feat(auth, ios): Add support for Facebook Limited Login (#6073)

* feat(auth,ios): Add support for Facebook Limited Login

Add support for Facebook Limited Login by making passing a second argument to
the providers `credential` function optional and handling this later on in the
native code by calling the OAuth provider for Facebook.

Fixes: #5441
Signed-off-by: Martin Mazein <[email protected]>

* tests(auth): Add test case for FB Limited Login

This is just simply testing if the nonce passed to credentials is the nonce we
see in the providers credential object.

Signed-off-by: Martin Mazein <[email protected]>

* docs(auth,ios): Add code snippet for Facebook Limited Login

Signed-off-by: Martin Mazein <[email protected]>

Author: MegaMaddin

docs/auth/social-auth.md

@@ -136,6 +136,47 @@ async function onFacebookButtonPress() {
 }
 ```
 
+### Facebook Limited Login (iOS only)
+
+To use Facebook Limited Login instead of "classic" Facebook Login, the `onFacebookButtonPress` can then be implemented as follows:
+
+```js
+import auth from '@react-native-firebase/auth';
+import { LoginManager, AuthenticationToken } from 'react-native-fbsdk-next';
+import { sha256 } from 'react-native-sha256';
+
+async function onFacebookButtonPress() {
+  // Create a nonce and the corresponding
+  // sha256 hash of the nonce
+  const nonce = '123456';
+  const nonceSha256 = await sha256(nonce);
+  // Attempt login with permissions and limited login
+  const result = await LoginManager.logInWithPermissions(
+    ['public_profile', 'email'],
+    'limited',
+    nonceSha256,
+  );
+
+  if (result.isCancelled) {
+    throw 'User cancelled the login process';
+  }
+
+  // Once signed in, get the users AuthenticationToken
+  const data = await AuthenticationToken.getAuthenticationTokenIOS();
+
+  if (!data) {
+    throw 'Something went wrong obtaining authentication token';
+  }
+
+  // Create a Firebase credential with the AuthenticationToken
+  // and the nonce (Firebase will validates the hash against the nonce)
+  const facebookCredential = auth.FacebookAuthProvider.credential(data.authenticationToken, nonce);
+
+  // Sign-in the user with the credential
+  return auth().signInWithCredential(facebookCredential);
+}
+```
+
 Upon successful sign-in, any [`onAuthStateChanged`](/auth/usage#listening-to-authentication-state) listeners will trigger
 with the new authentication state of the user.
 

packages/auth/e2e/provider.e2e.js

@@ -75,6 +75,17 @@ describe('auth() -> Providers', function () {
       });
     });
 
+    describe('credentialLimitedLogin', function () {
+      it('should return a credential object', function () {
+        const token = '123456';
+        const nonce = '654321';
+        const credential = firebase.auth.FacebookAuthProvider.credential(token, nonce);
+        credential.providerId.should.equal('facebook.com');
+        credential.token.should.equal(token);
+        credential.secret.should.equal(nonce);
+      });
+    });
+
     describe('PROVIDER_ID', function () {
       it('should return facebook.com', function () {
         firebase.auth.FacebookAuthProvider.PROVIDER_ID.should.equal('facebook.com');

packages/auth/ios/RNFBAuth/RNFBAuthModule.m

@@ -953,6 +953,11 @@ - (FIRAuthCredential *)getCredentialForProvider:(NSString *)provider
     credential = credentials[authToken];
   } else if ([provider compare:@"twitter.com" options:NSCaseInsensitiveSearch] == NSOrderedSame) {
     credential = [FIRTwitterAuthProvider credentialWithToken:authToken secret:authTokenSecret];
+  } else if ([provider compare:@"facebook.com" options:NSCaseInsensitiveSearch] == NSOrderedSame &&
+             ![authTokenSecret isEqualToString:@""]) {
+    credential = [FIROAuthProvider credentialWithProviderID:provider
+                                                    IDToken:authToken
+                                                   rawNonce:authTokenSecret];
   } else if ([provider compare:@"facebook.com" options:NSCaseInsensitiveSearch] == NSOrderedSame) {
     credential = [FIRFacebookAuthProvider credentialWithAccessToken:authToken];
   } else if ([provider compare:@"google.com" options:NSCaseInsensitiveSearch] == NSOrderedSame) {

packages/auth/lib/providers/FacebookAuthProvider.js

@@ -26,10 +26,10 @@ export default class FacebookAuthProvider {
     return providerId;
   }
 
-  static credential(token) {
+  static credential(token, secret = '') {
     return {
       token,
-      secret: '',
+      secret,
       providerId,
     };
   }