feat(app-check, android): Implement app check token change listener

packages/app-check/android/src/main/java/io/invertase/firebase/appcheck/ReactNativeFirebaseAppCheckModule.java

@@ -28,11 +28,19 @@
 import io.invertase.firebase.common.ReactNativeFirebaseMeta;
 import io.invertase.firebase.common.ReactNativeFirebaseModule;
 import io.invertase.firebase.common.ReactNativeFirebasePreferences;
+import io.invertase.firebase.common.ReactNativeFirebaseEvent;
+import io.invertase.firebase.common.ReactNativeFirebaseEventEmitter;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.Map;
 
 public class ReactNativeFirebaseAppCheckModule extends ReactNativeFirebaseModule {
   private static final String TAG = "AppCheck";
   private static final String LOGTAG = "RNFBAppCheck";
   private static final String KEY_APPCHECK_TOKEN_REFRESH_ENABLED = "app_check_token_auto_refresh";
+
+  private static HashMap<String, FirebaseAppCheck.AppCheckListener> mAppCheckListeners = new HashMap<>();
+
   ReactNativeFirebaseAppCheckProviderFactory providerFactory =
       new ReactNativeFirebaseAppCheckProviderFactory();
 
@@ -90,6 +98,24 @@ private boolean isAppDebuggable() throws Exception {
     firebaseAppCheck.setTokenAutoRefreshEnabled(isAppCheckTokenRefreshEnabled());
   }
 
+  @Override
+  public void onCatalystInstanceDestroy() {
+    super.onCatalystInstanceDestroy();
+    Log.d(TAG, "instance-destroyed");
+
+    Iterator appCheckListenerIterator = mAppCheckListeners.entrySet().iterator();
+
+    while (appCheckListenerIterator.hasNext()) {
+      Map.Entry pair = (Map.Entry) appCheckListenerIterator.next();
+      String appName = (String) pair.getKey();
+      FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
+      FirebaseAppCheck firebaseAppCheck = FirebaseAppCheck.getInstance(firebaseApp);
+      FirebaseAppCheck.AppCheckListener mAppCheckListener = (FirebaseAppCheck.AppCheckListener) pair.getValue();
+      firebaseAppCheck.removeAppCheckListener(mAppCheckListener);
+      appCheckListenerIterator.remove();
+    }
+  }
+
   @ReactMethod
   public void configureProvider(
       String appName, String providerName, String debugToken, Promise promise) {
@@ -177,4 +203,45 @@ public void getToken(String appName, boolean forceRefresh, Promise promise) {
               }
             });
   }
+
+  /** Add a new token change listener - if one doesn't exist already */
+  @ReactMethod
+  public void addAppCheckListener(final String appName) {
+    Log.d(TAG, "addAppCheckListener " + appName);
+
+    FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
+    FirebaseAppCheck firebaseAppCheck = FirebaseAppCheck.getInstance(firebaseApp);
+
+    if (mAppCheckListeners.get(appName) == null) {
+      FirebaseAppCheck.AppCheckListener newAppCheckListener = appCheckToken -> {
+        WritableMap eventBody = Arguments.createMap();
+        eventBody.putString("appName", appName); // for js side distribution
+        eventBody.putString("token", appCheckToken.getToken());
+        eventBody.putDouble("expireTimeMillis", appCheckToken.getExpireTimeMillis());
+
+        ReactNativeFirebaseEventEmitter emitter = ReactNativeFirebaseEventEmitter.getSharedInstance();
+        ReactNativeFirebaseEvent event = new ReactNativeFirebaseEvent("appCheck_token_changed", eventBody, appName);
+        emitter.sendEvent(event);
+      };
+
+      firebaseAppCheck.addAppCheckListener(newAppCheckListener);
+      mAppCheckListeners.put(appName, newAppCheckListener);
+    }
+  }
+
+  /** Removes the current token change listener */
+  @ReactMethod
+  public void removeAppCheckListener(String appName) {
+    Log.d(TAG, "removeAppCheckListener " + appName);
+
+    FirebaseApp firebaseApp = FirebaseApp.getInstance(appName);
+    FirebaseAppCheck firebaseAppCheck = FirebaseAppCheck.getInstance(firebaseApp);
+
+    FirebaseAppCheck.AppCheckListener mAppCheckListener = mAppCheckListeners.get(appName);
+
+    if (mAppCheckListener != null) {
+      firebaseAppCheck.removeAppCheckListener(mAppCheckListener);
+      mAppCheckListeners.remove(appName);
+    }
+  }
 }

packages/app-check/lib/index.d.ts

@@ -88,6 +88,18 @@ export namespace FirebaseAppCheckTypes {
     isTokenAutoRefreshEnabled?: boolean;
   }
 
+  export type NextFn<T> = (value: T) => void;
+  export type ErrorFn = (error: Error) => void;
+  export type CompleteFn = () => void;
+
+  export interface Observer<T> {
+    next: NextFn<T>;
+    error: ErrorFn;
+    complete: CompleteFn;
+  }
+
+  export type PartialObserver<T> = Partial<Observer<T>>;
+
   export interface ReactNativeFirebaseAppCheckProviderOptions {
     /**
      * debug token to use, if any. Defaults to undefined, pre-configure tokens in firebase web console if needed
@@ -165,6 +177,10 @@ export namespace FirebaseAppCheckTypes {
      */
     readonly expireTimeMillis: number;
   }
+  /**
+   * The result return from `onTokenChanged`
+   */
+  export type AppCheckListenerResult = AppCheckToken & { readonly appName: string };
 
   // eslint-disable-next-line @typescript-eslint/no-empty-interface
   export interface Statics {
@@ -258,12 +274,9 @@ export namespace FirebaseAppCheckTypes {
      *
      * @returns A function that unsubscribes this listener.
      */
-    // TODO there is a great deal of Observer / PartialObserver typing to carry-in
-    // onTokenChanged(observer: PartialObserver<AppCheckTokenResult>): () => void;
+    onTokenChanged(observer: PartialObserver<AppCheckListenerResult>): () => void;
 
     /**
-     * TODO implement token listener for android.
-     *
      * Registers a listener to changes in the token state. There can be more
      * than one listener registered at the same time for one or more
      * App Check instances. The listeners call back on the UI thread whenever
@@ -272,13 +285,19 @@ export namespace FirebaseAppCheckTypes {
      * Token listeners do not exist in the native SDK for iOS, no token change events will be emitted on that platform.
      * This is not yet implemented on Android, no token change events will be emitted until implemented.
      *
+     * NOTE: Although an `onError` callback can be provided, it will
+     * never be called, Android sdk code doesn't provide handling for onError function
+     *
+     * NOTE: Although an `onCompletion` callback can be provided, it will
+     * never be called because the token stream is never-ending.
+     *
      * @returns A function that unsubscribes this listener.
      */
-    // onTokenChanged(
-    //   onNext: (tokenResult: AppCheckTokenResult) => void,
-    //   onError?: (error: Error) => void,
-    //   onCompletion?: () => void,
-    // ): () => void;
+    onTokenChanged(
+      onNext: (tokenResult: AppCheckListenerResult) => void,
+      onError?: (error: Error) => void,
+      onCompletion?: () => void,
+    ): () => void;
   }
 }
 

packages/app-check/lib/index.js

@@ -40,6 +40,16 @@
 const nativeModuleName = 'RNFBAppCheckModule';
 
 class FirebaseAppCheckModule extends FirebaseModule {
+  constructor(...args) {
+    super(...args);
+
+    this.emitter.addListener(this.eventNameForApp('appCheck_token_changed'), event => {
+      this.emitter.emit(this.eventNameForApp('onAppCheckTokenChanged'), event);
+    });
+
+    this._listenerCount = 0;
+  }
+
   getIsTokenRefreshEnabledDefault() {
     // no default to start
     isTokenAutoRefreshEnabled = undefined;
@@ -131,13 +141,40 @@
     }
   }
 
-  onTokenChanged() {
+  _parseListener(listenerOrObserver) {
+    return typeof listenerOrObserver === 'object'
+      ? listenerOrObserver.next.bind(listenerOrObserver)
+      : listenerOrObserver;
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  onTokenChanged(onNextOrObserver, onError, onCompletion) {
     // iOS does not provide any native listening feature
     if (isIOS) {
+      // eslint-disable-next-line no-console
+      console.warn('onTokenChanged is not implemented on IOS, only for Android');
       return () => {};
     }
-    // TODO unimplemented on Android
-    return () => {};
+    const nextFn = this._parseListener(onNextOrObserver);
+    // let errorFn = function () { };
+    // if (onNextOrObserver.error != null) {
+    //   errorFn = onNextOrObserver.error.bind(onNextOrObserver);
+    // }
+    // else if (onError) {
+    //   errorFn = onError;
+    // }
+    const subscription = this.emitter.addListener(
+      this.eventNameForApp('onAppCheckTokenChanged'),
+      nextFn,
+    );
+    if (this._listenerCount === 0) this.native.addAppCheckListener();
+
+    this._listenerCount++;
+    return () => {
+      subscription.remove();
+      this._listenerCount--;
+      if (this._listenerCount === 0) this.native.removeAppCheckListener();
+    };
   }
 }
 
@@ -151,7 +188,7 @@
   version,
   namespace,
   nativeModuleName,
-  nativeEvents: false, // TODO implement ['appcheck-token-changed'],
+  nativeEvents: ['appCheck_token_changed'],
   hasMultiAppSupport: true,
   hasCustomUrlOrRegionSupport: false,
   ModuleClass: FirebaseAppCheckModule,