ui: root: rewrite in kotlin

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

ui/src/main/java/com/wireguard/android/BootShutdownReceiver.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright © 2017-2019 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package com.wireguard.android
+
+import android.content.BroadcastReceiver
+import android.content.Context
+import android.content.Intent
+import android.util.Log
+import com.wireguard.android.backend.Backend
+import com.wireguard.android.backend.WgQuickBackend
+import com.wireguard.android.util.ExceptionLoggers
+
+class BootShutdownReceiver : BroadcastReceiver() {
+    override fun onReceive(context: Context, intent: Intent) {
+        Application.getBackendAsync().thenAccept { backend: Backend? ->
+            if (backend !is WgQuickBackend) return@thenAccept
+            val action = intent.action ?: return@thenAccept
+            val tunnelManager = Application.getTunnelManager()
+            if (Intent.ACTION_BOOT_COMPLETED == action) {
+                Log.i(TAG, "Broadcast receiver restoring state (boot)")
+                tunnelManager.restoreState(false).whenComplete(ExceptionLoggers.D)
+            } else if (Intent.ACTION_SHUTDOWN == action) {
+                Log.i(TAG, "Broadcast receiver saving state (shutdown)")
+                tunnelManager.saveState()
+            }
+        }
+    }
+
+    companion object {
+        private val TAG = "WireGuard/" + BootShutdownReceiver::class.java.simpleName
+    }
+}