i2pd-android/app/src/main/java/org/purplei2p/i2pd/ForegroundService.java

package org.purplei2p.i2pd;

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.os.Binder;
import android.os.Build;
import android.os.IBinder;

import androidx.annotation.RequiresApi;
import androidx.core.app.NotificationCompat;

import android.util.Log;

public class ForegroundService extends Service {
    private static final String TAG = "FgService";

    private volatile boolean shown;

    private final DaemonSingleton.StateUpdateListener daemonStateUpdatedListener =
            new DaemonSingleton.StateUpdateListener() {

                @Override
                public void daemonStateUpdate() {
                    try {
                        synchronized (ForegroundService.this) {
                            if (shown) cancelNotification();
                            showNotification();
                        }
                    } catch (Throwable tr) {
                        Log.e(TAG, "error ignored", tr);
                    }
                }
            };


    private NotificationManager notificationManager;

    // Unique Identification Number for the Notification.
    // We use it on Notification start, and to cancel it.
    private int NOTIFICATION = 1;

    /**
     * Class for clients to access.  Because we know this service always
     * runs in the same process as its clients, we don't need to deal with
     * IPC.
     */
    public class LocalBinder extends Binder {
        ForegroundService getService() {
            return ForegroundService.this;
        }
    }

    @Override
    public void onCreate() {
        notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);

        synchronized (this) {
            DaemonSingleton.getInstance().addStateChangeListener(daemonStateUpdatedListener);
            if (!shown) daemonStateUpdatedListener.daemonStateUpdate();
        }
        // Tell the user we started.
//		Toast.makeText(this, R.string.i2pd_service_started, Toast.LENGTH_SHORT).show();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.i("ForegroundService", "Received start id " + startId + ": " + intent);
        return START_STICKY;
    }

    @Override
    public void onDestroy() {
        DaemonSingleton.getInstance().removeStateChangeListener(daemonStateUpdatedListener);
        cancelNotification();
    }

    private synchronized void cancelNotification() {
        // Cancel the persistent notification.
        notificationManager.cancel(NOTIFICATION);

        stopForeground(true);

        // Tell the user we stopped.
        //Toast.makeText(this, R.string.i2pd_service_stopped, Toast.LENGTH_SHORT).show();
        shown = false;
    }

    @Override
    public IBinder onBind(Intent intent) {
        return mBinder;
    }

    // This is the object that receives interactions from clients.  See
    // RemoteService for a more complete example.
    private final IBinder mBinder = new LocalBinder();

    /**
     * Show a notification while this service is running.
     */
    private synchronized void showNotification() {
        // In this sample, we'll use the same text for the ticker and the expanded notification
        CharSequence text = getText(DaemonSingleton.getInstance().getState().getStatusStringResourceId());

        // The PendingIntent to launch our activity if the user selects this notification
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, I2PDActivity.class), 0);

        // If earlier version channel ID is not used
        // https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
        String channelId = Build.VERSION.SDK_INT >= 26 ? createNotificationChannel() : "";

        // Set the info for the views that show in the notification panel.
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, channelId)
                .setOngoing(true)
                .setSmallIcon(R.drawable.itoopie_notification_icon); // the status icon
        if (Build.VERSION.SDK_INT >= 16)
            builder = builder.setPriority(Notification.PRIORITY_DEFAULT);
        if (Build.VERSION.SDK_INT >= 21)
            builder = builder.setCategory(Notification.CATEGORY_SERVICE);
        Notification notification = builder
                .setTicker(text) // the status text
                .setWhen(System.currentTimeMillis()) // the time stamp
                .setContentTitle(getText(R.string.app_name)) // the label of the entry
                .setContentText(text) // the contents of the entry
                .setContentIntent(contentIntent) // The intent to send when the entry is clicked
                .build();

        // Send the notification.
        //mNM.notify(NOTIFICATION, notification);
        startForeground(NOTIFICATION, notification);
        shown = true;
    }

    @RequiresApi(Build.VERSION_CODES.O)
    private synchronized String createNotificationChannel() {
        String channelId = getString(R.string.app_name);
        CharSequence channelName = "I2Pd service";
        NotificationChannel chan = new NotificationChannel(channelId, channelName, NotificationManager.IMPORTANCE_LOW);
        //chan.setLightColor(Color.PURPLE);
        chan.setLockscreenVisibility(Notification.VISIBILITY_PRIVATE);
        NotificationManager service = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        if (service != null) service.createNotificationChannel(chan);
        else Log.e(TAG, "error: NOTIFICATION_SERVICE is null");
        return channelId;
    }

    private static final DaemonSingleton daemon = DaemonSingleton.getInstance();
}