[in_app_purchase] Adds Dart BillingClient APIs for loading purchases (f…

…lutter#1286)

1. Wires the Purchase data class and serializes in to Dart.
2. BillingClient now required a callback for responding to Purchase
   updates to be passed in at construction time.
3. Exposes `BillingClient#queryPurchases` and
   `BillingClient#queryPurchaseHistory`.

For now GooglePlayConnection passes in a lambda that does nothing to
`BillingClient`. This will need to be fixed when all the collections are
updated.

packages/in_app_purchase/android/src/main/java/io/flutter/plugins/inapppurchase/Translator.java

@@ -56,6 +56,7 @@ static HashMap<String, Object> fromPurchase(Purchase purchase) {
     info.put("signature", purchase.getSignature());
     info.put("sku", purchase.getSku());
     info.put("isAutoRenewing", purchase.isAutoRenewing());
+    info.put("originalJson", purchase.getOriginalJson());
     return info;
   }
 

packages/in_app_purchase/example/android/app/src/test/java/io/flutter/plugins/inapppurchase/TranslatorTest.java

@@ -140,6 +140,7 @@ private void assertSerialized(Purchase expected, Map<String, Object> serialized)
     assertEquals(expected.getPurchaseTime(), serialized.get("purchaseTime"));
     assertEquals(expected.getPurchaseToken(), serialized.get("purchaseToken"));
     assertEquals(expected.getSignature(), serialized.get("signature"));
+    assertEquals(expected.getOriginalJson(), serialized.get("originalJson"));
     assertEquals(expected.getSku(), serialized.get("sku"));
   }
 }

packages/in_app_purchase/lib/billing_client_wrappers.dart

@@ -3,4 +3,5 @@
 // found in the LICENSE file.
 
 export 'src/billing_client_wrappers/billing_client_wrapper.dart';
+export 'src/billing_client_wrappers/purchase_wrapper.dart';
 export 'src/billing_client_wrappers/sku_details_wrapper.dart';

packages/in_app_purchase/lib/src/billing_client_wrappers/billing_client_wrapper.dart

@@ -7,12 +7,33 @@ import 'package:flutter/services.dart';
 import 'package:flutter/foundation.dart';
 import 'package:json_annotation/json_annotation.dart';
 import '../channel.dart';
+import 'purchase_wrapper.dart';
 import 'sku_details_wrapper.dart';
 import 'enum_converters.dart';
 
+const String _kOnPurchasesUpdated =
+    'PurchasesUpdatedListener#onPurchasesUpdated(int, List<Purchase>)';
 const String _kOnBillingServiceDisconnected =
     'BillingClientStateListener#onBillingServiceDisconnected()';
 
+/// Callback triggered by Play in response to purchase activity.
+///
+/// This callback is triggered in response to all purchase activity while an
+/// instance of `BillingClient` is active. This includes purchases initiated by
+/// the app ([BillingClient.launchBillingFlow]) as well as purchases made in
+/// Play itself while this app is open.
+///
+/// This does not provide any hooks for purchases made in the past. See
+/// [BillingClient.queryPurchases] and [BillingClient.queryPurchaseHistory].
+///
+/// All purchase information should also be verified manually, with your server
+/// if at all possible. See ["Verify a
+/// purchase"](https://developer.android.com/google/play/billing/billing_library_overview#Verify).
+///
+/// Wraps a
+/// [`PurchasesUpdatedListener`](https://developer.android.com/reference/com/android/billingclient/api/PurchasesUpdatedListener.html).
+typedef void PurchasesUpdatedListener(PurchasesResultWrapper purchasesResult);
+
 /// This class can be used directly instead of [InAppPurchaseConnection] to call
 /// Play-specific billing APIs.
 ///
@@ -26,8 +47,10 @@ const String _kOnBillingServiceDisconnected =
 /// some minor changes to account for language differences. Callbacks have been
 /// converted to futures where appropriate.
 class BillingClient {
-  BillingClient() {
+  BillingClient(PurchasesUpdatedListener onPurchasesUpdated) {
+    assert(onPurchasesUpdated != null);
     channel.setMethodCallHandler(_callHandler);
+    _callbacks[_kOnPurchasesUpdated] = [onPurchasesUpdated];
   }
 
   // Occasionally methods in the native layer require a Dart callback to be
@@ -111,8 +134,8 @@ class BillingClient {
   /// to complete the transaction there.
   ///
   /// This method returns a [BillingResponse] representing the initial attempt
-  /// to show the Google Play purchase screen.
-  /// TODO(mklim, flutter/flutter#26326): Expose onPurchasesUpdated() result.
+  /// to show the Google Play billing flow. Actual purchase updates are
+  /// delivered via the [PurchasesUpdatedListener].
   ///
   /// This method calls through to
   /// [`BillingClient#launchBillingFlow`](https://developer.android.com/reference/com/android/billingclient/api/BillingClient#launchbillingflow).
@@ -134,8 +157,52 @@ class BillingClient {
         arguments));
   }
 
+  /// Fetches recent purchases for the given [SkuType].
+  ///
+  /// This only fetches whatever purchase history Play happens to have cached
+  /// in memory.
+  ///
+  /// All purchase information should also be verified manually, with your server
+  /// if at all possible. See ["Verify a
+  /// purchase"](https://developer.android.com/google/play/billing/billing_library_overview#Verify).
+  ///
+  /// This wraps [`BillingClient#queryPurchases(String
+  /// skutype)`](https://developer.android.com/reference/com/android/billingclient/api/BillingClient#querypurchases).
+  Future<PurchasesResultWrapper> queryPurchases(SkuType skuType) async {
+    assert(skuType != null);
+    return PurchasesResultWrapper.fromJson(await channel.invokeMapMethod(
+        'BillingClient#queryPurchases(String)',
+        <String, dynamic>{'skuType': SkuTypeConverter().toJson(skuType)}));
+  }
+
+  /// Fetches purchase history for the given [SkuType].
+  ///
+  /// This makes a network request via Play and returns the most recent purchase
+  /// for each [SkuDetailsWrapper] of the given [SkuType].
+  ///
+  /// All purchase information should also be verified manually, with your
+  /// server if at all possible. See ["Verify a
+  /// purchase"](https://developer.android.com/google/play/billing/billing_library_overview#Verify).
+  ///
+  /// This wraps [`BillingClient#queryPurchaseHistoryAsync(String skuType,
+  /// PurchaseHistoryResponseListener
+  /// listener)`](https://developer.android.com/reference/com/android/billingclient/api/BillingClient#querypurchasehistoryasync).
+  Future<PurchasesResultWrapper> queryPurchaseHistory(SkuType skuType) async {
+    assert(skuType != null);
+    return PurchasesResultWrapper.fromJson(await channel.invokeMapMethod(
+        'BillingClient#queryPurchaseHistoryAsync(String, PurchaseHistoryResponseListener)',
+        <String, dynamic>{'skuType': SkuTypeConverter().toJson(skuType)}));
+  }
+
   Future<void> _callHandler(MethodCall call) async {
     switch (call.method) {
+      case _kOnPurchasesUpdated:
+        // The purchases updated listener is a singleton.
+        assert(_callbacks[_kOnPurchasesUpdated].length == 1);
+        final PurchasesUpdatedListener listener =
+            _callbacks[_kOnPurchasesUpdated].first;
+        listener(PurchasesResultWrapper.fromJson(call.arguments));
+        break;
       case _kOnBillingServiceDisconnected:
         final int handle = call.arguments['handle'];
         await _callbacks[_kOnBillingServiceDisconnected][handle]();

packages/in_app_purchase/lib/src/billing_client_wrappers/purchase_wrapper.dart

@@ -0,0 +1,132 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import 'dart:ui' show hashValues;
+import 'package:flutter/foundation.dart';
+import 'package:json_annotation/json_annotation.dart';
+import 'enum_converters.dart';
+import 'billing_client_wrapper.dart';
+
+// WARNING: Changes to `@JsonSerializable` classes need to be reflected in the
+// below generated file. Run `flutter packages pub run build_runner watch` to
+// rebuild and watch for further changes.
+part 'purchase_wrapper.g.dart';
+
+/// Data structure reprenting a succesful purchase.
+///
+/// All purchase information should also be verified manually, with your
+/// server if at all possible. See ["Verify a
+/// purchase"](https://developer.android.com/google/play/billing/billing_library_overview#Verify).
+///
+/// This wraps [`com.android.billlingclient.api.Purchase`](https://developer.android.com/reference/com/android/billingclient/api/Purchase)
+@JsonSerializable()
+class PurchaseWrapper {
+  @visibleForTesting
+  PurchaseWrapper({
+    @required this.orderId,
+    @required this.packageName,
+    @required this.purchaseTime,
+    @required this.purchaseToken,
+    @required this.signature,
+    @required this.sku,
+    @required this.isAutoRenewing,
+    @required this.originalJson,
+  });
+
+  factory PurchaseWrapper.fromJson(Map map) => _$PurchaseWrapperFromJson(map);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) return true;
+    if (other.runtimeType != runtimeType) return false;
+    final PurchaseWrapper typedOther = other;
+    return typedOther.orderId == orderId &&
+        typedOther.packageName == packageName &&
+        typedOther.purchaseTime == purchaseTime &&
+        typedOther.purchaseToken == purchaseToken &&
+        typedOther.signature == signature &&
+        typedOther.sku == sku &&
+        typedOther.isAutoRenewing == isAutoRenewing &&
+        typedOther.originalJson == originalJson;
+  }
+
+  @override
+  int get hashCode => hashValues(orderId, packageName, purchaseTime,
+      purchaseToken, signature, sku, isAutoRenewing, originalJson);
+
+  /// The unique ID for this purchase. Corresponds to the Google Payments order
+  /// ID.
+  final String orderId;
+
+  /// The package name the purchase was made from.
+  final String packageName;
+
+  /// When the purchase was made, as an epoch timestamp.
+  final int purchaseTime;
+
+  /// A unique ID for a given [SkuDetailsWrapper], user, and purchase.
+  final String purchaseToken;
+
+  /// Signature of purchase data, signed with the developer's private key. Uses
+  /// RSASSA-PKCS1-v1_5.
+  final String signature;
+
+  /// The product ID of this purchase.
+  final String sku;
+
+  /// True for subscriptions that renew automatically. Does not apply to
+  /// [SkuType.inapp] products.
+  ///
+  /// For [SkuType.subs] this means that the subscription is canceled when it is
+  /// false.
+  final bool isAutoRenewing;
+
+  /// Details about this purchase, in JSON.
+  ///
+  /// This can be used verify a purchase. See ["Verify a purchase on a
+  /// device"](https://developer.android.com/google/play/billing/billing_library_overview#Verify-purchase-device).
+  /// Note though that verifying a purchase locally is inherently insecure (see
+  /// the article for more details).
+  final String originalJson;
+}
+
+/// A data struct representing the result of a transaction.
+///
+/// Contains a potentially empty list of [PurchaseWrapper]s and a
+/// [BillingResponse] to signify the overall state of the transaction.
+///
+/// Wraps [`com.android.billingclient.api.Purchase.PurchasesResult`](https://developer.android.com/reference/com/android/billingclient/api/Purchase.PurchasesResult).
+@JsonSerializable()
+@BillingResponseConverter()
+class PurchasesResultWrapper {
+  PurchasesResultWrapper(
+      {@required BillingResponse this.responseCode,
+      @required List<PurchaseWrapper> this.purchasesList});
+
+  factory PurchasesResultWrapper.fromJson(Map map) =>
+      _$PurchasesResultWrapperFromJson(map);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) return true;
+    if (other.runtimeType != runtimeType) return false;
+    final PurchasesResultWrapper typedOther = other;
+    return typedOther.responseCode == responseCode &&
+        typedOther.purchasesList == purchasesList;
+  }
+
+  @override
+  int get hashCode => hashValues(responseCode, purchasesList);
+
+  /// The status of the operation.
+  ///
+  /// This can represent either the status of the "query purchase history" half
+  /// of the operation and the "user made purchases" transaction itself.
+  final BillingResponse responseCode;
+
+  /// The list of succesful purchases made in this transaction.
+  ///
+  /// May be empty, especially if [responseCode] is not [BillingResponse.ok].
+  final List<PurchaseWrapper> purchasesList;
+}

packages/in_app_purchase/lib/src/in_app_purchase_connection/google_play_connection.dart

@@ -16,7 +16,10 @@ import 'product_details.dart';
 class GooglePlayConnection
     with WidgetsBindingObserver
     implements InAppPurchaseConnection {
-  GooglePlayConnection._() : _billingClient = BillingClient() {
+  GooglePlayConnection._()
+      : _billingClient = BillingClient((PurchasesResultWrapper _) {
+          // TODO(mklim): wire this in to the generic interface
+        }) {
     _readyFuture = _connect();
     WidgetsBinding.instance.addObserver(this);
   }