firebase · samtstern · Apr 17, 2018 · Mar 25, 2018 · Mar 25, 2018 · Mar 25, 2018
diff --git a/app/src/main/java/com/firebase/uidemo/auth/AuthUiActivity.java b/app/src/main/java/com/firebase/uidemo/auth/AuthUiActivity.java
@@ -18,6 +18,7 @@
 import android.content.Intent;
 import android.os.Bundle;
 import android.support.annotation.DrawableRes;
+import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 import android.support.annotation.StringRes;
 import android.support.annotation.StyleRes;
@@ -26,7 +27,6 @@
 import android.support.v7.app.AppCompatDelegate;
 import android.util.Log;
 import android.view.View;
-import android.widget.Button;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
 import android.widget.CompoundButton.OnCheckedChangeListener;
@@ -39,6 +39,9 @@
 import com.firebase.ui.auth.IdpResponse;
 import com.firebase.uidemo.R;
 import com.google.android.gms.common.Scopes;
+import com.google.android.gms.tasks.OnCompleteListener;
+import com.google.android.gms.tasks.Task;
+import com.google.firebase.auth.AuthResult;
 import com.google.firebase.auth.FirebaseAuth;
 
 import java.util.ArrayList;
@@ -60,7 +63,6 @@ public class AuthUiActivity extends AppCompatActivity {
     private static final int RC_SIGN_IN = 100;
 
     @BindView(R.id.root) View mRootView;
-    @BindView(R.id.sign_in) Button mSignIn;
 
     @BindView(R.id.google_provider) CheckBox mUseGoogleProvider;
     @BindView(R.id.facebook_provider) CheckBox mUseFacebookProvider;
@@ -166,6 +168,21 @@ public void signIn(View view) {
                 RC_SIGN_IN);
     }
 
+    @OnClick(R.id.sign_in_silent)
+    public void silentSignIn(View view) {
+        AuthUI.getInstance().silentSignIn(this, getSelectedProviders())
+                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
+                    @Override
+                    public void onComplete(@NonNull Task<AuthResult> task) {
+                        if (task.isSuccessful()) {
+                            startSignedInActivity(null);
+                        } else {
+                            showSnackbar(R.string.sign_in_failed);
+                        }
+                    }
+                });
+    }
+
     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
         super.onActivityResult(requestCode, resultCode, data);

diff --git a/app/src/main/res/layout/auth_ui_layout.xml b/app/src/main/res/layout/auth_ui_layout.xml
@@ -35,9 +35,18 @@
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_gravity="center"
-                android:layout_margin="16dp"
+                android:layout_marginTop="16dp"
                 android:text="@string/sign_in_start" />
 
+            <Button
+                android:id="@+id/sign_in_silent"
+                style="@style/Widget.AppCompat.Button.Colored"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_gravity="center"
+                android:layout_marginBottom="16dp"
+                android:text="@string/sign_in_silent" />
+
             <TextView
                 style="@style/Base.TextAppearance.AppCompat.Subhead"
                 android:layout_width="wrap_content"

diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
@@ -17,6 +17,7 @@
     <!-- Auth UI -->
     <string name="launch_title">FirebaseUI Auth Demo</string>
     <string name="sign_in_start">Start</string>
+    <string name="sign_in_silent">Sign in silently</string>
 
     <string name="providers_header">Auth providers</string>
     <string name="providers_google">Google</string>
@@ -72,6 +73,7 @@
     <string name="sign_out">Sign out</string>
     <string name="delete_account_label">Delete account</string>
 
+    <string name="sign_in_failed">Sign in failed</string>
     <string name="sign_out_failed">Sign out failed</string>
     <string name="delete_account_failed">Delete account failed</string>
 

diff --git a/auth/README.md b/auth/README.md
@@ -33,8 +33,9 @@ and [Web](https://github.com/firebase/firebaseui-web/).
 1. [Configuration](#configuration)
    1. [Provider config](#identity-provider-configuration)
 1. [Usage instructions](#using-firebaseui-for-authentication)
-   1. [Sign in](#sign-in)
+   1. [AuthUI sign-in](#authui-sign-in)
    1. [Handling responses](#handling-the-sign-in-response)
+   1. [Silent sign-in](#silent-sign-in)
    1. [Sign out](#sign-out)
    1. [Account deletion](#deleting-accounts)
    1. [Auth flow chart](#authentication-flow-chart)
@@ -169,7 +170,7 @@ If an alternative app instance is required, call
 `AuthUI.getInstance(app)` instead, passing the appropriate `FirebaseApp`
 instance.
 
-### Sign in
+### AuthUI sign-in
 
 If a user is not currently signed in, as can be determined by checking
 `auth.getCurrentUser() != null` (where `auth` is the `FirebaseAuth` instance
@@ -352,7 +353,7 @@ protected void onActivityResult(int requestCode, int resultCode, Intent data) {
                 showSnackbar(R.string.no_internet_connection);
                 return;
             }
-        
+
             showSnackbar(R.string.unknown_error);
             Log.e(TAG, "Sign-in error: ", response.getError());
         }
@@ -401,6 +402,40 @@ if (metadata.getCreationTimestamp() == metadata.getLastSignInTimestamp()) {
 }
 ```
 
+### Silent sign-in
+
+If a user is not currently signed in, then a silent sign-in process can be started first before
+displaying any UI to provide a seamless experience. Silent sign-in uses saved Smart Lock credentials
+and returns a successful `Task` only if the user has been fully signed in with Firebase.
+
+Here's an example of how you could use silent sign-in paired with Firebase anonymous sign-in to get
+your users up and running as fast as possible:
+
+```java
+List<IdpConfig> providers = getSelectedProviders();
+AuthUI.getInstance().silentSignIn(this, providers)
+        .continueWithTask(this, new Continuation<AuthResult, Task<AuthResult>>() {
+    @Override
+    public Task<AuthResult> then(@NonNull Task<AuthResult> task) {
+        if (task.isSuccessful()) {
+            return task;
+        } else {
+            // Ignore any exceptions since we don't care about credential fetch errors.
+            return FirebaseAuth.getInstance().signInAnonymously();
+        }
+    }
+}).addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
+    @Override
+    public void onComplete(@NonNull Task<AuthResult> task) {
+        if (task.isSuccessful()) {
+            // Signed in! Start loading data
+        } else {
+            // Uh oh, show error message
+        }
+    }
+});
+```
+
 ### Sign out
 
 With the integrations provided by AuthUI, signing out a user is a multi-stage process:

diff --git a/auth/src/main/java/com/firebase/ui/auth/AuthUI.java b/auth/src/main/java/com/firebase/ui/auth/AuthUI.java
@@ -41,8 +41,11 @@
 import com.firebase.ui.auth.util.data.PhoneNumberUtils;
 import com.firebase.ui.auth.util.data.ProviderUtils;
 import com.google.android.gms.auth.api.credentials.Credential;
+import com.google.android.gms.auth.api.credentials.CredentialRequest;
+import com.google.android.gms.auth.api.credentials.CredentialRequestResponse;
 import com.google.android.gms.auth.api.credentials.CredentialsClient;
 import com.google.android.gms.auth.api.signin.GoogleSignIn;
+import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
 import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
 import com.google.android.gms.common.api.ApiException;
 import com.google.android.gms.common.api.CommonStatusCodes;
@@ -51,6 +54,8 @@
 import com.google.android.gms.tasks.Task;
 import com.google.android.gms.tasks.Tasks;
 import com.google.firebase.FirebaseApp;
+import com.google.firebase.auth.AuthCredential;
+import com.google.firebase.auth.AuthResult;
 import com.google.firebase.auth.EmailAuthProvider;
 import com.google.firebase.auth.FacebookAuthProvider;
 import com.google.firebase.auth.FirebaseAuth;
@@ -267,6 +272,85 @@ public static int getDefaultTheme() {
         return R.style.FirebaseUI;
     }
 
+    /**
+     * Signs the user in without any UI if possible. If this operation fails, you can safely start a
+     * UI-based sign-in flow knowing it is required.
+     *
+     * @param context        requesting the user be signed in
+     * @param desiredConfigs to use for silent sign in. Only Google and email are currently
+     *                       supported, the rest will be ignored.
+     * @return a task which indicates whether or not the user was successfully signed in.
+     */
+    @NonNull
+    public Task<AuthResult> silentSignIn(@NonNull Context context,
+                                         @NonNull List<IdpConfig> configs) {
+        if (mAuth.getCurrentUser() != null) {
+            throw new IllegalArgumentException("User already signed in!");
+        }
+
+        final Context appContext = context.getApplicationContext();
+        final IdpConfig google =
+                ProviderUtils.getConfigFromIdps(configs, GoogleAuthProvider.PROVIDER_ID);
+        final IdpConfig email =
+                ProviderUtils.getConfigFromIdps(configs, EmailAuthProvider.PROVIDER_ID);
+
+        if (google == null && email == null) {
+            throw new IllegalArgumentException("No supported providers were supplied. " +
+                    "Add either Google or email support.");
+        }
+
+        final GoogleSignInOptions googleOptions;
+        if (google == null) {
+            googleOptions = null;
+        } else {
+            GoogleSignInAccount last = GoogleSignIn.getLastSignedInAccount(appContext);
+            if (last != null && last.getIdToken() != null) {
+                return mAuth.signInWithCredential(GoogleAuthProvider.getCredential(
+                        last.getIdToken(), null));
+            }
+
+            googleOptions = google.getParams()
+                    .getParcelable(ExtraConstants.GOOGLE_SIGN_IN_OPTIONS);
+        }
+
+        return GoogleApiUtils.getCredentialsClient(context)
+                .request(new CredentialRequest.Builder()
+                        // We can support both email and Google at the same time here because they
+                        // are mutually exclusive. If a user signs in with Google, their email
+                        // account will automatically be upgraded (a.k.a. replaced) with the Google
+                        // one, meaning Smart Lock won't have to show the picker UI.
+                        .setPasswordLoginSupported(email != null)
+                        .setAccountTypes(google == null ? null :
+                                ProviderUtils.providerIdToAccountType(GoogleAuthProvider.PROVIDER_ID))
+                        .build())
+                .continueWithTask(new Continuation<CredentialRequestResponse, Task<AuthResult>>() {
+                    @Override
+                    public Task<AuthResult> then(@NonNull Task<CredentialRequestResponse> task) {
+                        Credential credential = task.getResult().getCredential();
+                        String email = credential.getId();
+                        String password = credential.getPassword();
+
+                        if (TextUtils.isEmpty(password)) {
+                            return GoogleSignIn.getClient(appContext,
+                                    new GoogleSignInOptions.Builder(googleOptions)
+                                            .setAccountName(email)
+                                            .build())
+                                    .silentSignIn()
+                                    .continueWithTask(new Continuation<GoogleSignInAccount, Task<AuthResult>>() {
+                                        @Override
+                                        public Task<AuthResult> then(@NonNull Task<GoogleSignInAccount> task) {
+                                            AuthCredential authCredential = GoogleAuthProvider.getCredential(
+                                                    task.getResult().getIdToken(), null);
+                                            return mAuth.signInWithCredential(authCredential);
+                                        }
+                                    });
+                        } else {
+                            return mAuth.signInWithEmailAndPassword(email, password);
+                        }
+                    }
+                });
+    }
+
     /**
      * Signs the current user out, if one is signed in.
      *