GetCustomerInfoAPI: avoid making a request if there's any `PostRece…

…iptDataOperation` in progress (#1911)

Fixes [CSDK-419].

This is an improvement over the fix in #1292. In there, we avoided
appending on an existing `CustomerInfoOperation` if there were any
`PostReceiptDataOperation`s in progress, because those might come back
with outdated entitlements.
This fix removes that cache key hack, and instead *reuses* the entire
response to that `PostReceiptDataOperation` by "stealing" that request's
cache key.

This is perfectly captured by the existing test
`BackendPostReceiptDataTests.testGetsUpdatedSubscriberInfoAfterPost`,
added in #1292. Amazingly enough, that test still passes with one minor
change: the entire process requires one fewer API call 🎉 🐼

[CSDK-419]:
https://revenuecats.atlassian.net/browse/CSDK-419?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ

Sources/Networking/Caching/CustomerInfoCallback.swift

@@ -17,9 +17,9 @@ struct CustomerInfoCallback: CacheKeyProviding {
 
     typealias Completion = (Result<CustomerInfo, BackendError>) -> Void
 
-    let cacheKey: String
-    let source: NetworkOperation.Type
-    let completion: Completion
+    var cacheKey: String
+    var source: NetworkOperation.Type
+    var completion: Completion
 
     init(operation: CacheableNetworkOperation, completion: @escaping Completion) {
         self.cacheKey = operation.cacheKey
@@ -28,3 +28,37 @@ struct CustomerInfoCallback: CacheKeyProviding {
     }
 
 }
+
+// MARK: - CallbackCache helpers
+
+extension CallbackCache where T == CustomerInfoCallback {
+
+    func addOrAppendToPostReceiptDataOperation(callback: CustomerInfoCallback) -> CallbackCacheStatus {
+        if let existing = self.callbacks(ofType: PostReceiptDataOperation.self).last {
+            return self.add(callback: callback.withNewCacheKey(existing.cacheKey))
+        } else {
+            return self.add(callback: callback)
+        }
+    }
+
+    private func callbacks(ofType type: NetworkOperation.Type) -> [T] {
+        return self
+            .cachedCallbacksByKey
+            .value
+            .lazy
+            .flatMap(\.value)
+            .filter { $0.source == type }
+    }
+
+}
+
+private extension CustomerInfoCallback {
+
+    func withNewCacheKey(_ newKey: String) -> Self {
+        var copy = self
+        copy.cacheKey = newKey
+
+        return copy
+    }
+
+}

Sources/Networking/CustomerAPI.swift

@@ -38,7 +38,7 @@ final class CustomerAPI {
                                                  customerInfoCallbackCache: self.customerInfoCallbackCache)
 
         let callback = CustomerInfoCallback(operation: operation, completion: completion)
-        let cacheStatus = self.customerInfoCallbackCache.add(callback: callback)
+        let cacheStatus = self.customerInfoCallbackCache.addOrAppendToPostReceiptDataOperation(callback: callback)
         self.backendConfig.addCacheableOperation(operation,
                                                  withRandomDelay: randomDelay,
                                                  cacheStatus: cacheStatus)

Sources/Networking/Operations/GetCustomerInfoOperation.swift

@@ -26,18 +26,8 @@ class GetCustomerInfoOperation: CacheableNetworkOperation {
         self.customerInfoResponseHandler = customerInfoResponseHandler
         self.customerInfoCallbackCache = customerInfoCallbackCache
 
-        var individualizedCacheKeyPart = configuration.appUserID
-
-        // If there is any enqueued `PostReceiptDataOperation` we don't want this new
-        // `GetCustomerInfoOperation` to share the same cache key.
-        // If it did, future `GetCustomerInfoOperation` would receive a cached value
-        // instead of an up-to-date `CustomerInfo` after those post receipt operations finish.
-        if customerInfoCallbackCache.hasPostReceiptOperations {
-            individualizedCacheKeyPart += "-\(customerInfoCallbackCache.numberOfGetCustomerInfoOperations)"
-        }
-
         super.init(configuration: configuration,
-                   individualizedCacheKeyPart: individualizedCacheKeyPart)
+                   individualizedCacheKeyPart: configuration.appUserID)
     }
 
     override func begin(completion: @escaping () -> Void) {
@@ -72,25 +62,3 @@ private extension GetCustomerInfoOperation {
     }
 
 }
-
-private extension CallbackCache where T == CustomerInfoCallback {
-
-    var numberOfGetCustomerInfoOperations: Int {
-        return self.callbacks(ofType: GetCustomerInfoOperation.self)
-    }
-
-    var hasPostReceiptOperations: Bool {
-        return self.callbacks(ofType: PostReceiptDataOperation.self) > 0
-    }
-
-    private func callbacks(ofType type: NetworkOperation.Type) -> Int {
-        return self
-            .cachedCallbacksByKey
-            .value
-            .lazy
-            .flatMap(\.value)
-            .filter { $0.source == type }
-            .count
-    }
-
-}

Tests/UnitTests/Networking/Backend/BackendPostReceiptDataTests.swift

@@ -432,8 +432,7 @@ class BackendPostReceiptDataTests: BaseBackendTests {
 
         expect(self.httpClient.calls.map { $0.request.path }) == [
             getCustomerInfoPath,
-            .postReceiptData,
-            getCustomerInfoPath
+            .postReceiptData
         ]
     }