Implement push commands

lib/push_service.dart

@@ -0,0 +1,53 @@
+import 'dart:developer' as developer;
+import 'dart:io';
+
+import 'package:firebase_messaging/firebase_messaging.dart';
+import 'package:flutter_background_geolocation/flutter_background_geolocation.dart' as bg;
+
+import 'preferences.dart';
+
+class PushService {
+  static Future<void> init() async {
+    await FirebaseMessaging.instance.requestPermission();
+    FirebaseMessaging.onBackgroundMessage(_backgroundHandler);
+    FirebaseMessaging.onMessage.listen(_onMessage);
+    FirebaseMessaging.instance.onTokenRefresh.listen(_uploadToken);
+    bg.BackgroundGeolocation.onEnabledChange((enabled) async {
+      if (enabled) {
+        _uploadToken(await FirebaseMessaging.instance.getToken());
+      }
+    });
+  }
+
+  @pragma('vm:entry-point')
+  static Future<void> _backgroundHandler(RemoteMessage message) async {
+    await Preferences.init();
+    await _onMessage(message);
+  }
+
+  static Future<void> _onMessage(RemoteMessage message) async {
+    final command = message.data['command'];
+    if (command == 'positionSingle') {
+      try {
+        await bg.BackgroundGeolocation.getCurrentPosition(samples: 1, persist: true, extras: {'remote': true});
+      } catch (error) {
+        developer.log('Failed to get position', error: error);
+      }
+    }
+  }
+
+  static Future<void> _uploadToken(String? token) async {
+    if (token == null) return;
+    final id = Preferences.instance.getString(Preferences.id);
+    final url = Preferences.instance.getString(Preferences.url);
+    if (id == null || url == null) return;
+    try {
+      final request = await HttpClient().postUrl(Uri.parse(url));
+      request.headers.contentType = ContentType.parse('application/x-www-form-urlencoded');
+      request.write('id=${Uri.encodeComponent(id)}&notificationToken=${Uri.encodeComponent(token)}');
+      await request.close();
+    } catch (error) {
+      developer.log('Failed to upload token', error: error);
+    }
+  }
+}