Add ServiceForegroundConnector

mobile/src/main/java/be/mygod/vpnhotspot/util/ServiceForegroundConnector.kt

@@ -0,0 +1,34 @@
+package be.mygod.vpnhotspot.util
+
+import android.app.Service
+import android.arch.lifecycle.Lifecycle
+import android.arch.lifecycle.LifecycleObserver
+import android.arch.lifecycle.LifecycleOwner
+import android.arch.lifecycle.OnLifecycleEvent
+import android.content.Context
+import android.content.Intent
+import android.content.ServiceConnection
+import android.support.v4.app.Fragment
+import kotlin.reflect.KClass
+
+/**
+ * host also needs to be Context/Fragment and LifecycleOwner.
+ */
+class ServiceForegroundConnector(private val host: ServiceConnection, private val classes: List<KClass<out Service>>) :
+        LifecycleObserver {
+    init {
+        (host as LifecycleOwner).lifecycle.addObserver(this)
+    }
+    constructor(host: ServiceConnection, vararg classes: KClass<out Service>) : this(host, classes.toList())
+
+    private val context get() = if (host is Context) host else (host as Fragment).requireContext()
+
+    @OnLifecycleEvent(Lifecycle.Event.ON_START)
+    fun onStart() {
+        val context = context
+        for (clazz in classes) context.bindService(Intent(context, clazz.java), host, Context.BIND_AUTO_CREATE)
+    }
+
+    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
+    fun onStop() = context.unbindService(host)
+}