Add background process for checking new data and create notifications

app/build.gradle

@@ -44,6 +44,7 @@ dependencies {
     implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
     implementation 'androidx.navigation:navigation-fragment-ktx:2.1.0'
     implementation 'androidx.navigation:navigation-ui-ktx:2.1.0'
+    implementation "androidx.work:work-runtime-ktx:2.2.0"
     implementation "androidx.room:room-runtime:2.2.0-rc01"
     kapt "androidx.room:room-compiler:2.2.0-rc01"
     implementation "androidx.room:room-ktx:2.2.0-rc01"

app/src/main/AndroidManifest.xml

@@ -20,6 +20,11 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <receiver android:name=".BootCompleteReceiver">
+            <intent-filter>
+                <action android:name="android.intent.action.BOOT_COMPLETED" />
+            </intent-filter>
+        </receiver>
     </application>
 
 </manifest>

app/src/main/java/net/underdesk/circolapp/BootCompleteReceiver.kt

@@ -0,0 +1,32 @@
+/*
+ * Circolapp
+ * Copyright (C) 2019  Matteo Schiff
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import net.underdesk.circolapp.works.PollWork
+
+
+class BootCompleteReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        if (intent.action == null || intent.action != "android.intent.action.BOOT_COMPLETED") return
+        PollWork.enqueue(context)
+    }
+}

app/src/main/java/net/underdesk/circolapp/MainActivity.kt

@@ -25,6 +25,7 @@ import androidx.navigation.ui.AppBarConfiguration
 import androidx.navigation.ui.setupActionBarWithNavController
 import androidx.navigation.ui.setupWithNavController
 import com.google.android.material.bottomnavigation.BottomNavigationView
+import net.underdesk.circolapp.works.PollWork
 
 class MainActivity : AppCompatActivity() {
 
@@ -45,5 +46,7 @@ class MainActivity : AppCompatActivity() {
         )
         setupActionBarWithNavController(navController, appBarConfiguration)
         navView.setupWithNavController(navController)
+
+        PollWork.enqueue(this)
     }
 }

app/src/main/java/net/underdesk/circolapp/works/PollWork.kt

@@ -0,0 +1,128 @@
+/*
+ * Circolapp
+ * Copyright (C) 2019  Matteo Schiff
+ *
+ * This program 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.
+ *
+ * This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package net.underdesk.circolapp.works
+
+import android.app.NotificationChannel
+import android.app.NotificationManager
+import android.app.PendingIntent
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import androidx.core.app.NotificationCompat
+import androidx.core.app.NotificationManagerCompat
+import androidx.work.*
+import net.underdesk.circolapp.MainActivity
+import net.underdesk.circolapp.R
+import net.underdesk.circolapp.data.AppDatabase
+import net.underdesk.circolapp.data.Circular
+import net.underdesk.circolapp.server.DataFetcher
+import java.util.concurrent.TimeUnit
+
+
+class PollWork(appContext: Context, workerParams: WorkerParameters) :
+    Worker(appContext, workerParams) {
+
+    companion object {
+        const val CHANNEL_ID = "net.underdesk.circolapp.NEW_CIRCULAR"
+
+        private const val pollWorkName = "net.underdesk.circolapp.POLL_WORK"
+        private const val repeatIntervalMin: Long = 30
+        private const val flexIntervalMin: Long = 10
+
+        private fun getPollWorkRequest(): PeriodicWorkRequest {
+            val constraints = Constraints.Builder()
+                .setRequiredNetworkType(NetworkType.CONNECTED)
+                .build()
+
+            return PeriodicWorkRequestBuilder<PollWork>(
+                repeatIntervalMin,
+                TimeUnit.MINUTES,
+                flexIntervalMin,
+                TimeUnit.MINUTES
+            ).setConstraints(constraints).build()
+        }
+
+        fun enqueue(context: Context) {
+            WorkManager.getInstance(context)
+                .enqueueUniquePeriodicWork(
+                    pollWorkName,
+                    ExistingPeriodicWorkPolicy.KEEP,
+                    getPollWorkRequest()
+                )
+        }
+    }
+
+    override fun doWork(): Result {
+        val fetcher = DataFetcher()
+
+        val oldCirculars = AppDatabase.getInstance(applicationContext).circularDao().getCirculars()
+        val newCirculars = fetcher.getCircularsFromServer()
+
+        if (newCirculars.size != oldCirculars.size) {
+            for (i in oldCirculars.lastIndex..newCirculars.lastIndex) {
+                createNotificationChannel()
+                createNotification(newCirculars[i])
+            }
+
+            AppDatabase.getInstance(applicationContext).circularDao().deleteAll()
+            AppDatabase.getInstance(applicationContext).circularDao().insertAll(newCirculars)
+        }
+        return Result.success()
+    }
+
+    private fun createNotification(circular: Circular) {
+        val intent = Intent(applicationContext, MainActivity::class.java).apply {
+            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
+        }
+        val pendingIntent: PendingIntent =
+            PendingIntent.getActivity(applicationContext, 0, intent, 0)
+
+        val builder = NotificationCompat.Builder(applicationContext, CHANNEL_ID)
+            .setSmallIcon(R.drawable.ic_notifications_black_24dp)
+            .setContentTitle(applicationContext.getString(R.string.notification_title, circular.id))
+            .setContentText(circular.name)
+            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
+            .setContentIntent(pendingIntent)
+            .setGroup(CHANNEL_ID)
+            .setStyle(
+                NotificationCompat.BigTextStyle()
+                    .bigText(circular.name)
+            )
+
+        with(NotificationManagerCompat.from(applicationContext)) {
+            notify(circular.id.toInt(), builder.build())
+        }
+    }
+
+    private fun createNotificationChannel() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
+            val name = applicationContext.getString(R.string.channel_name)
+            val descriptionText = applicationContext.getString(R.string.channel_description)
+            val importance = NotificationManager.IMPORTANCE_DEFAULT
+            val channel = NotificationChannel(CHANNEL_ID, name, importance).apply {
+                description = descriptionText
+            }
+
+            val notificationManager: NotificationManager =
+                applicationContext.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            notificationManager.createNotificationChannel(channel)
+        }
+    }
+
+}

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

@@ -3,4 +3,9 @@
     <string name="title_circular_letters">Circular letters</string>
     <string name="title_favourites">Favourites</string>
     <string name="title_reminders">Reminders</string>
+
+    <string name="notification_title">Published circular letter number %1$d</string>
+
+    <string name="channel_name">Circular letters</string>
+    <string name="channel_description">Notify when your school issue a new circular letter</string>
 </resources>