Fix potential account linking sign-in failure due to recursive sign-in attempts (#1293)

Signed-off-by: Alex Saveau <[email protected]>

Author: SUPERCILEX

auth/src/main/java/com/firebase/ui/auth/AuthUI.java

@@ -90,7 +90,8 @@
  */
 public final class AuthUI {
 
-    private static final String TAG = "AuthUI";
+    @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
+    public static final String TAG = "AuthUI";
 
     @StringDef({
                        EmailAuthProvider.PROVIDER_ID,

auth/src/main/java/com/firebase/ui/auth/ui/idp/AuthMethodPickerActivity.java

@@ -117,7 +117,9 @@ private void populateIdpList(List<IdpConfig> providerConfigs,
         for (IdpConfig idpConfig : providerConfigs) {
             final ProviderSignInBase<?> provider;
             @LayoutRes int buttonLayout;
-            switch (idpConfig.getProviderId()) {
+
+            final String providerId = idpConfig.getProviderId();
+            switch (providerId) {
                 case GoogleAuthProvider.PROVIDER_ID:
                     GoogleSignInHandler google = supplier.get(GoogleSignInHandler.class);
                     google.init(new GoogleSignInHandler.Params(idpConfig));
@@ -154,7 +156,7 @@ private void populateIdpList(List<IdpConfig> providerConfigs,
                     buttonLayout = R.layout.fui_provider_button_phone;
                     break;
                 default:
-                    throw new IllegalStateException("Unknown provider: " + idpConfig.getProviderId());
+                    throw new IllegalStateException("Unknown provider: " + providerId);
             }
             mProviders.add(provider);
 
@@ -175,7 +177,12 @@ private void handleResponse(@NonNull IdpResponse response) {
                         // We have no idea what provider this error stemmed from so just forward
                         // this along to the handler.
                         handler.startSignIn(response);
-                    } else if (AuthUI.SOCIAL_PROVIDERS.contains(response.getProviderType())) {
+                    } else if (AuthUI.SOCIAL_PROVIDERS.contains(providerId)) {
+                        // Don't use the response's provider since it can be different than the one
+                        // that launched the sign-in attempt. Ex: the email flow is started, but
+                        // ends up turning into a Google sign-in because that account already
+                        // existed. In the previous example, an extra sign-in would incorrectly
+                        // started.
                         handler.startSignIn(response);
                     } else {
                         // Email or phone: the credentials should have already been saved so simply

auth/src/main/java/com/firebase/ui/auth/viewmodel/ResourceObserver.java

@@ -4,7 +4,9 @@
 import android.support.annotation.NonNull;
 import android.support.annotation.RestrictTo;
 import android.support.annotation.StringRes;
+import android.util.Log;
 
+import com.firebase.ui.auth.AuthUI;
 import com.firebase.ui.auth.data.model.Resource;
 import com.firebase.ui.auth.data.model.State;
 import com.firebase.ui.auth.ui.FragmentBase;
@@ -51,7 +53,10 @@ public final void onChanged(Resource<T> resource) {
             } else {
                 unhandled = FlowUtils.unhandled(mFragment, e);
             }
-            if (unhandled) { onFailure(e); }
+            if (unhandled) {
+                Log.e(AuthUI.TAG, "A sign-in error occurred.", e);
+                onFailure(e);
+            }
         }
     }