flutter in_app_purchase products widget

purchase_products_list.dart

import 'dart:async';
import 'dart:io';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:in_app_purchase/in_app_purchase.dart';
import 'package:cloud_functions/cloud_functions.dart';
import 'package:font_awesome_flutter/font_awesome_flutter.dart';
import 'package:in_app_purchase_storekit/in_app_purchase_storekit.dart';
import 'package:in_app_purchase_storekit/store_kit_wrappers.dart';

class PurchaseList extends StatefulWidget {
  @override
  State<PurchaseList> createState() => _PurchaseListState();
}

class _PurchaseListState extends State<PurchaseList> {
  final inAppPurchase = InAppPurchase.instance;
  late StreamSubscription<List<PurchaseDetails>> _subscription;
  List<ProductDetails> _products = <ProductDetails>[];
  bool _isPending = false;

  @override
  void initState() {
    _isPending = true;
    _getProducts();

    print('start initState()');
    final Stream<List<PurchaseDetails>> purchaseUpdated = inAppPurchase.purchaseStream;
    _subscription = purchaseUpdated.listen((List<PurchaseDetails> purchaseDetailsList) {
      _listenToPurchaseUpdated(purchaseDetailsList);
    }, onDone: () {
      _subscription.cancel();
    }, onError: (Object error) {
      print('PurchaseList initState purchaseUpdated error: $error');
      return Container();
    });
    initStoreInfo();
    super.initState();
  }

  Future<void> _getProducts() async {
    final bool available = await inAppPurchase.isAvailable();

    if (!available) {
      return [];
    }

    final _ids = <String>{ 'com.example.monthly.standard', 'com.example.yearly.standard' };
    final ProductDetailsResponse response = await inAppPurchase.queryProductDetails(_ids);
    List<ProductDetails> products;

    if (response.error != null) {
      print('_getProducts response error : ${response.error!.message}');
      products = [];
    }

    if (response.notFoundIDs.isNotEmpty) {
      print('_getProducts response.notFoundIDs.isNotEmpty: ${response.notFoundIDs}');
      products = [];
    } else {
      products = response.productDetails;
    }

    setState(() {
      _products = products;
      _isPending = false;
    });
  }

  Future<void> initStoreInfo() async {
    if (Platform.isIOS) {
      final InAppPurchaseStoreKitPlatformAddition iosPlatformAddition =
      inAppPurchase
          .getPlatformAddition<InAppPurchaseStoreKitPlatformAddition>();
      await iosPlatformAddition.setDelegate(ExamplePaymentQueueDelegate());
    }
  }

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

  @override
  Widget build(BuildContext context) {
    return Container(
      height: MediaQuery.of(context).size.height * 0.9,
      child: SingleChildScrollView(
        child: Column(
          children: [
            Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                IconButton(
                  icon: Icon(Icons.close),
                  onPressed: () => Navigator.pop(context),
                ),
              ],
            ),
            Text('有料プラン'),
            Column(children: [
              Text('サービス説明文'),
              _isPending
                  ? Center(child: CircularProgressIndicator())
                  : ListView.builder(
                  shrinkWrap: true,
                  physics: NeverScrollableScrollPhysics(),
                  padding: EdgeInsets.zero,
                  itemCount: _products.length,
                  itemBuilder: (_, i) {
                    ProductDetails product = _products[i];

                    var _buttonView;
                    var _term;
                    if (product.id.contains('monthly')) {
                      _term = " / 月額";
                    } else if (product.id.contains('yearly')) {
                      _term = " / 年額";
                    } else { // 未使用 定期購入を非表示
                      return Container();
                    }

                    _buttonView = product.price + _term;

                    return Container(
                      child: Column(
                        children: [
                          CupertinoButton.filled(
                              child: Text(_buttonView),
                              onPressed: () async {
                                PurchaseParam purchaseParam = PurchaseParam(productDetails: product);
    
                                try {
                                  await inAppPurchase.buyNonConsumable(purchaseParam: purchaseParam);
                                } catch(error) {
                                  print('inAppPurchase.buyNonConsumable: $error');
    
                                  if (error.toString().contains('storekit_duplicate_product_object')) {
                                    showDialog(
                                        context: context,
                                        builder: (context) {
                                          return CupertinoAlertDialog(
                                            title: Text('エラー'),
                                            content: Text('すでに購入済みの商品です'),
                                            actions: <Widget>[
                                              CupertinoDialogAction(child: Text("OK"),
                                                onPressed: () => Navigator.pop(context),),
                                            ],
                                          );
                                        }
                                    );
                                  }
                                }
                          }),
                          Text(product.description),
                        ],
                      ),
                    );
                  }
              ),
            ],),
            CupertinoButton(
              child: Text('Close'),
              onPressed: () => Navigator.pop(context),
            ),
          ],
        ),
      ),
    );
  }


  Future<void> _listenToPurchaseUpdated(
      List<PurchaseDetails> purchaseDetailsList) async {
  
    print('start _listenToPurchaseUpdated');
    print('purchaseDetailsList.length: ${purchaseDetailsList.length}');
  
    if (purchaseDetailsList.isEmpty) {
      print('purchaseDetailsList is empty');
      Navigator.pop(context);
      showDialog(
          context: context,
          builder: (context) {
            return CupertinoAlertDialog(
              title: Text('エラー'),
              content: Text(
                      '対象商品が見つかりませんでした\n'
                      '定期課金が停止されている可能性があります\n'
                      '購入処理をお願いします'),
              actions: <Widget>[
                CupertinoDialogAction(child: Text("OK", key),
                  onPressed: () => Navigator.pop(context),),
              ],
            );
          }
      );
    }
  
    for (final PurchaseDetails purchaseDetails in purchaseDetailsList) {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        print('_listenToPurchaseUpdated purchaseDetails.status: pending');
        setState(() {
          _isPending = false;
        });
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          print("PurchaseStatus.error: ${purchaseDetails.error!.message}");
          setState(() {
            _isPending = false;
          });
        } else if (purchaseDetails.status == PurchaseStatus.purchased ||
            purchaseDetails.status == PurchaseStatus.restored) {
          print('_listenToPurchaseUpdated purchaseDetails.status: purchased or restored');
  
          final result = await _verifyPurchase(purchaseDetails);
          print('_verifyPurchase result: $result');
          if (result == BillingConst.SUCCESS) {
            print('_listenToPurchaseUpdated _verifyPurchase: SUCCESS');
            deliverProduct(purchaseDetails);
          } else {
            print('_listenToPurchaseUpdated _verifyPurchase: ERROR');
            setState(() {
              _isPending = false;
            });
            return;
          }
        }
        if (purchaseDetails.pendingCompletePurchase) {
          print('completePurchase');
          await inAppPurchase.completePurchase(purchaseDetails);
        }
      }
    }
  }
  
  Future<int> _verifyPurchase(PurchaseDetails purchaseDetails) async {
    try {
      if (Platform.isIOS) {
        HttpsCallable verifyReceipt = FirebaseFunctions.instance.httpsCallable('verifyIos');
        final HttpsCallableResult result = await verifyReceipt.call(
            {'data': purchaseDetails.verificationData.localVerificationData});
  
        print("Verify Purchase RESULT: " + result.data.toString());
        return result.data[BillingConst.result];
      } else if (Platform.isAndroid) {
        HttpsCallable verifyReceipt = FirebaseFunctions.instance.httpsCallable('verifyAndroid');
        final HttpsCallableResult result = await verifyReceipt.call({
          'data': purchaseDetails.verificationData.localVerificationData});
  
        print("Verify Purchase RESULT: " + result.data.toString());
        return result.data[BillingConst.result];
      }
      print("_verifyPurchase not matching OS");
      return BillingConst.UNEXPECTED_ERROR;
    } catch (error) {
      print('_verifyPurchase error: $error');
      return BillingConst.UNEXPECTED_ERROR;
    }
  }
  
  Future<void> deliverProduct(PurchaseDetails purchaseDetails) async {
    if (mounted) {
      Navigator.pop(context);
    }
  }
  
  void handleError(IAPError error) {
    setState(() {
      _isPending = false;
    });
  }
}

class BillingConst {
  static const String result = 'result';
  static const SUCCESS = 0; // 成功 (期限内)
  static const EXPIRED = 1; // 期限切れ
  static const DOCUMENT_NOT_FOUND = 2; // Firestoreにドキュメントなし
  static const NO_AUTH = 3; // 認証情報なし
  static const INVALID_RECEIPT = 4; // レシート情報が不正です
  static const ALREADY_EXIST = 5; // 同じトランザクションが存在している
  static const UNEXPECTED_ERROR = 99; // 不明なエラー
}

/// Example implementation of the
/// [`SKPaymentQueueDelegate`](https://developer.apple.com/documentation/storekit/skpaymentqueuedelegate?language=objc).
///
/// The payment queue delegate can be implementated to provide information
/// needed to complete transactions.
class ExamplePaymentQueueDelegate implements SKPaymentQueueDelegateWrapper {
  @override
  bool shouldContinueTransaction(
      SKPaymentTransactionWrapper transaction, SKStorefrontWrapper storefront) {
    return true;
  }

  @override
  bool shouldShowPriceConsent() {
    return false;
  }
}