main.dart

  Future<void> initPlatformState() async {
    String platformVersion;
    // Platform messages may fail, so we use a try/catch PlatformException.

    final user = await FirebaseAuth.instance.currentUser();

    try {
      platformVersion = await FlutterInappPurchase.instance.platformVersion;
    } on PlatformException {
      platformVersion = 'Failed to get platform version.';
    }

    // prepare
    var result = await FlutterInappPurchase.instance.initConnection;
    print('result: $result');

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;

    setState(() {
      _platformVersion = platformVersion;
    });

    // refresh items for android
    try {
      String msg = await FlutterInappPurchase.instance.consumeAllItems;
      print('consumeAllItems: $msg');
    } catch (err) {
      print('consumeAllItems error: $err');
    }

    _conectionSubscription =
        FlutterInappPurchase.connectionUpdated.listen((connected) {
      print('connected: $connected');
    });

    _purchaseUpdatedSubscription =
        FlutterInappPurchase.purchaseUpdated.listen((productItem) async {
      await Firestore.instance
          .collection('premium_users')
          .document(user.uid)
          .setData({
        "premium_user": true,
        "transactionDate": productItem.transactionDate,
        "transactionId": productItem.transactionId,
        "purchaseToken": productItem.purchaseToken,
        "orderId": productItem.orderId,
        "transactionReceipt": productItem.transactionReceipt,
        "productId": productItem.productId,
        "userId": user.uid,
        "userEmail": user.email,
        "userName": user.displayName
      });

      setState(() {
        _premiumUser = true;
        premium_user = true;
      });

      await FlutterInappPurchase.instance.finishTransaction(
        productItem,
        developerPayloadAndroid: productItem.developerPayloadAndroid,
        isConsumable: false,
      );

      await FlutterInappPurchase.instance
          .acknowledgePurchaseAndroid(productItem.purchaseToken);

      Navigator.pushReplacementNamed(context, RoutePaths.home);
    });

    _purchaseErrorSubscription =
        FlutterInappPurchase.purchaseError.listen((purchaseError) {
      print('purchase-error: $purchaseError');
    });
  }