save:
-                // This menu item is handled by the editor fragment.
-                return false;
-            case R.id.menu_settings:
-                startActivity(new Intent(this, SettingsActivity.class));
-                return true;
-            default:
-                return super.onOptionsItemSelected(item);
-        }
-    }
-
-    @Override
-    protected void onSelectedTunnelChanged(@Nullable final ObservableTunnel oldTunnel,
-                                           @Nullable final ObservableTunnel newTunnel) {
-        final FragmentManager fragmentManager = getSupportFragmentManager();
-        final int backStackEntries = fragmentManager.getBackStackEntryCount();
-        if (newTunnel == null) {
-            // Clear everything off the back stack (all editors and detail fragments).
-            fragmentManager.popBackStackImmediate(0, FragmentManager.POP_BACK_STACK_INCLUSIVE);
-            return;
-        }
-        if (backStackEntries == 2) {
-            // Pop the editor off the back stack to reveal the detail fragment. Use the immediate
-            // method to avoid the editor picking up the new tunnel while it is still visible.
-            fragmentManager.popBackStackImmediate();
-        } else if (backStackEntries == 0) {
-            // Create and show a new detail fragment.
-            fragmentManager.beginTransaction()
-                    .add(R.id.detail_container, new TunnelDetailFragment())
-                    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
-                    .addToBackStack(null)
-                    .commit();
-        }
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/MainActivity.kt b/ui/src/main/java/com/wireguard/android/activity/MainActivity.kt
new file mode 100644
index 00000000..237a75f4
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/MainActivity.kt
@@ -0,0 +1,126 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.content.Intent
+import android.os.Bundle
+import android.view.Menu
+import android.view.MenuItem
+import android.view.View
+import android.widget.LinearLayout
+import androidx.appcompat.app.ActionBar
+import androidx.fragment.app.FragmentManager
+import androidx.fragment.app.FragmentTransaction
+import com.wireguard.android.R
+import com.wireguard.android.fragment.TunnelDetailFragment
+import com.wireguard.android.fragment.TunnelEditorFragment
+import com.wireguard.android.model.ObservableTunnel
+
+/**
+ * CRUD interface for WireGuard tunnels. This activity serves as the main entry point to the
+ * WireGuard application, and contains several fragments for listing, viewing details of, and
+ * editing the configuration and interface state of WireGuard tunnels.
+ */
+class MainActivity : BaseActivity(), FragmentManager.OnBackStackChangedListener {
+    private var actionBar: ActionBar? = null
+    private var isTwoPaneLayout = false
+
+    override fun onBackPressed() {
+        val backStackEntries = supportFragmentManager.backStackEntryCount
+        // If the two-pane layout does not have an editor open, going back should exit the app.
+        if (isTwoPaneLayout && backStackEntries <= 1) {
+            finish()
+            return
+        }
+        // Deselect the current tunnel on navigating back from the detail pane to the one-pane list.
+        if (!isTwoPaneLayout && backStackEntries == 1) {
+            supportFragmentManager.popBackStack()
+            selectedTunnel = null
+            return
+        }
+        super.onBackPressed()
+    }
+
+    override fun onBackStackChanged() {
+        if (actionBar == null) return
+        // Do not show the home menu when the two-pane layout is at the detail view (see above).
+        val backStackEntries = supportFragmentManager.backStackEntryCount
+        val minBackStackEntries = if (isTwoPaneLayout) 2 else 1
+        actionBar!!.setDisplayHomeAsUpEnabled(backStackEntries >= minBackStackEntries)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.main_activity)
+        actionBar = supportActionBar
+        isTwoPaneLayout = findViewById<View>(R.id.master_detail_wrapper) is LinearLayout
+        supportFragmentManager.addOnBackStackChangedListener(this)
+        onBackStackChanged()
+        // Dispatch insets on back stack change
+        // This is required to ensure replaced fragments are also able to consume insets
+        findViewById<View>(R.id.master_detail_wrapper).setOnApplyWindowInsetsListener { _, insets ->
+            val fragmentManager = supportFragmentManager
+            fragmentManager.addOnBackStackChangedListener {
+                fragmentManager.fragments.forEach {
+                    it.requireView().dispatchApplyWindowInsets(insets)
+                }
+            }
+            insets
+        }
+    }
+
+    override fun onCreateOptionsMenu(menu: Menu): Boolean {
+        menuInflater.inflate(R.menu.main_activity, menu)
+        return true
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        return when (item.itemId) {
+            android.R.id.home -> {
+                // The back arrow in the action bar should act the same as the back button.
+                onBackPressed()
+                true
+            }
+            R.id.menu_action_edit -> {
+                supportFragmentManager.beginTransaction()
+                        .replace(R.id.detail_container, TunnelEditorFragment())
+                        .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
+                        .addToBackStack(null)
+                        .commit()
+                true
+            }
+            // This menu item is handled by the editor fragment.
+            R.id.menu_action_save -> false
+            R.id.menu_settings -> {
+                startActivity(Intent(this, SettingsActivity::class.java))
+                true
+            }
+            else -> super.onOptionsItemSelected(item)
+        }
+    }
+
+    override fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?,
+                                         newTunnel: ObservableTunnel?) {
+        val fragmentManager = supportFragmentManager
+        val backStackEntries = fragmentManager.backStackEntryCount
+        if (newTunnel == null) {
+            // Clear everything off the back stack (all editors and detail fragments).
+            fragmentManager.popBackStackImmediate(0, FragmentManager.POP_BACK_STACK_INCLUSIVE)
+            return
+        }
+        if (backStackEntries == 2) {
+            // Pop the editor off the back stack to reveal the detail fragment. Use the immediate
+            // method to avoid the editor picking up the new tunnel while it is still visible.
+            fragmentManager.popBackStackImmediate()
+        } else if (backStackEntries == 0) {
+            // Create and show a new detail fragment.
+            fragmentManager.beginTransaction()
+                    .add(R.id.detail_container, TunnelDetailFragment())
+                    .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
+                    .addToBackStack(null)
+                    .commit()
+        }
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.java b/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.java
deleted file mode 100644
index a0726d55..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.java
+++ /dev/null
@@ -1,134 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.content.pm.PackageManager;
-import android.os.Build;
-import android.os.Bundle;
-import android.util.SparseArray;
-import android.view.MenuItem;
-
-import com.wireguard.android.Application;
-import com.wireguard.android.R;
-import com.wireguard.android.backend.WgQuickBackend;
-import com.wireguard.android.util.ModuleLoader;
-import com.wireguard.util.NonNullForAll;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.List;
-
-import androidx.annotation.Nullable;
-import androidx.core.app.ActivityCompat;
-import androidx.core.content.ContextCompat;
-import androidx.preference.Preference;
-import androidx.preference.PreferenceFragmentCompat;
-import androidx.preference.PreferenceScreen;
-
-/**
- * Interface for changing application-global persistent settings.
- */
-
-@NonNullForAll
-public class SettingsActivity extends ThemeChangeAwareActivity {
-    private final SparseArray<PermissionRequestCallback> permissionRequestCallbacks = new SparseArray<>();
-    private int permissionRequestCounter;
-
-    public void ensurePermissions(final String[] permissions, final PermissionRequestCallback cb) {
-        final List<String> needPermissions = new ArrayList<>(permissions.length);
-        for (final String permission : permissions) {
-            if (ContextCompat.checkSelfPermission(this, permission)
-                    != PackageManager.PERMISSION_GRANTED)
-                needPermissions.add(permission);
-        }
-        if (needPermissions.isEmpty()) {
-            final int[] granted = new int[permissions.length];
-            Arrays.fill(granted, PackageManager.PERMISSION_GRANTED);
-            cb.done(permissions, granted);
-            return;
-        }
-        final int idx = permissionRequestCounter++;
-        permissionRequestCallbacks.put(idx, cb);
-        ActivityCompat.requestPermissions(this,
-                needPermissions.toArray(new String[needPermissions.size()]), idx);
-    }
-
-    @Override
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
-            getSupportFragmentManager().beginTransaction()
-                    .add(android.R.id.content, new SettingsFragment())
-                    .commit();
-        }
-    }
-
-    @Override
-    @SuppressWarnings("UnnecessaryFullyQualifiedName")
-    public boolean onOptionsItemSelected(final MenuItem item) {
-        if (item.getItemId() == android.R.id.home) {
-            finish();
-            return true;
-        }
-        return super.onOptionsItemSelected(item);
-    }
-
-    @Override
-    public void onRequestPermissionsResult(final int requestCode,
-                                           final String[] permissions,
-                                           final int[] grantResults) {
-        final PermissionRequestCallback f = permissionRequestCallbacks.get(requestCode);
-        if (f != null) {
-            permissionRequestCallbacks.remove(requestCode);
-            f.done(permissions, grantResults);
-        }
-    }
-
-    public interface PermissionRequestCallback {
-        void done(String[] permissions, int[] grantResults);
-    }
-
-    public static class SettingsFragment extends PreferenceFragmentCompat {
-        @Override
-        public void onCreatePreferences(final Bundle savedInstanceState, final String key) {
-            addPreferencesFromResource(R.xml.preferences);
-            final PreferenceScreen screen = getPreferenceScreen();
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q)
-                screen.removePreference(getPreferenceManager().findPreference("dark_theme"));
-
-            final Preference[] wgQuickOnlyPrefs = {
-                    getPreferenceManager().findPreference("tools_installer"),
-                    getPreferenceManager().findPreference("restore_on_boot"),
-                    getPreferenceManager().findPreference("multiple_tunnels")
-            };
-            for (final Preference pref : wgQuickOnlyPrefs)
-                pref.setVisible(false);
-            Application.getBackendAsync().thenAccept(backend -> {
-                for (final Preference pref : wgQuickOnlyPrefs) {
-                    if (backend instanceof WgQuickBackend)
-                        pref.setVisible(true);
-                    else
-                        screen.removePreference(pref);
-                }
-            });
-
-            final Preference moduleInstaller = getPreferenceManager().findPreference("module_downloader");
-            final Preference kernelModuleDisabler = getPreferenceManager().findPreference("kernel_module_disabler");
-            moduleInstaller.setVisible(false);
-            if (ModuleLoader.isModuleLoaded()) {
-                screen.removePreference(moduleInstaller);
-            } else {
-                screen.removePreference(kernelModuleDisabler);
-                Application.getAsyncWorker().runAsync(Application.getRootShell()::start).whenComplete((v, e) -> {
-                    if (e == null)
-                        moduleInstaller.setVisible(true);
-                    else
-                        screen.removePreference(moduleInstaller);
-                });
-            }
-        }
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt b/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt
new file mode 100644
index 00000000..c7453617
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/SettingsActivity.kt
@@ -0,0 +1,115 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.content.pm.PackageManager
+import android.os.Build
+import android.os.Bundle
+import android.util.SparseArray
+import android.view.MenuItem
+import androidx.core.app.ActivityCompat
+import androidx.core.content.ContextCompat
+import androidx.preference.Preference
+import androidx.preference.PreferenceFragmentCompat
+import com.wireguard.android.Application
+import com.wireguard.android.R
+import com.wireguard.android.backend.Backend
+import com.wireguard.android.backend.WgQuickBackend
+import com.wireguard.android.util.ModuleLoader
+import java.util.ArrayList
+import java.util.Arrays
+
+/**
+ * Interface for changing application-global persistent settings.
+ */
+class SettingsActivity : ThemeChangeAwareActivity() {
+    private val permissionRequestCallbacks = SparseArray<PermissionRequestCallback>()
+    private var permissionRequestCounter = 0
+
+    fun ensurePermissions(permissions: Array<String>, cb: PermissionRequestCallback) {
+        val needPermissions: MutableList<String> = ArrayList(permissions.size)
+        permissions.forEach {
+            if (ContextCompat.checkSelfPermission(this, it) != PackageManager.PERMISSION_GRANTED) {
+                needPermissions.add(it)
+            }
+        }
+        if (needPermissions.isEmpty()) {
+            val granted = IntArray(permissions.size)
+            Arrays.fill(granted, PackageManager.PERMISSION_GRANTED)
+            cb.done(permissions, granted)
+            return
+        }
+        val idx = permissionRequestCounter++
+        permissionRequestCallbacks.put(idx, cb)
+        ActivityCompat.requestPermissions(this,
+                needPermissions.toTypedArray(), idx)
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        if (supportFragmentManager.findFragmentById(android.R.id.content) == null) {
+            supportFragmentManager.beginTransaction()
+                    .add(android.R.id.content, SettingsFragment())
+                    .commit()
+        }
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+        if (item.itemId == android.R.id.home) {
+            finish()
+            return true
+        }
+        return super.onOptionsItemSelected(item)
+    }
+
+    override fun onRequestPermissionsResult(requestCode: Int,
+                                            permissions: Array<String>,
+                                            grantResults: IntArray) {
+        val f = permissionRequestCallbacks[requestCode]
+        if (f != null) {
+            permissionRequestCallbacks.remove(requestCode)
+            f.done(permissions, grantResults)
+        }
+    }
+
+    interface PermissionRequestCallback {
+        fun done(permissions: Array<String>, grantResults: IntArray)
+    }
+
+    class SettingsFragment : PreferenceFragmentCompat() {
+        override fun onCreatePreferences(savedInstanceState: Bundle?, key: String?) {
+            addPreferencesFromResource(R.xml.preferences)
+            val screen = preferenceScreen
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) screen.removePreference(preferenceManager.findPreference("dark_theme"))
+            val wgQuickOnlyPrefs = arrayOf(
+                    preferenceManager.findPreference("tools_installer"),
+                    preferenceManager.findPreference("restore_on_boot"),
+                    preferenceManager.findPreference<Preference>("multiple_tunnels")
+            ).filterNotNull()
+            wgQuickOnlyPrefs.forEach { it.isVisible = false }
+            Application.getBackendAsync().thenAccept { backend ->
+                if (backend is WgQuickBackend) {
+                    wgQuickOnlyPrefs.forEach { it.isVisible = true }
+                } else {
+                    wgQuickOnlyPrefs.forEach { screen.removePreference(it) }
+                }
+            }
+            val moduleInstaller = preferenceManager.findPreference<Preference>("module_downloader")
+            val kernelModuleDisabler = preferenceManager.findPreference<Preference>("kernel_module_disabler")
+            moduleInstaller?.isVisible = false
+            if (ModuleLoader.isModuleLoaded()) {
+                screen.removePreference(moduleInstaller)
+            } else {
+                screen.removePreference(kernelModuleDisabler)
+                Application.getAsyncWorker().runAsync(Application.getRootShell()::start).whenComplete { _, e ->
+                    if (e == null)
+                        moduleInstaller?.isVisible = true
+                    else
+                        screen.removePreference(moduleInstaller)
+                }
+            }
+        }
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java b/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java
deleted file mode 100644
index abe053e9..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.java
+++ /dev/null
@@ -1,47 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.content.SharedPreferences;
-import android.os.Build;
-import android.os.Bundle;
-
-import com.wireguard.android.Application;
-import com.wireguard.util.NonNullForAll;
-
-import androidx.annotation.Nullable;
-import androidx.appcompat.app.AppCompatActivity;
-import androidx.appcompat.app.AppCompatDelegate;
-
-@NonNullForAll
-public abstract class ThemeChangeAwareActivity extends AppCompatActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
-    private static final String TAG = "WireGuard/" + ThemeChangeAwareActivity.class.getSimpleName();
-
-    @Override
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q)
-            Application.getSharedPreferences().registerOnSharedPreferenceChangeListener(this);
-    }
-
-    @Override
-    protected void onDestroy() {
-        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q)
-            Application.getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this);
-        super.onDestroy();
-    }
-
-    @Override
-    public void onSharedPreferenceChanged(final SharedPreferences sharedPreferences, final String key) {
-        if ("dark_theme".equals(key)) {
-            AppCompatDelegate.setDefaultNightMode(
-                    sharedPreferences.getBoolean(key, false) ?
-                            AppCompatDelegate.MODE_NIGHT_YES :
-                            AppCompatDelegate.MODE_NIGHT_NO);
-            recreate();
-        }
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.kt b/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.kt
new file mode 100644
index 00000000..bd124cbc
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/ThemeChangeAwareActivity.kt
@@ -0,0 +1,42 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.content.SharedPreferences
+import android.content.SharedPreferences.OnSharedPreferenceChangeListener
+import android.os.Build
+import android.os.Bundle
+import androidx.appcompat.app.AppCompatActivity
+import androidx.appcompat.app.AppCompatDelegate
+import com.wireguard.android.Application
+
+abstract class ThemeChangeAwareActivity : AppCompatActivity(), OnSharedPreferenceChangeListener {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
+            Application.getSharedPreferences().registerOnSharedPreferenceChangeListener(this)
+        }
+    }
+
+    override fun onDestroy() {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.Q) {
+            Application.getSharedPreferences().unregisterOnSharedPreferenceChangeListener(this)
+        }
+        super.onDestroy()
+    }
+
+    override fun onSharedPreferenceChanged(sharedPreferences: SharedPreferences, key: String) {
+        when (key) {
+            "dark_theme" -> {
+                AppCompatDelegate.setDefaultNightMode(if (sharedPreferences.getBoolean(key, false)) {
+                    AppCompatDelegate.MODE_NIGHT_YES
+                } else {
+                    AppCompatDelegate.MODE_NIGHT_NO
+                })
+                recreate()
+            }
+        }
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.java b/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.java
deleted file mode 100644
index 3dee0c00..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.java
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.os.Bundle;
-
-import com.wireguard.android.fragment.TunnelEditorFragment;
-import com.wireguard.android.model.ObservableTunnel;
-import com.wireguard.util.NonNullForAll;
-
-import androidx.annotation.Nullable;
-
-/**
- * Standalone activity for creating tunnels.
- */
-
-@NonNullForAll
-public class TunnelCreatorActivity extends BaseActivity {
-    @Override
-    @SuppressWarnings("UnnecessaryFullyQualifiedName")
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        if (getSupportFragmentManager().findFragmentById(android.R.id.content) == null) {
-            getSupportFragmentManager().beginTransaction()
-                    .add(android.R.id.content, new TunnelEditorFragment())
-                    .commit();
-        }
-    }
-
-    @Override
-    protected void onSelectedTunnelChanged(@Nullable final ObservableTunnel oldTunnel, @Nullable final ObservableTunnel newTunnel) {
-        finish();
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.kt b/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.kt
new file mode 100644
index 00000000..d3d4d4f9
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/TunnelCreatorActivity.kt
@@ -0,0 +1,27 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.os.Bundle
+import com.wireguard.android.fragment.TunnelEditorFragment
+import com.wireguard.android.model.ObservableTunnel
+
+/**
+ * Standalone activity for creating tunnels.
+ */
+class TunnelCreatorActivity : BaseActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        if (supportFragmentManager.findFragmentById(android.R.id.content) == null) {
+            supportFragmentManager.beginTransaction()
+                    .add(android.R.id.content, TunnelEditorFragment())
+                    .commit()
+        }
+    }
+
+    override fun onSelectedTunnelChanged(oldTunnel: ObservableTunnel?, newTunnel: ObservableTunnel?) {
+        finish()
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.java b/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.java
deleted file mode 100644
index 82c79b6d..00000000
--- a/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.java
+++ /dev/null
@@ -1,53 +0,0 @@
-/*
- * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package com.wireguard.android.activity;
-
-import android.content.ComponentName;
-import android.os.Build;
-import android.os.Bundle;
-import android.service.quicksettings.TileService;
-import android.util.Log;
-import android.widget.Toast;
-
-import com.wireguard.android.Application;
-import com.wireguard.android.QuickTileService;
-import com.wireguard.android.R;
-import com.wireguard.android.backend.Tunnel.State;
-import com.wireguard.android.model.ObservableTunnel;
-import com.wireguard.android.util.ErrorMessages;
-import com.wireguard.util.NonNullForAll;
-
-import androidx.annotation.Nullable;
-import androidx.annotation.RequiresApi;
-import androidx.appcompat.app.AppCompatActivity;
-
-@RequiresApi(Build.VERSION_CODES.N)
-@NonNullForAll
-public class TunnelToggleActivity extends AppCompatActivity {
-    private static final String TAG = "WireGuard/" + TunnelToggleActivity.class.getSimpleName();
-
-    @Override
-    protected void onCreate(@Nullable final Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-        final ObservableTunnel tunnel = Application.getTunnelManager().getLastUsedTunnel();
-        if (tunnel == null)
-            return;
-        tunnel.setState(State.TOGGLE).whenComplete((v, t) -> {
-            TileService.requestListeningState(this, new ComponentName(this, QuickTileService.class));
-            onToggleFinished(t);
-            finishAffinity();
-        });
-    }
-
-    private void onToggleFinished(@Nullable final Throwable throwable) {
-        if (throwable == null)
-            return;
-        final String error = ErrorMessages.get(throwable);
-        final String message = getString(R.string.toggle_error, error);
-        Log.e(TAG, message, throwable);
-        Toast.makeText(this, message, Toast.LENGTH_LONG).show();
-    }
-}
diff --git a/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.kt b/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.kt
new file mode 100644
index 00000000..928a1108
--- /dev/null
+++ b/ui/src/main/java/com/wireguard/android/activity/TunnelToggleActivity.kt
@@ -0,0 +1,44 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android.activity
+
+import android.content.ComponentName
+import android.os.Build
+import android.os.Bundle
+import android.service.quicksettings.TileService
+import android.util.Log
+import android.widget.Toast
+import androidx.annotation.RequiresApi
+import androidx.appcompat.app.AppCompatActivity
+import com.wireguard.android.Application
+import com.wireguard.android.QuickTileService
+import com.wireguard.android.R
+import com.wireguard.android.backend.Tunnel
+import com.wireguard.android.util.ErrorMessages
+
+@RequiresApi(Build.VERSION_CODES.N)
+class TunnelToggleActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val tunnel = Application.getTunnelManager().lastUsedTunnel ?: return
+        tunnel.setState(Tunnel.State.TOGGLE).whenComplete { _, t ->
+            TileService.requestListeningState(this, ComponentName(this, QuickTileService::class.java))
+            onToggleFinished(t)
+            finishAffinity()
+        }
+    }
+
+    private fun onToggleFinished(throwable: Throwable?) {
+        if (throwable == null) return
+        val error = ErrorMessages.get(throwable)
+        val message = getString(R.string.toggle_error, error)
+        Log.e(TAG, message, throwable)
+        Toast.makeText(this, message, Toast.LENGTH_LONG).show()
+    }
+
+    companion object {
+        private val TAG = "WireGuard/" + TunnelToggleActivity::class.java.simpleName
+    }
+}
diff --git a/ui/src/main/java/com/wireguard/android/preference/LogExporterPreference.kt b/ui/src/main/java/com/wireguard/android/preference/LogExporterPreference.kt
index b4671309..e49de5e2 100644
--- a/ui/src/main/java/com/wireguard/android/preference/LogExporterPreference.kt
+++ b/ui/src/main/java/com/wireguard/android/preference/LogExporterPreference.kt
@@ -13,6 +13,7 @@ import androidx.preference.Preference
 import com.google.android.material.snackbar.Snackbar
 import com.wireguard.android.Application
 import com.wireguard.android.R
+import com.wireguard.android.activity.SettingsActivity
 import com.wireguard.android.util.DownloadsFileSaver
 import com.wireguard.android.util.ErrorMessages
 import com.wireguard.android.util.FragmentUtils
@@ -80,12 +81,16 @@ class LogExporterPreference(context: Context, attrs: AttributeSet?) : Preference
     override fun getTitle() = context.getString(R.string.log_export_title)
 
     override fun onClick() {
-        FragmentUtils.getPrefActivity(this).ensurePermissions(arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE)) { _, granted ->
-            if (granted.isNotEmpty() && granted[0] == PackageManager.PERMISSION_GRANTED) {
-                isEnabled = false
-                exportLog()
-            }
-        }
+        FragmentUtils.getPrefActivity(this)
+                .ensurePermissions(arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
+                        object: SettingsActivity.PermissionRequestCallback {
+                            override fun done(permissions: Array<String>, grantResults: IntArray) {
+                                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                                    isEnabled = false
+                                    exportLog()
+                                }
+                            }
+                        })
     }
 
     companion object {
diff --git a/ui/src/main/java/com/wireguard/android/preference/ZipExporterPreference.kt b/ui/src/main/java/com/wireguard/android/preference/ZipExporterPreference.kt
index 2a77f36c..db1b7735 100644
--- a/ui/src/main/java/com/wireguard/android/preference/ZipExporterPreference.kt
+++ b/ui/src/main/java/com/wireguard/android/preference/ZipExporterPreference.kt
@@ -13,6 +13,7 @@ import androidx.preference.Preference
 import com.google.android.material.snackbar.Snackbar
 import com.wireguard.android.Application
 import com.wireguard.android.R
+import com.wireguard.android.activity.SettingsActivity
 import com.wireguard.android.model.ObservableTunnel
 import com.wireguard.android.util.DownloadsFileSaver
 import com.wireguard.android.util.ErrorMessages
@@ -84,12 +85,16 @@ class ZipExporterPreference(context: Context, attrs: AttributeSet?) : Preference
     override fun getTitle() = context.getString(R.string.zip_export_title)
 
     override fun onClick() {
-        FragmentUtils.getPrefActivity(this).ensurePermissions(arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE)) { _, granted ->
-            if (granted.isNotEmpty() && granted[0] == PackageManager.PERMISSION_GRANTED) {
-                isEnabled = false
-                exportZip()
-            }
-        }
+        FragmentUtils.getPrefActivity(this)
+                .ensurePermissions(arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
+                        object : SettingsActivity.PermissionRequestCallback {
+                            override fun done(permissions: Array<String>, grantResults: IntArray) {
+                                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                                    isEnabled = false
+                                    exportZip()
+                                }
+                            }
+                        })
     }
 
     companion object {