migrate to alarm manager

To make sure the messages keep getting sent while the app is in doze,
remove foreground service and instead use alarm manager to explicitly
schedule publishing messages. Also, request disabling of battery
optimization in Android 6+.

Due to Android policy, less than 15 minutes schedule is not allowed, so
adapted allowed schedule range.

README.md

@@ -30,6 +30,7 @@ certificate via:
 * INTERNET: only necessary if your MQTT server is not running locally
 * FOREGROUND_SERVICE: necessary to send notifications
 * RECEIVE_BOOT_COMPLETED: necessary to start service on start-up
+* REQUEST_IGNORE_BATTERY_OPTIMIZATIONS: on Android 6+, necessary to request disabling battery optimization
 * WRITE_EXTERNAL_STORAGE: only necessary if you want to export log files in Android 4.0 - 4.3
 
 ## Future ideas

app/build.gradle

@@ -1,3 +1,5 @@
+import org.apache.tools.ant.taskdefs.condition.Os
+
 plugins {
     id 'com.jaredsburrows.license' version '0.8.42'
     id 'pl.allegro.tech.build.axion-release' version '1.10.2'
@@ -63,13 +65,25 @@ android {
 }
 
 afterEvaluate {
-    preBuild.dependsOn(licenseDebugReport)
+    preBuild.dependsOn(generateLicenseFile)
+}
+
+// work around empty license file bug
+// see https://github.com/jaredsburrows/gradle-license-plugin/issues/38
+task generateLicenseFile(type: Exec) {
+    workingDir project.rootDir
+    if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+        commandLine 'gradlew.bat', 'app:licenseReleaseReport'
+    } else {
+        commandLine './gradlew', 'app:licenseReleaseReport'
+    }
 }
 
 dependencies {
     implementation 'androidx.appcompat:appcompat:1.1.0'
     implementation 'androidx.preference:preference:1.1.0'
     implementation 'androidx.security:security-crypto:1.0.0-alpha02'
+    implementation 'androidx.work:work-runtime:2.2.0'
     implementation('com.hypertrack:hyperlog:0.0.10') {
         exclude group: 'com.android.support'
         exclude group: 'com.android.volley'

app/src/main/AndroidManifest.xml

@@ -10,6 +10,7 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
     <uses-permission android:name="android.permission.INTERNET" />
     <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
+    <uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS" />
     <uses-permission
         android:name="android.permission.WRITE_EXTERNAL_STORAGE"
         android:maxSdkVersion="18" />
@@ -32,10 +33,6 @@
             </intent-filter>
         </activity>
 
-        <service
-            android:name=".ForegroundService"
-            android:enabled="true" />
-
         <receiver android:name=".receiver.SystemBroadcastReceiver">
             <intent-filter>
                 <action android:name="android.intent.action.BOOT_COMPLETED" />

app/src/main/java/org/ostrya/presencepublisher/Application.java

@@ -1,18 +1,44 @@
 package org.ostrya.presencepublisher;
 
+import android.content.IntentFilter;
+import android.net.ConnectivityManager;
+import android.os.Build;
 import android.util.Log;
 import com.hypertrack.hyperlog.HyperLog;
 import org.ostrya.presencepublisher.log.CustomLogFormat;
+import org.ostrya.presencepublisher.receiver.SystemBroadcastReceiver;
+import org.ostrya.presencepublisher.ui.notification.NotificationFactory;
 
 public class Application extends android.app.Application {
+    public static final int PERMISSION_REQUEST_CODE = 1;
+    public static final int LOCATION_REQUEST_CODE = 2;
+    public static final int BATTERY_OPTIMIZATION_REQUEST_CODE = 3;
+    public static final int ALARM_REQUEST_CODE = 4;
+    public static final int MAIN_ACTIVITY_REQUEST_CODE = 5;
+
     @Override
     public void onCreate() {
         super.onCreate();
+        initLogger();
+        initNetworkReceiver();
+        NotificationFactory.createNotificationChannel(this);
+    }
+
+    private void initLogger() {
         HyperLog.initialize(this, new CustomLogFormat(this));
         if (BuildConfig.DEBUG) {
             HyperLog.setLogLevel(Log.VERBOSE);
         } else {
             HyperLog.setLogLevel(Log.INFO);
         }
     }
+
+    @SuppressWarnings("deprecation")
+    private void initNetworkReceiver() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
+            SystemBroadcastReceiver receiver = new SystemBroadcastReceiver();
+            IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
+            registerReceiver(receiver, filter);
+        }
+    }
 }