fix(auth, android): return credential for signin if phone auth has link collision (#7793)

* Fix Android phone sign in not returning authCredential

You can now upgrade anonymous users using phone auth on Android. Credit to @Shaninnik.

* Apply suggestions from code review

* style(lint): `yarn lint:android`

cleaning things up after merging in suggestions

* fix(auth, android): if no credential in collision exception, avoid accessing it

---------

Co-authored-by: Mike Hardy <[email protected]>

Author: joaqo

packages/auth/android/src/main/java/io/invertase/firebase/auth/ReactNativeFirebaseAuthModule.java

@@ -49,6 +49,7 @@
 import com.google.firebase.auth.FirebaseAuthMultiFactorException;
 import com.google.firebase.auth.FirebaseAuthProvider;
 import com.google.firebase.auth.FirebaseAuthSettings;
+import com.google.firebase.auth.FirebaseAuthUserCollisionException;
 import com.google.firebase.auth.FirebaseUser;
 import com.google.firebase.auth.FirebaseUserMetadata;
 import com.google.firebase.auth.GetTokenResult;
@@ -107,6 +108,10 @@ class ReactNativeFirebaseAuthModule extends ReactNativeFirebaseModule {
   private final HashMap<String, MultiFactorResolver> mCachedResolvers = new HashMap<>();
   private final HashMap<String, MultiFactorSession> mMultiFactorSessions = new HashMap<>();
 
+  // storage for anonymous phone auth credentials, used for linkWithCredentials
+  // https://github.com/invertase/react-native-firebase/issues/4911
+  private HashMap<String, AuthCredential> credentials = new HashMap<>();
+
   ReactNativeFirebaseAuthModule(ReactApplicationContext reactContext) {
     super(reactContext, TAG);
   }
@@ -914,9 +919,8 @@ private void signInWithProvider(String appName, ReadableMap provider, final Prom
       return;
     }
 
-    OAuthProvider.Builder builder = OAuthProvider.newBuilder(
-        provider.getString("providerId"),
-        firebaseAuth);
+    OAuthProvider.Builder builder =
+        OAuthProvider.newBuilder(provider.getString("providerId"), firebaseAuth);
     // Add scopes if present
     if (provider.hasKey("scopes")) {
       ReadableArray scopes = provider.getArray("scopes");
@@ -1613,6 +1617,17 @@ private void linkWithCredential(
                     promiseWithAuthResult(task.getResult(), promise);
                   } else {
                     Exception exception = task.getException();
+                    if (exception instanceof FirebaseAuthUserCollisionException collEx) {
+                      AuthCredential updatedCredential = collEx.getUpdatedCredential();
+                      Log.d(TAG, "link:onComplete:collisionFailure", collEx);
+                      // If we have a credential in the error, we can return it, otherwise fall
+                      // through
+                      if (updatedCredential != null) {
+                        Log.d(TAG, "link:onComplete:collisionFailure had credential", collEx);
+                        promiseRejectLinkAuthException(promise, collEx, updatedCredential);
+                        return;
+                      }
+                    }
                     Log.e(TAG, "link:onComplete:failure", exception);
                     promiseRejectAuthException(promise, exception);
                   }
@@ -1650,9 +1665,8 @@ private void linkWithProvider(String appName, ReadableMap provider, final Promis
       return;
     }
 
-    OAuthProvider.Builder builder = OAuthProvider.newBuilder(
-        provider.getString("providerId"),
-        firebaseAuth);
+    OAuthProvider.Builder builder =
+        OAuthProvider.newBuilder(provider.getString("providerId"), firebaseAuth);
     // Add scopes if present
     if (provider.hasKey("scopes")) {
       ReadableArray scopes = provider.getArray("scopes");
@@ -1795,9 +1809,8 @@ private void reauthenticateWithProvider(
       return;
     }
 
-    OAuthProvider.Builder builder = OAuthProvider.newBuilder(
-        provider.getString("providerId"),
-        firebaseAuth);
+    OAuthProvider.Builder builder =
+        OAuthProvider.newBuilder(provider.getString("providerId"), firebaseAuth);
     // Add scopes if present
     if (provider.hasKey("scopes")) {
       ReadableArray scopes = provider.getArray("scopes");
@@ -1855,6 +1868,9 @@ private AuthCredential getCredentialForProvider(
     if (provider.startsWith("oidc.")) {
       return OAuthProvider.newCredentialBuilder(provider).setIdToken(authToken).build();
     }
+    if (credentials.containsKey(authToken) && credentials.get(authToken) != null) {
+      return credentials.get(authToken);
+    }
 
     switch (provider) {
       case "facebook.com":
@@ -2217,6 +2233,36 @@ private void promiseRejectAuthException(Promise promise, Exception exception) {
         promise, error.getString("code"), error.getString("message"), resolverAsMap);
   }
 
+  /**
+   * promiseRejectLinkAuthException
+   *
+   * @param promise
+   * @param exception
+   * @param authCredential
+   */
+  private void promiseRejectLinkAuthException(
+      @NonNull Promise promise,
+      @NonNull Exception exception,
+      @NonNull AuthCredential authCredential) {
+    WritableMap error = getJSError(exception);
+    String authHashCode = String.valueOf(authCredential.hashCode());
+
+    WritableMap authCredentialsMap = Arguments.createMap();
+    authCredentialsMap.putString("providerId", authCredential.getProvider());
+    authCredentialsMap.putString("token", authHashCode);
+    authCredentialsMap.putString("secret", null);
+
+    // Temporarily store the non-serializable credential for later
+    credentials.put(authHashCode, authCredential);
+
+    WritableMap userInfoMap = Arguments.createMap();
+    userInfoMap.putString("code", error.getString("code"));
+    userInfoMap.putString("message", error.getString("message"));
+    userInfoMap.putMap("authCredential", authCredentialsMap);
+
+    promise.reject(error.getString("code"), error.getString("message"), userInfoMap);
+  }
+
   /**
    * getJSError
    *