PermissionHelper to be used in services

PermissionHelper.java

/*
 * Copyright © 2013–2016 Michael von Glasow.
 * 
 * This file is part of LSRN Tools.
 *
 * LSRN Tools is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * LSRN Tools is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with LSRN Tools.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.vonglasow.michael.satstat.utils;

import com.vonglasow.michael.satstat.Const;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.support.v4.app.ActivityCompat;
import android.support.v4.app.NotificationCompat;
import android.support.v4.app.TaskStackBuilder;
import android.support.v4.app.ActivityCompat.OnRequestPermissionsResultCallback;
import android.support.v4.os.ResultReceiver;
import android.support.v7.app.AppCompatActivity;

/**
 * Provides helper methods to request permissions from components other than Activities.
 */
public class PermissionHelper {
	private static final String TAG = PermissionHelper.class.getSimpleName();


	/**
	 * Requests permissions to be granted to this application.
	 * 
	 * This method is a wrapper around
	 * {@link android.support.v4.app.ActivityCompat#requestPermissions(android.app.Activity, String[], int)}
	 * which works in a similar way, except it can be called from non-activity contexts. When called, it
	 * displays a notification with a customizable title and text. When the user taps the notification, an
	 * activity is launched in which the user is prompted to allow or deny the request.
	 * 
	 * After the user has made a choice,
	 * {@link android.support.v4.app.ActivityCompat.OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}
	 * is called, reporting whether the permissions were granted or not.
	 * 
	 * @param context The context from which the request was made. The context supplied must implement
	 * {@link android.support.v4.app.ActivityCompat.OnRequestPermissionsResultCallback} and will receive the
	 * result of the operation.
	 * @param permissions The requested permissions
	 * @param requestCode Application specific request code to match with a result reported to
	 * {@link android.support.v4.app.ActivityCompat.OnRequestPermissionsResultCallback#onRequestPermissionsResult(int, String[], int[])}
	 * @param notificationTitle The title for the notification
	 * @param notificationText The text for the notification
	 * @param notificationIcon Resource identifier for the notification icon
	 */
	public static <T extends Context & OnRequestPermissionsResultCallback> void requestPermissions(final T context, String[] permissions, int requestCode, String notificationTitle, String notificationText, int notificationIcon) {
		ResultReceiver resultReceiver = new ResultReceiver(new Handler(Looper.getMainLooper())) {
			@Override
			protected void onReceiveResult (int resultCode, Bundle resultData) {
				String[] outPermissions = resultData.getStringArray(Const.KEY_PERMISSIONS);
				int[] grantResults = resultData.getIntArray(Const.KEY_GRANT_RESULTS);
				context.onRequestPermissionsResult(resultCode, outPermissions, grantResults);
			}
		};

		Intent permIntent = new Intent(context, PermissionRequestActivity.class);
		permIntent.putExtra(Const.KEY_RESULT_RECEIVER, resultReceiver);
		permIntent.putExtra(Const.KEY_PERMISSIONS, permissions);
		permIntent.putExtra(Const.KEY_REQUEST_CODE, requestCode);

		TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);
		stackBuilder.addNextIntent(permIntent);

		PendingIntent permPendingIntent =
				stackBuilder.getPendingIntent(
						0,
						PendingIntent.FLAG_UPDATE_CURRENT
						);

		NotificationCompat.Builder builder = new NotificationCompat.Builder(context)
		.setSmallIcon(notificationIcon)
		.setContentTitle(notificationTitle)
		.setContentText(notificationText)
		.setOngoing(true)
		//.setCategory(Notification.CATEGORY_STATUS)
		.setAutoCancel(true)
		.setWhen(0)
		.setContentIntent(permPendingIntent)
		.setStyle(null);

		NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
		notificationManager.notify(requestCode, builder.build());
	}


	/**
	 * A blank {@link Activity} on top of which permission request dialogs can be displayed
	 */
	public static class PermissionRequestActivity extends AppCompatActivity {
		ResultReceiver resultReceiver;
		String[] permissions;
		int requestCode;

		/**
		 * Called when the user has made a choice in the permission dialog.
		 * 
		 * This method wraps the responses in a {@link Bundle} and passes it to the {@link ResultReceiver}
		 * specified in the {@link Intent} that started the activity, then closes the activity.
		 */
		@Override
		public void onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults) {
			Bundle resultData = new Bundle();
			resultData.putStringArray(Const.KEY_PERMISSIONS, permissions);
			resultData.putIntArray(Const.KEY_GRANT_RESULTS, grantResults);
			resultReceiver.send(requestCode, resultData);
			finish();
		}


		/**
		 * Called when the activity is started.
		 * 
		 * This method obtains several extras from the {@link Intent} that started the activity: the request
		 * code, the requested permissions and the {@link ResultReceiver} which will receive the results.
		 * After that, it issues the permission request.
		 */
		@Override
		protected void onStart() {
			super.onStart();

			resultReceiver = this.getIntent().getParcelableExtra(Const.KEY_RESULT_RECEIVER);
			permissions = this.getIntent().getStringArrayExtra(Const.KEY_PERMISSIONS);
			requestCode = this.getIntent().getIntExtra(Const.KEY_REQUEST_CODE, 0);

			ActivityCompat.requestPermissions(this, permissions, requestCode);
		}
	}
}