Create a service

android/app/build.gradle

@@ -48,7 +48,6 @@ android {
     }
 
     defaultConfig {
-        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
         applicationId "org.communiquons.comunic"
         minSdkVersion 21
         targetSdkVersion 30

android/app/src/main/AndroidManifest.xml

@@ -15,6 +15,11 @@
     <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
     <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
 
+    <!-- This is required for independent push notifications service to work
+            (when FCM service can not be used) -->
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
+
     <!-- This is required on Android 11+ for image picker -->
     <queries>
         <intent>
@@ -26,9 +31,6 @@
         </intent>
     </queries>
 
-    <!-- This is required for independent push notifications service to work
-            (when FCM service can not be used) -->
-    <uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
 
     <!-- io.flutter.app.FlutterApplication is an android.app.Application that
          calls FlutterMain.startInitialization(this); in its onCreate method.
@@ -79,5 +81,18 @@
             android:name="com.yalantis.ucrop.UCropActivity"
             android:screenOrientation="portrait"
             android:theme="@style/Theme.AppCompat.Light.NoActionBar" />
+
+        <!-- Independent push notifications service -->
+        <service android:name=".independentnotifications.NotificationsService" />
+
+        <!-- Boot receiver to start independent push notifications service -->
+        <receiver android:name=".BootReceiver"
+            android:enabled="true"
+            android:exported="false">
+            <intent-filter>
+                <!-- Cold boot -->
+                <action android:name="android.intent.action.BOOT_COMPLETED"/>
+            </intent-filter>
+        </receiver>
     </application>
 </manifest>

android/app/src/main/java/org/communiquons/comunic/BootReceiver.java

@@ -0,0 +1,24 @@
+package org.communiquons.comunic;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.util.Log;
+
+import org.communiquons.comunic.independentnotifications.NotificationsService;
+
+public class BootReceiver extends BroadcastReceiver {
+    private static final String TAG = BootReceiver.class.getSimpleName();
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        if (intent == null || !intent.getAction().equals(Intent.ACTION_BOOT_COMPLETED)) {
+            Log.e(TAG, "Invalid call to intent!");
+            return;
+        }
+
+        Log.v(TAG, "Boot received, starting independent push notifications service if required...");
+
+        NotificationsService.startService(context);
+    }
+}

android/app/src/main/java/org/communiquons/comunic/independentnotifications/NotificationsChannel.java

@@ -12,6 +12,7 @@ import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 
 public class NotificationsChannel implements MethodChannel.MethodCallHandler {
+    
     private final Context context;
 
     public NotificationsChannel(Activity context) {
@@ -21,14 +22,27 @@ public class NotificationsChannel implements MethodChannel.MethodCallHandler {
     @Override
     public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
         try {
-            if (call.method.equals("needPreConfiguration"))
-                result.success(needPreConfiguration());
+            switch (call.method) {
+                case "needPreConfiguration":
+                    result.success(needPreConfiguration());
+                    break;
 
-            else if (call.method.equals("preConfigure"))
-                preConfigure(result);
+                case "preConfigure":
+                    preConfigure(result);
+                    break;
 
-            else
-                result.notImplemented();
+                case "configure":
+                    configure((String) call.arguments, result);
+                    break;
+
+                case "disable":
+                    disable(result);
+                    break;
+
+                default:
+                    result.notImplemented();
+                    break;
+            }
         } catch (Exception e) {
             e.printStackTrace();
             result.error("Failed to execute native code!", e.getMessage(), null);
@@ -60,4 +74,21 @@ public class NotificationsChannel implements MethodChannel.MethodCallHandler {
         result.success(null);
     }
 
+    /**
+     * Configure Independent Push Notifications service
+     *
+     * @param wsURL The URL this service will have to connect to
+     */
+    private void configure(@NonNull String wsURL, @NonNull MethodChannel.Result result) {
+        NotificationsService.configure(wsURL, context);
+        result.success(null);
+    }
+
+    /**
+     * Disable push notifications service
+     */
+    private void disable(@NonNull MethodChannel.Result result) {
+        NotificationsService.disable(context);
+        result.success(null);
+    }
 }

android/app/src/main/java/org/communiquons/comunic/independentnotifications/NotificationsService.java

@@ -0,0 +1,107 @@
+package org.communiquons.comunic.independentnotifications;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.app.Service;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.Build;
+import android.os.IBinder;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.app.NotificationCompat;
+import androidx.core.content.ContextCompat;
+
+import org.communiquons.comunic.MainActivity;
+import org.communiquons.comunic.R;
+
+public class NotificationsService extends Service {
+    public static final String CHANNEL_ID = "IndependentPushServiceChannel";
+    private static final String INDEPENDENT_PUSH_NOTIFICATIONS_SERVICE = "independent-push-notifications-service";
+    private static final String WS_URL_PREF_KEY = "ws_url";
+
+    public static void configure(@NonNull String wsURL, @NonNull Context context) {
+        SharedPreferences prefs = context.getSharedPreferences(INDEPENDENT_PUSH_NOTIFICATIONS_SERVICE, MODE_PRIVATE);
+
+        if (prefs.getString(WS_URL_PREF_KEY, "").equals(wsURL))
+            return;
+
+        stopService(context);
+        prefs.edit().putString(WS_URL_PREF_KEY, wsURL).apply();
+        startService(context);
+    }
+
+    public static void disable(@NonNull Context context) {
+        SharedPreferences prefs = context.getSharedPreferences(INDEPENDENT_PUSH_NOTIFICATIONS_SERVICE, MODE_PRIVATE);
+        prefs.edit().remove(WS_URL_PREF_KEY).apply();
+
+        stopService(context);
+    }
+
+    public static void stopService(@NonNull Context context) {
+        Intent serviceIntent = new Intent(context, NotificationsService.class);
+        context.stopService(serviceIntent);
+    }
+
+    public static void startService(@NonNull Context context) {
+        SharedPreferences prefs = context.getSharedPreferences(INDEPENDENT_PUSH_NOTIFICATIONS_SERVICE, MODE_PRIVATE);
+
+        if (!prefs.contains(WS_URL_PREF_KEY)) {
+            System.err.println("Independent push notifications service not configured ! Skipping!");
+            return;
+        }
+
+        Intent intent = new Intent(context, NotificationsService.class);
+        ContextCompat.startForegroundService(context, intent);
+    }
+
+    @Override
+    public int onStartCommand(Intent intent, int flags, int startId) {
+        createNotificationChannel();
+
+        Intent notificationIntent = new Intent(this, MainActivity.class);
+        PendingIntent pendingIntent = PendingIntent.getActivity(this,
+                0, notificationIntent, 0);
+        Notification notification = new NotificationCompat.Builder(this, CHANNEL_ID)
+                .setContentTitle("Comunic")
+                .setContentText(getText(R.string.independent_push_notification_notification_text))
+                .setSmallIcon(R.drawable.splash_icon)
+                .setContentIntent(pendingIntent)
+                .build();
+        startForeground(1, notification);
+        
+        initService();
+        
+        return START_STICKY;
+    }
+
+    private void createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            NotificationChannel serviceChannel = new NotificationChannel(
+                    CHANNEL_ID,
+                    "Foreground Service Channel",
+                    NotificationManager.IMPORTANCE_DEFAULT
+            );
+            NotificationManager manager = getSystemService(NotificationManager.class);
+            manager.createNotificationChannel(serviceChannel);
+        }
+    }
+
+    @Nullable
+    @Override
+    public IBinder onBind(Intent intent) {
+        return null;
+    }
+    
+    private void initService() {
+        String url = getSharedPreferences(INDEPENDENT_PUSH_NOTIFICATIONS_SERVICE, MODE_PRIVATE)
+                .getString(WS_URL_PREF_KEY, null);
+        
+        System.out.println("START HEAVY WORK HERE !!!!");
+        System.out.println("Connect to " + url);
+    }
+}

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

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="independent_push_notification_notification_text">Push notifications service is running</string>
+</resources>