fix: upgrade existing Play subscription with proration instead of stacking a new purchase

Author: NickVs2015

CMakeLists.txt

@@ -4,7 +4,7 @@ set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 set(PROJECT AmneziaVPN)
-set(AMNEZIAVPN_VERSION 5.0.0.6)
+set(AMNEZIAVPN_VERSION 5.0.1.2)
 
 set(QT_CREATOR_SKIP_PACKAGE_MANAGER_SETUP ON CACHE BOOL "" FORCE)
 set(CMAKE_PROJECT_TOP_LEVEL_INCLUDES

client/android/billing/src/main/kotlin/BillingProvider.kt

@@ -264,7 +264,7 @@ class BillingProvider(context: Context) : AutoCloseable {
         val subscriptionUpdateParams = oldPurchaseToken?.let {
             BillingFlowParams.SubscriptionUpdateParams.newBuilder()
                 .setOldPurchaseToken(oldPurchaseToken)
-                .setSubscriptionReplacementMode(ReplacementMode.WITHOUT_PRORATION)
+                .setSubscriptionReplacementMode(ReplacementMode.CHARGE_PRORATED_PRICE)
                 .build()
         }
 

client/core/controllers/api/subscriptionController.cpp

@@ -981,6 +981,22 @@ ErrorCode SubscriptionController::processPlayMarketPurchase(const QString &userC
     QObject::connect(&watcher, &QFutureWatcher<QPair<bool, QString>>::finished, &waitLoop, &QEventLoop::quit);
 
     QFuture<QPair<bool, QString>> future = QtConcurrent::run([androidController, productId]() {
+        // If the user already has an active "premium" subscription, upgrade/replace it with proration
+        // instead of stacking a second, independent purchase that Google Play would just queue behind it.
+        QString oldPurchaseToken;
+        QJsonObject existingPurchasesResult = androidController->queryPurchases();
+        if (existingPurchasesResult.value("responseCode").toInt(-1) == 0) {
+            const QJsonArray existingPurchases = existingPurchasesResult.value("purchases").toArray();
+            for (const QJsonValue &purchaseValue : existingPurchases) {
+                const QJsonObject existingPurchase = purchaseValue.toObject();
+                if (existingPurchase.value("purchaseState").toInt(-1) == 1) { // PURCHASED
+                    oldPurchaseToken = existingPurchase.value("purchaseToken").toString();
+                    qInfo() << "[Billing] Found existing active subscription, will upgrade instead of purchasing a new one";
+                    break;
+                }
+            }
+        }
+
         QJsonObject plansResult = androidController->getSubscriptionPlans();
         int responseCode = plansResult.value("responseCode").toInt(-1);
         if (responseCode != 0) {
@@ -1016,7 +1032,9 @@ ErrorCode SubscriptionController::processPlayMarketPurchase(const QString &userC
             qWarning() << "[Billing] No offer token found for basePlanId:" << productId;
             return qMakePair(false, QString());
         }
-        QJsonObject purchaseResult = androidController->purchaseSubscription(offerToken);
+        QJsonObject purchaseResult = oldPurchaseToken.isEmpty()
+                ? androidController->purchaseSubscription(offerToken)
+                : androidController->upgradeSubscription(offerToken, oldPurchaseToken);
         responseCode = purchaseResult.value("responseCode").toInt(-1);
         if (responseCode != 0) {
             qWarning() << "[Billing] Purchase failed, responseCode:" << responseCode;