Improvements for the Android VPN client

.gitignore

@@ -49,3 +49,4 @@ cmd/skywirevisormobile/android/app/skywire-sources.jar
 cmd/skywirevisormobile/android/app/.idea
 cmd/skywirevisormobile/android/app/build
 cmd/skywirevisormobile/android/.gradle
+cmd/skywirevisormobile/android/local.properties

cmd/skywirevisormobile/android/app/build.gradle

@@ -9,15 +9,16 @@ repositories {
     flatDir {
         dirs '.'
     }
+    maven { url 'https://jitpack.io' }
 }
 
 android {
-    compileSdkVersion 27
+    compileSdkVersion 29
 
     defaultConfig {
         applicationId "com.skywire.skycoin.vpn"
-        minSdkVersion 26
-        targetSdkVersion 27
+        minSdkVersion 21
+        targetSdkVersion 29
         versionCode 1
         versionName "1.0"
     }
@@ -34,6 +35,27 @@ android {
 
 
 dependencies {
-    implementation 'com.android.support:appcompat-v7:27.1.1'
+    // Appcompat.
+    implementation "androidx.appcompat:appcompat:1.2.0"
+    implementation 'com.google.android.material:material:1.2.1'
+    implementation "androidx.preference:preference:1.1.1"
+    implementation "androidx.recyclerview:recyclerview:1.1.0"
+    implementation "androidx.viewpager2:viewpager2:1.0.0"
+
+    // Skywire lib.
     implementation(name:'skywire', ext:'aar')
+
+    // RxJava.
+    implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
+    implementation 'io.reactivex.rxjava3:rxjava:3.0.0'
+
+    // Retrofit.
+    implementation 'com.google.code.gson:gson:2.8.5'
+    implementation 'com.squareup.retrofit2:retrofit:2.9.0'
+    implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
+    implementation 'com.squareup.retrofit2:adapter-rxjava3:2.9.0'
+    implementation 'com.squareup.retrofit2:converter-scalars:2.9.0'
+
+    // MPAndroidChart.
+    implementation 'com.github.PhilJay:MPAndroidChart:v3.1.0'
 }

cmd/skywirevisormobile/android/app/src/main/AndroidManifest.xml

@@ -1,32 +1,54 @@
 <?xml version="1.0" encoding="utf-8"?>
-<!-- Copyright 2015 The Go Authors. All rights reserved.
-     Use of this source code is governed by a BSD-style
-     license that can be found in the LICENSE file.  -->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     package="com.skywire.skycoin.vpn" >
 
     <uses-permission android:name="android.permission.INTERNET" />
-    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
 
     <application
+        android:name=".App"
         android:allowBackup="true"
-        android:label="SkywireVPN">
-        <service android:name=".SkywireVPNService"
+        android:label="@string/general_app_name"
+        android:icon="@mipmap/ic_launcher"
+        android:theme="@style/AppTheme"
+    >
+
+        <receiver
+            android:directBootAware="true"
+            android:name=".Receiver"
+            android:enabled="true">
+            <intent-filter android:priority="2000000000">
+                <action android:name="android.intent.action.BOOT_COMPLETED" />
+            </intent-filter>
+        </receiver>
+
+        <service android:name=".vpn.SkywireVPNService"
+            android:description="@string/general_service_description"
             android:permission="android.permission.BIND_VPN_SERVICE">
             <intent-filter>
                 <action android:name="android.net.VpnService"/>
             </intent-filter>
         </service>
 
         <activity
-            android:name=".MainActivity"
-            android:label="SkywireVPN" >
+            android:name=".activities.index.IndexActivity"
+            android:configChanges="keyboardHidden"
+            android:launchMode="singleTask"
+            android:label="@string/general_app_name" >
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
 
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+
+        <activity
+            android:name=".activities.apps.AppsActivity"
+            android:configChanges="keyboardHidden"
+            android:label="@string/tmp_select_apps_title" >
+        </activity>
+
     </application>
 
 </manifest>

cmd/skywirevisormobile/android/app/src/main/java/com/skywire/skycoin/vpn/App.java

@@ -0,0 +1,118 @@
+package com.skywire.skycoin.vpn;
+
+import android.app.Activity;
+import android.app.Application;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.content.Context;
+import android.os.Build;
+import android.os.Bundle;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.skywire.skycoin.vpn.helpers.HelperFunctions;
+import com.skywire.skycoin.vpn.helpers.Notifications;
+import com.skywire.skycoin.vpn.vpn.VPNCoordinator;
+
+import io.reactivex.rxjava3.plugins.RxJavaPlugins;
+
+/**
+ * Class for the main app instance.
+ */
+public class App extends Application {
+    /**
+     * Class used internally to know when there are activities being displayed.
+     */
+    private static class ActivityLifecycleCallback implements Application.ActivityLifecycleCallbacks {
+
+        // How many activities are being shown.
+        private static int foregroundActivities = 0;
+
+        // Functions for knowing when activities start and stop being shown.
+        @Override
+        public void onActivityResumed(@NonNull final Activity activity) { foregroundActivities++; }
+        @Override
+        public void onActivityStopped(@NonNull final Activity activity) { foregroundActivities--; }
+
+        /**
+         * Returns if there is at least one activity being displayed.
+         */
+        public static boolean isApplicationInForeground() { return foregroundActivities > 0; }
+
+        // Other functions needed by the interface.
+        @Override
+        public void onActivityPaused(@NonNull Activity activity) { }
+        @Override
+        public void onActivitySaveInstanceState(@NonNull Activity activity, @NonNull Bundle outState) { }
+        @Override
+        public void onActivityDestroyed(@NonNull Activity activity) { }
+        @Override
+        public void onActivityCreated(@NonNull Activity activity, @Nullable Bundle savedInstanceState) { }
+        @Override
+        public void onActivityStarted(@NonNull Activity activity) { }
+    }
+
+    /**
+     * Reference to the current app instance.
+     */
+    private static Context appContext;
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+        // Save the current app instance.
+        appContext = this;
+
+        // Ensure the singleton is initialized early.
+        VPNCoordinator.getInstance();
+
+        // Create the notification channels, but only on API 26+ because
+        // the NotificationChannel class is new and not in the support library
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            // Channel for the VPN service state updates.
+            NotificationChannel stateChannel = new NotificationChannel(
+                Notifications.NOTIFICATION_CHANNEL_ID,
+                getString(R.string.general_app_name),
+                NotificationManager.IMPORTANCE_DEFAULT
+            );
+            stateChannel.setDescription(getString(R.string.general_notification_channel_description));
+            stateChannel.setSound(null,null);
+            NotificationManager notificationManager = getSystemService(NotificationManager.class);
+            notificationManager.createNotificationChannel(stateChannel);
+
+            // Channel for alerts.
+            NotificationChannel alertsChannel = new NotificationChannel(
+                    Notifications.ALERT_NOTIFICATION_CHANNEL_ID,
+                    getString(R.string.general_alert_notification_name),
+                    NotificationManager.IMPORTANCE_HIGH
+            );
+            alertsChannel.setDescription(getString(R.string.general_alert_notification_channel_description));
+            notificationManager.createNotificationChannel(alertsChannel);
+        }
+
+        // Code for precessing errors which were not caught by the normal error management
+        // procedures RxJava has. This prevents the app to be closed by unexpected errors, mainly
+        // code trying to report events in closed observables.
+        RxJavaPlugins.setErrorHandler(throwable -> {
+            HelperFunctions.logError("ERROR INSIDE RX: ", throwable);
+        });
+
+        // Detect when activities are started and stopped.
+        registerActivityLifecycleCallbacks(new ActivityLifecycleCallback());
+    }
+
+    /**
+     * Gets the current app context.
+     */
+    public static Context getContext(){
+        return appContext;
+    }
+
+    /**
+     * Gets if the UI is being displayed.
+     */
+    public static boolean displayingUI(){
+        return ActivityLifecycleCallback.isApplicationInForeground();
+    }
+}