Is it possible to add a Line login button to FirebaseUI so that it will be displayed in addition to FB, Google, email, and phone login options?

Question

Looking to add a Line login button while at the same time using FirebaseUI. Is it even possible or are we limited to the provider auth providers? If possible, how would I edit the below code to add the custom button?

AuthUI.IdpConfig phoneConfigWithDefaultNumber = new AuthUI.IdpConfig.PhoneBuilder()
                        .setDefaultCountryIso("th")
                        .build();

                startActivityForResult(
                        AuthUI.getInstance()
                                .createSignInIntentBuilder()
                                .setTheme(R.style.LoginTheme)
                                .setLogo(R.drawable.spurs)
                                .setAvailableProviders(Arrays.asList(
                                        new AuthUI.IdpConfig.GoogleBuilder().build(),
                                        new AuthUI.IdpConfig.FacebookBuilder().build(),
                                        new AuthUI.IdpConfig.EmailBuilder().build(),
                                        phoneConfigWithDefaultNumber))
                                .build(),
                        RC_SIGN_IN);

Answer 1

LINE is currently not a built-in provider of Firebase Authentication, so the only way to use it is to implement it as a custom provider. There is a good example of using LINE as an authentication provider for Firebase in the functions-samples repo.

But adding a custom auth provider is currently not a documented extension point of FirebaseUI. So that means you'd have to form FirebaseUI, and modify the code to allow LINE.

Allowing to add your own provider to FirebaseUI is actually an interesting use-case though, so I'd recommend filing a feature request on the repo to make this possible.