Extract notification creation process to external class

app/src/main/java/io/bartek/service/ForegroundNotificationFactory.kt

@@ -0,0 +1,69 @@
+package io.bartek.service
+
+import android.annotation.SuppressLint
+import android.app.Notification
+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 io.bartek.MainActivity
+import io.bartek.R
+
+class ForegroundNotificationFactory(private val context: Context) {
+    private val oreo: Boolean
+        get() = Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
+
+    fun createForegroundNotification(port: Int): Notification {
+        createNotificationChannel()
+
+        val pendingIntent = createPendingIntent()
+
+        return buildNotification(port, pendingIntent)
+    }
+
+    @Suppress("DEPRECATION")
+    private fun buildNotification(port: Int, pendingIntent: PendingIntent?) =
+        provideNotificationBuilder()
+            .setContentTitle(context.resources.getString(R.string.service_notification_title))
+            .setContentText(context.resources.getString(R.string.service_notification_text, port))
+            .setContentIntent(pendingIntent)
+            .setSmallIcon(R.drawable.ic_foreground_service)
+            .setTicker(context.getString(R.string.service_notification_text))
+            .setPriority(Notification.PRIORITY_HIGH) // for under android 26 compatibility
+            .build()
+
+    @SuppressLint("NewApi")
+    private fun createNotificationChannel() {
+        if (oreo) {
+            val manager =
+                context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
+            val channel = NotificationChannel(
+                NOTIFICATION_CHANNEL_ID,
+                context.resources.getString(R.string.service_notification_category_name),
+                NotificationManager.IMPORTANCE_HIGH
+            ).let {
+                it.description =
+                    context.resources.getString(R.string.service_notification_category_description)
+                it
+            }
+            manager.createNotificationChannel(channel)
+        }
+    }
+
+    private fun createPendingIntent() =
+        Intent(context, MainActivity::class.java).let { notificationIntent ->
+            PendingIntent.getActivity(context, 0, notificationIntent, 0)
+        }
+
+    @Suppress("DEPRECATION")
+    @SuppressLint("NewApi")
+    private fun provideNotificationBuilder() =
+        if (oreo) Notification.Builder(context, NOTIFICATION_CHANNEL_ID)
+        else Notification.Builder(context)
+
+    companion object {
+        private const val NOTIFICATION_CHANNEL_ID = "TTSService.NOTIFICATION_CHANNEL"
+    }
+}

app/src/main/java/io/bartek/service/ForegroundService.kt

@@ -1,15 +1,11 @@
 package io.bartek.service
 
-import android.app.*
+import android.app.Service
 import android.content.Context
 import android.content.Intent
 import android.content.SharedPreferences
-import android.graphics.Color
-import android.os.Build
 import android.os.PowerManager
 import androidx.preference.PreferenceManager
-import io.bartek.MainActivity
-import io.bartek.R
 import io.bartek.preference.PreferenceKey
 import io.bartek.web.TTSServer
 
@@ -21,50 +17,12 @@ class ForegroundService : Service() {
     private var ttsServer: TTSServer? = null
     private val port: Int
         get() = preferences.getInt(PreferenceKey.PORT, 8080)
+    private val notificationFactory = ForegroundNotificationFactory(this)
 
     override fun onCreate() {
         super.onCreate()
         preferences = PreferenceManager.getDefaultSharedPreferences(this)
-        startForeground(1, createNotification())
+        startForeground(1, notificationFactory.createForegroundNotification(port))
-    }
-
-    private fun createNotification(): Notification {
-        // depending on the Android API that we're dealing with we will have
-        // to use a specific method to create the notification
-        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
-            val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager;
-            val channel = NotificationChannel(
-                NOTIFICATION_CHANNEL_ID,
-                resources.getString(R.string.service_notification_category_name),
-                NotificationManager.IMPORTANCE_HIGH
-            ).let {
-                it.description = resources.getString(R.string.service_notification_category_description)
-                it.enableLights(true)
-                it.lightColor = Color.RED
-                it.enableVibration(true)
-                it.vibrationPattern = longArrayOf(100, 200, 300, 400, 500, 400, 300, 200, 400)
-                it
-            }
-            notificationManager.createNotificationChannel(channel)
-        }
-
-        val pendingIntent: PendingIntent = Intent(this, MainActivity::class.java).let { notificationIntent ->
-            PendingIntent.getActivity(this, 0, notificationIntent, 0)
-        }
-
-        val builder: Notification.Builder = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) Notification.Builder(
-            this,
-            NOTIFICATION_CHANNEL_ID
-        ) else Notification.Builder(this)
-
-        return builder
-            .setContentTitle(resources.getString(R.string.service_notification_title))
-            .setContentText(resources.getString(R.string.service_notification_text, port))
-            .setContentIntent(pendingIntent)
-            .setSmallIcon(R.drawable.ic_foreground_service)
-            .setTicker("Ticker text")
-            .setPriority(Notification.PRIORITY_HIGH) // for under android 26 compatibility
-            .build()
     }
 
     override fun onBind(intent: Intent) = null
@@ -116,7 +74,7 @@ class ForegroundService : Service() {
         // to check whether the service is already running
         // than to place it as a static field
         var state = ServiceState.STOPPED
-        private const val NOTIFICATION_CHANNEL_ID = "TTSService.NOTIFICATION_CHANNEL"
+
         private const val WAKELOCK_TAG = "ForegroundService::lock"
         const val CHANGE_STATE = "io.bartek.service.CHANGE_STATE"
         const val STATE = "STATE"