Upgrade/Sidegrade/Downgrade subscriptions

docs/PurchaseSubscription.md

@@ -24,6 +24,21 @@ Task<InAppBillingPurchase> PurchaseAsync(string productId, ItemType itemType, st
 
 The `payload` attribute is a special payload that is sent and then returned from the server for additional validation. It can be whatever you want it to be, but should be a constant that is used anywhere the `payload` is used.
 
+A subscription can also be upgraded/downgraded/sidegraded to another subscription. This implementation is Android specific because iOS handles this automatically when purchasing subscriptions from the same subscriptions group.
+
+```csharp
+/// <summary>
+/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+/// </summary>
+/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+/// <param name="payload">Developer specific payload (can not be null)</param>
+/// <param name="verifyPurchase">Verify Purchase implementation</param>
+/// <returns>Purchase details</returns>
+/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
+Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null);
+```
+
 Example:
 ```csharp
 public async Task<bool> PurchaseItem(string productId, string payload)

src/Plugin.InAppBilling.Abstractions/BaseInAppBilling.cs

@@ -79,14 +79,24 @@ public async Task<IEnumerable<InAppBillingPurchase>> GetPurchasesAsync(ItemType
 		/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
 		public abstract Task<InAppBillingPurchase> PurchaseAsync(string productId, ItemType itemType, string payload, IInAppBillingVerifyPurchase verifyPurchase = null);
 
-        /// <summary>
-        /// Consume a purchase with a purchase token.
-        /// </summary>
-        /// <param name="productId">Id or Sku of product</param>
-        /// <param name="purchaseToken">Original Purchase Token</param>
-        /// <returns>If consumed successful</returns>
-        /// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
-        public abstract Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken);
+		/// <summary>
+		/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+		/// </summary>
+		/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+		/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+		/// <param name="payload">Developer specific payload (can not be null)</param>
+		/// <param name="verifyPurchase">Verify Purchase implementation</param>
+		/// <returns>Purchase details</returns>
+		public abstract Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null);
+
+		/// <summary>
+		/// Consume a purchase with a purchase token.
+		/// </summary>
+		/// <param name="productId">Id or Sku of product</param>
+		/// <param name="purchaseToken">Original Purchase Token</param>
+		/// <returns>If consumed successful</returns>
+		/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
+		public abstract Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken);
 
         /// <summary>
         /// Consume a purchase
@@ -137,5 +147,6 @@ public virtual void Dispose(bool disposing)
 		public virtual Task<bool> FinishTransaction(InAppBillingPurchase purchase) => Task.FromResult(true);
 
 		public virtual Task<bool> FinishTransaction(string purchaseId) => Task.FromResult(true);
+
 	}
 }

src/Plugin.InAppBilling.Abstractions/IInAppBilling.cs

@@ -64,14 +64,25 @@ public interface IInAppBilling : IDisposable
         /// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
         Task<InAppBillingPurchase> PurchaseAsync(string productId, ItemType itemType, string payload, IInAppBillingVerifyPurchase verifyPurchase = null);
 
-        /// <summary>
-        /// Consume a purchase with a purchase token.
-        /// </summary>
-        /// <param name="productId">Id or Sku of product</param>
-        /// <param name="purchaseToken">Original Purchase Token</param>
-        /// <returns>If consumed successful</returns>
-        /// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
-        Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken);
+		/// <summary>
+		/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+		/// </summary>
+		/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+		/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+		/// <param name="payload">Developer specific payload (can not be null)</param>
+		/// <param name="verifyPurchase">Verify Purchase implementation</param>
+		/// <returns>Purchase details</returns>
+		/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
+		Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null);
+
+		/// <summary>
+		/// Consume a purchase with a purchase token.
+		/// </summary>
+		/// <param name="productId">Id or Sku of product</param>
+		/// <param name="purchaseToken">Original Purchase Token</param>
+		/// <returns>If consumed successful</returns>
+		/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
+		Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken);
 
         /// <summary>
         /// Consume a purchase

src/Plugin.InAppBilling.Android/InAppBillingImplementation.cs

@@ -30,7 +30,10 @@ public class InAppBillingImplementation : BaseInAppBilling
         const string ITEM_TYPE_INAPP = "inapp";
         const string ITEM_TYPE_SUBSCRIPTION = "subs";
 
-        const string RESPONSE_CODE = "RESPONSE_CODE";
+		const string EXTRA_SUB_PARAM_REPLACED_SKUS = "skusToReplace";
+
+
+		const string RESPONSE_CODE = "RESPONSE_CODE";
         const string RESPONSE_BUY_INTENT = "BUY_INTENT";
         const string RESPONSE_IAP_DATA = "INAPP_PURCHASE_DATA";
         const string RESPONSE_IAP_DATA_SIGNATURE = "INAPP_DATA_SIGNATURE";
@@ -281,7 +284,127 @@ public async override Task<InAppBillingPurchase> PurchaseAsync(string productId,
             };
         }
 
-        async Task<Purchase> PurchaseAsync(string productSku, string itemType, string payload, IInAppBillingVerifyPurchase verifyPurchase)
+		/// <summary>
+		/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+		/// </summary>
+		/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+		/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+		/// <param name="payload">Developer specific payload (can not be null)</param>
+		/// <param name="verifyPurchase">Verify Purchase implementation</param>
+		/// <returns>Purchase details</returns>
+		public async override Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null)
+		{
+			if (payload == null)
+				throw new ArgumentNullException(nameof(payload), "Payload can not be null");
+
+
+			if (serviceConnection?.Service == null)
+			{
+				throw new InAppBillingPurchaseException(PurchaseError.ServiceUnavailable, "You are not connected to the Google Play App store.");
+			}
+
+			Purchase purchase = await UpgradePurchasedSubscriptionInternalAsync(oldProductId, newProductId, payload, verifyPurchase);
+
+			if (purchase == null)
+				return null;
+
+			var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+
+			return new InAppBillingPurchase
+			{
+				TransactionDateUtc = epoch + TimeSpan.FromMilliseconds(purchase.PurchaseTime),
+				Id = purchase.OrderId,
+				AutoRenewing = purchase.AutoRenewing,
+				PurchaseToken = purchase.PurchaseToken,
+				State = purchase.SubscriptionState,
+				ConsumptionState = purchase.ConsumedState,
+				ProductId = purchase.ProductId,
+				Payload = purchase.DeveloperPayload ?? string.Empty
+			};
+		}
+
+		async Task<Purchase> UpgradePurchasedSubscriptionInternalAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null)
+		{
+			string itemType = ITEM_TYPE_SUBSCRIPTION;
+
+			lock (purchaseLocker)
+			{
+				if (tcsPurchase != null && !tcsPurchase.Task.IsCompleted)
+					return null;
+
+				Bundle extraParams = new Bundle();
+				extraParams.PutStringArrayList(EXTRA_SUB_PARAM_REPLACED_SKUS, new List<string> { oldProductId });
+				Bundle buyIntentBundle = serviceConnection.Service.GetBuyIntentExtraParams(6, Context.PackageName, newProductId, itemType, payload, extraParams);
+				var response = GetResponseCodeFromBundle(buyIntentBundle);
+
+				switch (response)
+				{
+					case 0:
+						//OK to purchase
+						break;
+					case 1:
+						//User Cancelled, should try again
+						throw new InAppBillingPurchaseException(PurchaseError.UserCancelled);
+					case 2:
+						//Network connection is down
+						throw new InAppBillingPurchaseException(PurchaseError.ServiceUnavailable);
+					case 3:
+						//Billing Unavailable
+						throw new InAppBillingPurchaseException(PurchaseError.BillingUnavailable);
+					case 4:
+						//Item Unavailable
+						throw new InAppBillingPurchaseException(PurchaseError.ItemUnavailable);
+					case 5:
+						//Developer Error
+						throw new InAppBillingPurchaseException(PurchaseError.DeveloperError);
+					case 6:
+						//Generic Error
+						throw new InAppBillingPurchaseException(PurchaseError.GeneralError);
+					case 7:
+						//already purchased
+						throw new InAppBillingPurchaseException(PurchaseError.AlreadyOwned);
+				}
+
+
+				var pendingIntent = buyIntentBundle.GetParcelable(RESPONSE_BUY_INTENT) as PendingIntent;
+				if (pendingIntent == null)
+					throw new InAppBillingPurchaseException(PurchaseError.GeneralError);
+
+				tcsPurchase = new TaskCompletionSource<PurchaseResponse>();
+
+				Context.StartIntentSenderForResult(pendingIntent.IntentSender, PURCHASE_REQUEST_CODE, new Intent(), 0, 0, 0);
+			}
+
+			var result = await tcsPurchase.Task;
+
+			if (result == null)
+				return null;
+
+			var data = result.PurchaseData;
+			var sign = result.DataSignature;
+
+			//for some reason the data didn't come back
+			if (string.IsNullOrWhiteSpace(data))
+			{
+				var purchases = await GetPurchasesAsync(itemType, verifyPurchase);
+
+				var purchase = purchases.FirstOrDefault(p => p.ProductId == newProductId && payload.Equals(p.DeveloperPayload ?? string.Empty));
+
+				return purchase;
+			}
+
+			if (verifyPurchase == null || await verifyPurchase.VerifyPurchase(data, sign))
+			{
+				var purchase = JsonConvert.DeserializeObject<Purchase>(data);
+				if (purchase.ProductId == newProductId && payload.Equals(purchase.DeveloperPayload ?? string.Empty))
+					return purchase;
+			}
+
+			return null;
+
+		}
+
+		async Task<Purchase> PurchaseAsync(string productSku, string itemType, string payload, IInAppBillingVerifyPurchase verifyPurchase)
         {
             lock (purchaseLocker)
             {

src/Plugin.InAppBilling.UWP/InAppBillingImplementation.cs

@@ -105,14 +105,27 @@ public async override Task<InAppBillingPurchase> PurchaseAsync(string productId,
 
         }
 
-        /// <summary>
-        /// Consume a purchase with a purchase token.
-        /// </summary>
-        /// <param name="productId">Id or Sku of product</param>
-        /// <param name="purchaseToken">Original Purchase Token</param>
-        /// <returns>If consumed successful</returns>
-        /// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
-        public async override Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken)
+		/// <summary>
+		/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+		/// </summary>
+		/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+		/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+		/// <param name="payload">Developer specific payload (can not be null)</param>
+		/// <param name="verifyPurchase">Verify Purchase implementation</param>
+		/// <returns>Purchase details</returns>
+		public async override Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null)
+		{
+			throw new NotImplementedException("UWP not supported. Windows store can't manage subscriptions upgrades.");
+		}
+
+		/// <summary>
+		/// Consume a purchase with a purchase token.
+		/// </summary>
+		/// <param name="productId">Id or Sku of product</param>
+		/// <param name="purchaseToken">Original Purchase Token</param>
+		/// <returns>If consumed successful</returns>
+		/// <exception cref="InAppBillingPurchaseException">If an error occures during processing</exception>
+		public async override Task<InAppBillingPurchase> ConsumePurchaseAsync(string productId, string purchaseToken)
         {
             var result = await CurrentAppMock.ReportConsumableFulfillmentAsync(InTestingMode, productId, new Guid(purchaseToken));
             switch(result)

src/Plugin.InAppBilling.iOS/InAppBillingImplementation.cs

@@ -211,7 +211,20 @@ public async override Task<InAppBillingPurchase> PurchaseAsync(string productId,
 			return validated ? purchase : null;
 		}
 
-		Task<bool> ValidateReceipt(IInAppBillingVerifyPurchase verifyPurchase, string productId, string transactionId)
+		/// <summary>
+		/// (Android specific) Upgrade/Downagrade a previously purchased subscription
+		/// </summary>
+		/// <param name="oldProductId">Sku or ID of product that needs to be upgraded</param>
+		/// <param name="newProductId">Sku or ID of product that will replace the old one</param>
+		/// <param name="payload">Developer specific payload (can not be null)</param>
+		/// <param name="verifyPurchase">Verify Purchase implementation</param>
+		/// <returns>Purchase details</returns>
+		public async override Task<InAppBillingPurchase> UpgradePurchasedSubscriptionAsync(string oldProductId, string newProductId, string payload, IInAppBillingVerifyPurchase verifyPurchase = null)
+		{
+			throw new NotImplementedException("iOS not supported. Apple store manages upgrades natively when subscriptions of the same group are purchased.");
+		}
+
+			Task<bool> ValidateReceipt(IInAppBillingVerifyPurchase verifyPurchase, string productId, string transactionId)
 		{
 			if (verifyPurchase == null)
 				return Task.FromResult(true);