import 'dart:async';
import 'dart:io';
import 'package:flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';
import 'package:in_app_purchase_android/in_app_purchase_android.dart';
import 'package:in_app_purchase_storekit/in_app_purchase_storekit.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();

  runApp(_MyApp());
}

const String _kSubscriptionId = 'sku_monthly_level_1'; // TODO Set subscription id for your project here
const Set<String> _kProductIds = <String>{_kSubscriptionId};

class _MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<_MyApp> {
  final InAppPurchase _inAppPurchase = InAppPurchase.instance;
  late StreamSubscription<List<PurchaseDetails>> _subscription;
  List<ProductDetails> _products = [];
  List<PurchaseDetails> _purchases = [];
  bool _isAvailable = false;
  bool _purchasePending = false;
  bool _loading = true;
  String? _queryProductError;

  @override
  void initState() {
    final Stream<List<PurchaseDetails>> purchaseUpdated = _inAppPurchase.purchaseStream;
    _subscription = purchaseUpdated.listen((purchaseDetailsList) {
      _listenToPurchaseUpdated(purchaseDetailsList);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (error) {
      // handle error here.
    });
    initStoreInfo();
    super.initState();
  }

  Future<void> initStoreInfo() async {
    final bool isAvailable = await _inAppPurchase.isAvailable();
    if (!isAvailable) {
      setState(() {
        _isAvailable = isAvailable;
        _products = [];
        _purchases = [];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }

    ProductDetailsResponse productDetailResponse = await _inAppPurchase.queryProductDetails(_kProductIds);
    if (productDetailResponse.error != null) {
      setState(() {
        _queryProductError = productDetailResponse.error!.message;
        _isAvailable = isAvailable;
        _products = productDetailResponse.productDetails;
        _purchases = [];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }

    if (productDetailResponse.productDetails.isNotEmpty) {
      setState(() {
        _queryProductError = null;
        _isAvailable = isAvailable;
        _products = productDetailResponse.productDetails;
        _purchases = [];
        _purchasePending = false;
        _loading = false;
      });
      return;
    }
  }

  @override
  void dispose() {
    if (Platform.isIOS) {
      var iosPlatformAddition = _inAppPurchase.getPlatformAddition<InAppPurchaseStoreKitPlatformAddition>();
      iosPlatformAddition.setDelegate(null);
    }
    _subscription.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    List<Widget> stack = [];
    if (_queryProductError == null) {
      stack.add(
        ListView(
          children: [
            _buildConnectionCheckTile(),
            _buildProductList(),
            _buildRestoreButton(),
          ],
        ),
      );
    } else {
      stack.add(Center(
        child: Text(_queryProductError!),
      ));
    }
    if (_purchasePending) {
      stack.add(
        Stack(
          children: [
            Opacity(
              opacity: 0.3,
              child: const ModalBarrier(dismissible: false, color: Colors.grey),
            ),
            Center(
              child: CircularProgressIndicator(),
            ),
          ],
        ),
      );
    }

    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('IAP Example'),
        ),
        body: Stack(
          children: stack,
        ),
      ),
    );
  }

  Card _buildConnectionCheckTile() {
    if (_loading) {
      return Card(child: ListTile(title: const Text('Trying to connect...')));
    }
    final Widget storeHeader = ListTile(
      leading: Icon(_isAvailable ? Icons.check : Icons.block,
          color: _isAvailable ? Colors.green : ThemeData.light().errorColor),
      title: Text('The store is ' + (_isAvailable ? 'available' : 'unavailable') + '.'),
    );
    final List<Widget> children = <Widget>[storeHeader];

    if (!_isAvailable) {
      children.addAll([
        Divider(),
        ListTile(
          title: Text('Not connected', style: TextStyle(color: ThemeData.light().errorColor)),
          subtitle: const Text(
              'Unable to connect to the payments processor. Has this app been configured correctly? See the example README for instructions.'),
        ),
      ]);
    }
    return Card(child: Column(children: children));
  }

  Card _buildProductList() {
    if (_loading) {
      return Card(child: (ListTile(leading: CircularProgressIndicator(), title: Text('Fetching products...'))));
    }
    if (!_isAvailable) {
      return Card();
    }
    final ListTile productHeader = ListTile(title: Text('Products for Sale'));
    List<ListTile> productList = <ListTile>[];

    // This loading previous purchases code is just a demo. Please do not use this as it is.
    // In your app you should always verify the purchase data using the `verificationData` inside the [PurchaseDetails] object before trusting it.
    // We recommend that you use your own server to verify the purchase data.
    Map<String, PurchaseDetails> purchases = Map.fromEntries(_purchases.map((PurchaseDetails purchase) {
      if (purchase.pendingCompletePurchase) {
        _inAppPurchase.completePurchase(purchase);
      }
      return MapEntry<String, PurchaseDetails>(purchase.productID, purchase);
    }));
    productList.addAll(_products.map(
      (ProductDetails productDetails) {
        PurchaseDetails? previousPurchase = purchases[productDetails.id];
        return ListTile(
            title: Text(
              productDetails.title,
            ),
            subtitle: Text(
              productDetails.description,
            ),
            trailing: previousPurchase != null
                ? Icon(Icons.check)
                : TextButton(
                    child: Text(productDetails.price),
                    style: TextButton.styleFrom(
                      backgroundColor: Colors.green[800],
                      primary: Colors.white,
                    ),
                    onPressed: () {
                      PurchaseParam purchaseParam = GooglePlayPurchaseParam(
                        productDetails: productDetails,
                        applicationUserName: null,
                      );
                      _inAppPurchase.buyNonConsumable(purchaseParam: purchaseParam);
                    },
                  ));
      },
    ));

    return Card(child: Column(children: <Widget>[productHeader, Divider()] + productList));
  }

  Widget _buildRestoreButton() {
    if (_loading) {
      return Container();
    }

    return Padding(
      padding: const EdgeInsets.all(4.0),
      child: Row(
        mainAxisSize: MainAxisSize.max,
        mainAxisAlignment: MainAxisAlignment.end,
        children: [
          TextButton(
            child: Text('Restore purchases'),
            style: TextButton.styleFrom(
              backgroundColor: Theme.of(context).primaryColor,
              primary: Colors.white,
            ),
            onPressed: () => _inAppPurchase.restorePurchases(),
          ),
        ],
      ),
    );
  }

  void showPendingUI() {
    setState(() {
      _purchasePending = true;
    });
  }

  void deliverProduct(PurchaseDetails purchaseDetails) async {
    // IMPORTANT!! Always verify purchase details before delivering the product.
    setState(() {
      _purchases.add(purchaseDetails);
      _purchasePending = false;
    });
  }

  void handleError(IAPError error) {
    setState(() {
      _purchasePending = false;
    });
  }

  Future<bool> _verifyPurchase(PurchaseDetails purchaseDetails) {
    // IMPORTANT!! Always verify a purchase before delivering the product.
    // For the purpose of an example, we directly return true.
    return Future<bool>.value(true);
  }

  void _handleInvalidPurchase(PurchaseDetails purchaseDetails) {
    // handle invalid purchase here if  _verifyPurchase` failed.
  }

  void _listenToPurchaseUpdated(List<PurchaseDetails> purchaseDetailsList) {
    purchaseDetailsList.forEach((PurchaseDetails purchaseDetails) async {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        showPendingUI();
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          handleError(purchaseDetails.error!);
        } else if (purchaseDetails.status == PurchaseStatus.purchased ||
            purchaseDetails.status == PurchaseStatus.restored) {
          bool valid = await _verifyPurchase(purchaseDetails);
          if (valid) {
            deliverProduct(purchaseDetails);
          } else {
            _handleInvalidPurchase(purchaseDetails);
            return;
          }
        }
        if (purchaseDetails.pendingCompletePurchase) {
          await _inAppPurchase.completePurchase(purchaseDetails);
        }
      }
    });
  }
}