[in_app_purchase] Add support for InApp subscription upgrade/downgrade (flutter#2822)

Author: rahulraj64

AUTHORS

@@ -62,3 +62,4 @@ Juan Alvarez <[email protected]>
 Aleksandr Yurkovskiy <[email protected]>
 Anton Borries <[email protected]>
 Alex Li <[email protected]>
+Rahul Raj <[email protected]>

packages/in_app_purchase/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.4.1
+
+* Support InApp subscription upgrade/downgrade.
+
 ## 0.4.0
 
 * Migrate to nullsafety.

packages/in_app_purchase/README.md

@@ -178,6 +178,30 @@ and `AppStore` that the purchase has been finished.
 
 WARNING! Failure to call `InAppPurchaseConnection.completePurchase` and get a successful response within 3 days of the purchase will result a refund.
 
+### Upgrading or Downgrading an existing InApp Subscription
+
+In order to upgrade/downgrade an existing InApp subscription on `PlayStore`, 
+you need to provide an instance of `ChangeSubscriptionParam` with the old 
+`PurchaseDetails` that the user needs to migrate from, and an optional `ProrationMode`
+with the `PurchaseParam` object while calling `InAppPurchaseConnection.buyNonConsumable`.
+`AppStore` does not require this since they provides a subscription grouping mechanism. 
+Each subscription you offer must be assigned to a subscription group. 
+So the developers can group related subscriptions together to prevents users from 
+accidentally purchasing multiple subscriptions.
+Please refer to the 'Creating a Subscription Group' sections of [Apple's subscription guide](https://developer.apple.com/app-store/subscriptions/)
+
+
+```dart
+final PurchaseDetails oldPurchaseDetails = ...;
+PurchaseParam purchaseParam = PurchaseParam(
+    productDetails: productDetails,
+    changeSubscriptionParam: ChangeSubscriptionParam(
+        oldPurchaseDetails: oldPurchaseDetails,
+        prorationMode: ProrationMode.immediateWithTimeProration));
+InAppPurchaseConnection.instance
+    .buyNonConsumable(purchaseParam: purchaseParam);
+```
+
 ## Development
 
 This plugin uses

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

@@ -20,6 +20,7 @@
 import com.android.billingclient.api.BillingClient;
 import com.android.billingclient.api.BillingClientStateListener;
 import com.android.billingclient.api.BillingFlowParams;
+import com.android.billingclient.api.BillingFlowParams.ProrationMode;
 import com.android.billingclient.api.BillingResult;
 import com.android.billingclient.api.ConsumeParams;
 import com.android.billingclient.api.ConsumeResponseListener;
@@ -39,6 +40,8 @@ class MethodCallHandlerImpl
     implements MethodChannel.MethodCallHandler, Application.ActivityLifecycleCallbacks {
 
   private static final String TAG = "InAppPurchasePlugin";
+  private static final String LOAD_SKU_DOC_URL =
+      "https://github.com/flutter/plugins/blob/master/packages/in_app_purchase/README.md#loading-products-for-sale";
 
   @Nullable private BillingClient billingClient;
   private final BillingClientFactory billingClientFactory;
@@ -120,7 +123,13 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
         break;
       case InAppPurchasePlugin.MethodNames.LAUNCH_BILLING_FLOW:
         launchBillingFlow(
-            (String) call.argument("sku"), (String) call.argument("accountId"), result);
+            (String) call.argument("sku"),
+            (String) call.argument("accountId"),
+            (String) call.argument("oldSku"),
+            call.hasArgument("prorationMode")
+                ? (int) call.argument("prorationMode")
+                : ProrationMode.UNKNOWN_SUBSCRIPTION_UPGRADE_DOWNGRADE_POLICY,
+            result);
         break;
       case InAppPurchasePlugin.MethodNames.QUERY_PURCHASES:
         queryPurchases((String) call.argument("skuType"), result);
@@ -189,7 +198,11 @@ public void onSkuDetailsResponse(
   }
 
   private void launchBillingFlow(
-      String sku, @Nullable String accountId, MethodChannel.Result result) {
+      String sku,
+      @Nullable String accountId,
+      @Nullable String oldSku,
+      int prorationMode,
+      MethodChannel.Result result) {
     if (billingClientError(result)) {
       return;
     }
@@ -198,7 +211,26 @@ private void launchBillingFlow(
     if (skuDetails == null) {
       result.error(
           "NOT_FOUND",
-          "Details for sku " + sku + " are not available. Has this ID already been fetched?",
+          String.format(
+              "Details for sku %s are not available. It might because skus were not fetched prior to the call. Please fetch the skus first. An example of how to fetch the skus could be found here: %s",
+              sku, LOAD_SKU_DOC_URL),
+          null);
+      return;
+    }
+
+    if (oldSku == null
+        && prorationMode != ProrationMode.UNKNOWN_SUBSCRIPTION_UPGRADE_DOWNGRADE_POLICY) {
+      result.error(
+          "IN_APP_PURCHASE_REQUIRE_OLD_SKU",
+          "launchBillingFlow failed because oldSku is null. You must provide a valid oldSku in order to use a proration mode.",
+          null);
+      return;
+    } else if (oldSku != null && !cachedSkus.containsKey(oldSku)) {
+      result.error(
+          "IN_APP_PURCHASE_INVALID_OLD_SKU",
+          String.format(
+              "Details for sku %s are not available. It might because skus were not fetched prior to the call. Please fetch the skus first. An example of how to fetch the skus could be found here: %s",
+              oldSku, LOAD_SKU_DOC_URL),
           null);
       return;
     }
@@ -218,6 +250,12 @@ private void launchBillingFlow(
     if (accountId != null && !accountId.isEmpty()) {
       paramsBuilder.setAccountId(accountId);
     }
+    if (oldSku != null && !oldSku.isEmpty()) {
+      paramsBuilder.setOldSku(oldSku);
+    }
+    // The proration mode value has to match one of the following declared in
+    // https://developer.android.com/reference/com/android/billingclient/api/BillingFlowParams.ProrationMode
+    paramsBuilder.setReplaceSkusProrationMode(prorationMode);
     result.success(
         Translator.fromBillingResult(
             billingClient.launchBillingFlow(activity, paramsBuilder.build())));
@@ -252,7 +290,8 @@ private void queryPurchases(String skuType, MethodChannel.Result result) {
       return;
     }
 
-    // Like in our connect call, consider the billing client responding a "success" here regardless of status code.
+    // Like in our connect call, consider the billing client responding a "success" here regardless
+    // of status code.
     result.success(fromPurchasesResult(billingClient.queryPurchases(skuType)));
   }
 
@@ -295,7 +334,8 @@ public void onBillingSetupFinished(BillingResult billingResult) {
               return;
             }
             alreadyFinished = true;
-            // Consider the fact that we've finished a success, leave it to the Dart side to validate the responseCode.
+            // Consider the fact that we've finished a success, leave it to the Dart side to
+            // validate the responseCode.
             result.success(Translator.fromBillingResult(billingResult));
           }
 

packages/in_app_purchase/example/README.md

@@ -30,7 +30,8 @@ below.
 
    - `consumable`: A managed product.
    - `upgrade`: A managed product.
-   - `subscription`: A subscription.
+   - `subscription_silver`: A lower level subscription.
+   - `subscription_gold`: A higher level subscription.
 
    Make sure that all of the products are set to `ACTIVE`.
 

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

@@ -18,6 +18,7 @@
 import static io.flutter.plugins.inapppurchase.Translator.fromSkuDetailsList;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
+import static java.util.Collections.unmodifiableList;
 import static java.util.stream.Collectors.toList;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
@@ -261,7 +262,7 @@ public void querySkuDetailsAsync_clientDisconnected() {
   }
 
   @Test
-  public void launchBillingFlow_ok_nullAccountId() {
+  public void launchBillingFlow_ok_null_AccountId() {
     // Fetch the sku details first and then prepare the launch billing flow call
     String skuId = "foo";
     queryForSkus(singletonList(skuId));
@@ -292,6 +293,40 @@ public void launchBillingFlow_ok_nullAccountId() {
     verify(result, times(1)).success(fromBillingResult(billingResult));
   }
 
+  @Test
+  public void launchBillingFlow_ok_null_OldSku() {
+    // Fetch the sku details first and then prepare the launch billing flow call
+    String skuId = "foo";
+    String accountId = "account";
+    queryForSkus(singletonList(skuId));
+    HashMap<String, Object> arguments = new HashMap<>();
+    arguments.put("sku", skuId);
+    arguments.put("accountId", accountId);
+    arguments.put("oldSku", null);
+    MethodCall launchCall = new MethodCall(LAUNCH_BILLING_FLOW, arguments);
+
+    // Launch the billing flow
+    BillingResult billingResult =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    when(mockBillingClient.launchBillingFlow(any(), any())).thenReturn(billingResult);
+    methodChannelHandler.onMethodCall(launchCall, result);
+
+    // Verify we pass the arguments to the billing flow
+    ArgumentCaptor<BillingFlowParams> billingFlowParamsCaptor =
+        ArgumentCaptor.forClass(BillingFlowParams.class);
+    verify(mockBillingClient).launchBillingFlow(any(), billingFlowParamsCaptor.capture());
+    BillingFlowParams params = billingFlowParamsCaptor.getValue();
+    assertEquals(params.getSku(), skuId);
+    assertEquals(params.getAccountId(), accountId);
+    assertNull(params.getOldSku());
+    // Verify we pass the response code to result
+    verify(result, never()).error(any(), any(), any());
+    verify(result, times(1)).success(fromBillingResult(billingResult));
+  }
+
   @Test
   public void launchBillingFlow_ok_null_Activity() {
     methodChannelHandler.setActivity(null);
@@ -311,6 +346,42 @@ public void launchBillingFlow_ok_null_Activity() {
     verify(result, never()).success(any());
   }
 
+  @Test
+  public void launchBillingFlow_ok_oldSku() {
+    // Fetch the sku details first and query the method call
+    String skuId = "foo";
+    String accountId = "account";
+    String oldSkuId = "oldFoo";
+    queryForSkus(unmodifiableList(asList(skuId, oldSkuId)));
+    HashMap<String, Object> arguments = new HashMap<>();
+    arguments.put("sku", skuId);
+    arguments.put("accountId", accountId);
+    arguments.put("oldSku", oldSkuId);
+    MethodCall launchCall = new MethodCall(LAUNCH_BILLING_FLOW, arguments);
+
+    // Launch the billing flow
+    BillingResult billingResult =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    when(mockBillingClient.launchBillingFlow(any(), any())).thenReturn(billingResult);
+    methodChannelHandler.onMethodCall(launchCall, result);
+
+    // Verify we pass the arguments to the billing flow
+    ArgumentCaptor<BillingFlowParams> billingFlowParamsCaptor =
+        ArgumentCaptor.forClass(BillingFlowParams.class);
+    verify(mockBillingClient).launchBillingFlow(any(), billingFlowParamsCaptor.capture());
+    BillingFlowParams params = billingFlowParamsCaptor.getValue();
+    assertEquals(params.getSku(), skuId);
+    assertEquals(params.getAccountId(), accountId);
+    assertEquals(params.getOldSku(), oldSkuId);
+
+    // Verify we pass the response code to result
+    verify(result, never()).error(any(), any(), any());
+    verify(result, times(1)).success(fromBillingResult(billingResult));
+  }
+
   @Test
   public void launchBillingFlow_ok_AccountId() {
     // Fetch the sku details first and query the method call
@@ -344,6 +415,79 @@ public void launchBillingFlow_ok_AccountId() {
     verify(result, times(1)).success(fromBillingResult(billingResult));
   }
 
+  @Test
+  public void launchBillingFlow_ok_Proration() {
+    // Fetch the sku details first and query the method call
+    String skuId = "foo";
+    String oldSkuId = "oldFoo";
+    String accountId = "account";
+    int prorationMode = BillingFlowParams.ProrationMode.IMMEDIATE_AND_CHARGE_PRORATED_PRICE;
+    queryForSkus(unmodifiableList(asList(skuId, oldSkuId)));
+    HashMap<String, Object> arguments = new HashMap<>();
+    arguments.put("sku", skuId);
+    arguments.put("accountId", accountId);
+    arguments.put("oldSku", oldSkuId);
+    arguments.put("prorationMode", prorationMode);
+    MethodCall launchCall = new MethodCall(LAUNCH_BILLING_FLOW, arguments);
+
+    // Launch the billing flow
+    BillingResult billingResult =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    when(mockBillingClient.launchBillingFlow(any(), any())).thenReturn(billingResult);
+    methodChannelHandler.onMethodCall(launchCall, result);
+
+    // Verify we pass the arguments to the billing flow
+    ArgumentCaptor<BillingFlowParams> billingFlowParamsCaptor =
+        ArgumentCaptor.forClass(BillingFlowParams.class);
+    verify(mockBillingClient).launchBillingFlow(any(), billingFlowParamsCaptor.capture());
+    BillingFlowParams params = billingFlowParamsCaptor.getValue();
+    assertEquals(params.getSku(), skuId);
+    assertEquals(params.getAccountId(), accountId);
+    assertEquals(params.getOldSku(), oldSkuId);
+    assertEquals(params.getReplaceSkusProrationMode(), prorationMode);
+
+    // Verify we pass the response code to result
+    verify(result, never()).error(any(), any(), any());
+    verify(result, times(1)).success(fromBillingResult(billingResult));
+  }
+
+  @Test
+  public void launchBillingFlow_ok_Proration_with_null_OldSku() {
+    // Fetch the sku details first and query the method call
+    String skuId = "foo";
+    String accountId = "account";
+    String queryOldSkuId = "oldFoo";
+    String oldSkuId = null;
+    int prorationMode = BillingFlowParams.ProrationMode.IMMEDIATE_AND_CHARGE_PRORATED_PRICE;
+    queryForSkus(unmodifiableList(asList(skuId, queryOldSkuId)));
+    HashMap<String, Object> arguments = new HashMap<>();
+    arguments.put("sku", skuId);
+    arguments.put("accountId", accountId);
+    arguments.put("oldSku", oldSkuId);
+    arguments.put("prorationMode", prorationMode);
+    MethodCall launchCall = new MethodCall(LAUNCH_BILLING_FLOW, arguments);
+
+    // Launch the billing flow
+    BillingResult billingResult =
+        BillingResult.newBuilder()
+            .setResponseCode(100)
+            .setDebugMessage("dummy debug message")
+            .build();
+    when(mockBillingClient.launchBillingFlow(any(), any())).thenReturn(billingResult);
+    methodChannelHandler.onMethodCall(launchCall, result);
+
+    // Assert that we sent an error back.
+    verify(result)
+        .error(
+            contains("IN_APP_PURCHASE_REQUIRE_OLD_SKU"),
+            contains("launchBillingFlow failed because oldSku is null"),
+            any());
+    verify(result, never()).success(any());
+  }
+
   @Test
   public void launchBillingFlow_clientDisconnected() {
     // Prepare the launch call after disconnecting the client
@@ -381,6 +525,27 @@ public void launchBillingFlow_skuNotFound() {
     verify(result, never()).success(any());
   }
 
+  @Test
+  public void launchBillingFlow_oldSkuNotFound() {
+    // Try to launch the billing flow for a random sku ID
+    establishConnectedBillingClient(null, null);
+    String skuId = "foo";
+    String accountId = "account";
+    String oldSkuId = "oldSku";
+    queryForSkus(singletonList(skuId));
+    HashMap<String, Object> arguments = new HashMap<>();
+    arguments.put("sku", skuId);
+    arguments.put("accountId", accountId);
+    arguments.put("oldSku", oldSkuId);
+    MethodCall launchCall = new MethodCall(LAUNCH_BILLING_FLOW, arguments);
+
+    methodChannelHandler.onMethodCall(launchCall, result);
+
+    // Assert that we sent an error back.
+    verify(result).error(contains("IN_APP_PURCHASE_INVALID_OLD_SKU"), contains(oldSkuId), any());
+    verify(result, never()).success(any());
+  }
+
   @Test
   public void queryPurchases() {
     establishConnectedBillingClient(null, null);