Token-changed listeners for iOS AppCheck

app_check/integration_test/src/integration_test.cc

@@ -119,6 +119,22 @@ class FirebaseAppCheckTest : public FirebaseTest {
   std::vector<firebase::database::DatabaseReference> cleanup_paths_;
 };
 
+// Listens for token changed notifications
+class TestAppCheckListener : public firebase::app_check::AppCheckListener {
+ public:
+  TestAppCheckListener() : num_token_changes_(0) {}
+  ~TestAppCheckListener() override {}
+
+  void OnAppCheckTokenChanged(
+      const firebase::app_check::AppCheckToken& token) override {
+    last_token_ = token;
+    num_token_changes_ += 1;
+  }
+
+  int num_token_changes_;
+  firebase::app_check::AppCheckToken last_token_;
+};
+
 // Initialization flow looks like this:
 //  - For each test:
 //    - Optionally initialize App Check.
@@ -133,7 +149,14 @@ void FirebaseAppCheckTest::InitializeAppCheckWithDebug() {
       firebase::app_check::DebugAppCheckProviderFactory::GetInstance());
 }
 
-void FirebaseAppCheckTest::TerminateAppCheck() {}
+void FirebaseAppCheckTest::TerminateAppCheck() {
+  ::firebase::app_check::AppCheck* app_check =
+      ::firebase::app_check::AppCheck::GetInstance(app_);
+  if (app_check) {
+    LogDebug("Shutdown App Check.");
+    delete app_check;
+  }
+}
 
 void FirebaseAppCheckTest::InitializeApp() {
   LogDebug("Initialize Firebase App.");
@@ -178,8 +201,8 @@ void FirebaseAppCheckTest::TearDown() {
   // Teardown all the products
   TerminateDatabase();
   TerminateAuth();
-  TerminateApp();
   TerminateAppCheck();
+  TerminateApp();
   FirebaseTest::TearDown();
 }
 
@@ -380,6 +403,45 @@ TEST_F(FirebaseAppCheckTest, TestGetTokenLastResult) {
             future2.result()->expire_time_millis);
 }
 
+TEST_F(FirebaseAppCheckTest, TestAddTokenChangedListener) {
+  InitializeAppCheckWithDebug();
+  InitializeApp();
+  ::firebase::app_check::AppCheck* app_check =
+      ::firebase::app_check::AppCheck::GetInstance(app_);
+  ASSERT_NE(app_check, nullptr);
+
+  // Create and add a token changed listener.
+  TestAppCheckListener token_changed_listener;
+  app_check->AddAppCheckListener(&token_changed_listener);
+
+  firebase::Future<::firebase::app_check::AppCheckToken> future =
+      app_check->GetAppCheckToken(true);
+  EXPECT_TRUE(WaitForCompletion(future, "GetToken"));
+  ::firebase::app_check::AppCheckToken token = *future.result();
+
+  ASSERT_EQ(token_changed_listener.num_token_changes_, 1);
+  EXPECT_EQ(token_changed_listener.last_token_.token, token.token);
+}
+
+TEST_F(FirebaseAppCheckTest, TestRemoveTokenChangedListener) {
+  InitializeAppCheckWithDebug();
+  InitializeApp();
+  ::firebase::app_check::AppCheck* app_check =
+      ::firebase::app_check::AppCheck::GetInstance(app_);
+  ASSERT_NE(app_check, nullptr);
+
+  // Create, add, and immediately remove a token changed listener.
+  TestAppCheckListener token_changed_listener;
+  app_check->AddAppCheckListener(&token_changed_listener);
+  app_check->RemoveAppCheckListener(&token_changed_listener);
+
+  firebase::Future<::firebase::app_check::AppCheckToken> future =
+      app_check->GetAppCheckToken(true);
+  EXPECT_TRUE(WaitForCompletion(future, "GetToken"));
+
+  ASSERT_EQ(token_changed_listener.num_token_changes_, 0);
+}
+
 TEST_F(FirebaseAppCheckTest, TestSignIn) {
   InitializeAppCheckWithDebug();
   InitializeApp();

app_check/src/include/firebase/app_check.h

@@ -58,6 +58,7 @@ struct AppCheckToken {
 
 /// @brief Base class used to receive messages when AppCheck token changes.
 class AppCheckListener {
+ public:
   virtual ~AppCheckListener() = 0;
   /// This method gets invoked on the UI thread on changes to the token state.
   /// Does not trigger on token expiry.

app_check/src/ios/app_check_ios.h

@@ -26,10 +26,32 @@
 #import "FIRAppCheck.h"
 #endif  // __OBJC__
 
+#ifdef __OBJC__
+// Interacts with the default notification center.
+@interface AppCheckNotificationCenterWrapper : NSObject
+
+- (id)init;
+
+- (void)stopListening;
+
+- (void)addListener:(firebase::app_check::AppCheckListener* _Nonnull)listener;
+
+- (void)removeListener:(firebase::app_check::AppCheckListener* _Nonnull)listener;
+
+- (void)appCheckTokenDidChangeNotification:(NSNotification*)notification;
+
+@end
+#endif  // __OBJC__
+
 namespace firebase {
 namespace app_check {
 namespace internal {
 
+// This defines the class AppCheckNotificationCenterWrapperPointer, which is a
+// C++-compatible wrapper around the AppCheckNotificationCenterWrapper Obj-C
+// class.
+OBJ_C_PTR_WRAPPER(AppCheckNotificationCenterWrapper);
+
 // This defines the class FIRAppCheckPointer, which is a C++-compatible
 // wrapper around the FIRAppCheck Obj-C class.
 OBJ_C_PTR_WRAPPER(FIRAppCheck);
@@ -61,10 +83,16 @@ class AppCheckInternal {
  private:
 #ifdef __OBJC__
   FIRAppCheck* impl() const { return impl_->get(); }
+
+  AppCheckNotificationCenterWrapper* notification_center_wrapper() const {
+    return notification_center_wrapper_->get();
+  }
 #endif  // __OBJC__
 
   UniquePtr<FIRAppCheckPointer> impl_;
 
+  UniquePtr<AppCheckNotificationCenterWrapperPointer> notification_center_wrapper_;
+
   ::firebase::App* app_;
 
   FutureManager future_manager_;

app_check/src/ios/app_check_ios.mm

@@ -15,6 +15,7 @@
 #include "app_check/src/ios/app_check_ios.h"
 
 #import "FIRApp.h"
+#import "FIRAppCheck.h"
 #import "FIRAppCheckProvider.h"
 #import "FIRAppCheckProviderFactory.h"
 #import "FIRAppCheckToken.h"
@@ -91,16 +92,69 @@ - (id)initWithProviderFactory:(firebase::app_check::AppCheckProviderFactory* _No
 
 @end
 
+@implementation AppCheckNotificationCenterWrapper
+
+// A collection of NSValues containing AppCheckListener*
+NSMutableArray* listeners_;
+
+- (id)init {
+  self = [super init];
+  if (self) {
+    listeners_ = [[NSMutableArray alloc] init];
+    [[NSNotificationCenter defaultCenter] addObserver:self
+                                             selector:@selector(appCheckTokenDidChangeNotification:)
+                                                 name:FIRAppCheckAppCheckTokenDidChangeNotification
+                                               object:nil];
+  }
+  return self;
+}
+
+- (void)stopListening {
+  [[NSNotificationCenter defaultCenter] removeObserver:self
+                                                  name:FIRAppCheckAppCheckTokenDidChangeNotification
+                                                object:nil];
+}
+
+- (void)addListener:(firebase::app_check::AppCheckListener* _Nonnull)listener {
+  [listeners_ addObject:[NSValue valueWithPointer:listener]];
+}
+
+- (void)removeListener:(firebase::app_check::AppCheckListener* _Nonnull)listener {
+  [listeners_ removeObject:[NSValue valueWithPointer:listener]];
+}
+
+- (void)appCheckTokenDidChangeNotification:(NSNotification*)notification {
+  NSDictionary* userInfo = notification.userInfo;
+  NSString* app_name = (NSString*)userInfo[kFIRAppCheckAppNameNotificationKey];
+  NSString* token = (NSString*)userInfo[kFIRAppCheckTokenNotificationKey];
+  // TODO(b/263138261): Include expiration time in this app check token.
+  // Note: The notification contains a token string, but does not currently
+  // contain expiration time.
+  firebase::app_check::AppCheckToken cpp_token;
+  cpp_token.token = firebase::util::NSStringToString(token);
+
+  for (NSValue* listener_value in listeners_) {
+    firebase::app_check::AppCheckListener* listener =
+        static_cast<firebase::app_check::AppCheckListener*>(listener_value.pointerValue);
+    listener->OnAppCheckTokenChanged(cpp_token);
+  }
+}
+
+@end
+
 namespace firebase {
 namespace app_check {
 namespace internal {
 
 AppCheckInternal::AppCheckInternal(App* app) : app_(app) {
   future_manager().AllocFutureApi(this, kAppCheckFnCount);
   impl_ = MakeUnique<FIRAppCheckPointer>([FIRAppCheck appCheck]);
+  notification_center_wrapper_ = MakeUnique<AppCheckNotificationCenterWrapperPointer>(
+      [[AppCheckNotificationCenterWrapper alloc] init]);
 }
 
 AppCheckInternal::~AppCheckInternal() {
+  [notification_center_wrapper() stopListening];
   future_manager().ReleaseFutureApi(this);
   app_ = nullptr;
 }
@@ -157,9 +211,13 @@ - (id)initWithProviderFactory:(firebase::app_check::AppCheckProviderFactory* _No
       future()->LastResult(kAppCheckFnGetAppCheckToken));
 }
 
-void AppCheckInternal::AddAppCheckListener(AppCheckListener* listener) {}
+void AppCheckInternal::AddAppCheckListener(AppCheckListener* listener) {
+  [notification_center_wrapper() addListener:listener];
+}
 
-void AppCheckInternal::RemoveAppCheckListener(AppCheckListener* listener) {}
+void AppCheckInternal::RemoveAppCheckListener(AppCheckListener* listener) {
+  [notification_center_wrapper() removeListener:listener];
+}
 
 }  // namespace internal
 }  // namespace app_check