Custom login fragment example

public class JwtAuthManagerJava implements AuthLoginManager {

    private static final String NETWORK_NAME = "YOUR_NETWORK_NAME";
    private String currentEmail = null;
    private ObservableCallback<Credential> observableCallback;

    @Override
    public Observable<Credential> login(final Context context) {
        observableCallback = new ObservableCallback<Credential>();

        ActivityUtil.getAppCompatActivity(context).
                getSupportFragmentManager().
                beginTransaction().
                setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_in).
                addToBackStack("LOGIN").
                replace(android.R.id.content, new CustomLoginFragment()).
                commit();

        return observableCallback.asObservable();
    }

    public ObservableCallback<Credential> getObservable(){
        return observableCallback;
    }

    @Override
    public Observable<SimpleUser> register(Context context, @Nullable String email) {
        return Observable.just(SimpleUser.Builder.init("FirstName", "LastName", currentEmail).create());
    }

    @Override
    public Credential refreshToken(Context context) {
        if (currentEmail == null) {
            VouchrSDK.userManager().logout();
            return null;
        } else {
            return new Credential(NETWORK_NAME, getJWT(currentEmail));
        }
    }

    public void setEmail(String email){
        currentEmail = email;
    }

    @Override
    public void logout(Context context) {

    }

    @Override
    public LoginInfo getNetworkInfo() {
        return new LoginInfo(NETWORK_NAME, false, "Voucher SDK JWT Login");
    }

    // CRITICAL: for production uses, jwt must be created/signed by partner login service, not created locally and should be encrypted
    // If you are using this local JWT for testing, select your application, then go to Dashboard / Developer / Authentication and set the authentication's Signature Type to NONE
    private String getJWT(String username) {
            JSONObject header = new JSONObject();
        try {
            header.put("alg", "none");
            header.put("type", "jwt");

            JSONObject claims = new JSONObject();
            claims.put("sub", username);
            claims.put("email", username);
            claims.put("email_verified", true);

            StringBuilder sb = new StringBuilder();
            sb.append(new String((toBase64(header.toString(), Base64.URL_SAFE)), Charset.defaultCharset()));
            sb.append(".");
            sb.append(new String((toBase64(claims.toString(), Base64.URL_SAFE)), Charset.defaultCharset()));
            return sb.toString();
        } catch (JSONException e) {
            e.printStackTrace();
            return null;
        }
    }

    private byte[] toBase64(String string, int flags) {
        byte[] bytes = string.getBytes(Charset.defaultCharset());
        return Base64.encode(bytes, flags);
    }
}

public class CustomLoginFragmentJava extends Fragment {

    @BindView(R.id.btnLogin)
    protected VouchrButton btnLogin;
    @BindView(R.id.close_btn)
    protected VouchrButton btnClose;
    @BindView(R.id.inputPassword)
    protected SensitiveInfoEditText inputPassword;
    @BindView(R.id.inputEmail)
    protected SensitiveInfoEditText inputEmail;
    private String networkName = "JWT_TEST";
    private JwtAuthManager jwt;
    private Boolean logged = false;


    public CustomLoginFragmentJava() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        jwt = (JwtAuthManager) Engine.userManager().getAuthManagerForNetworkName(networkName);
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        btnLogin.setOnClickListener((View v) -> {
            login();
        });
        btnClose.setOnClickListener((View v) -> {
            getActivity().getSupportFragmentManager().popBackStack("LOGIN", FragmentManager.POP_BACK_STACK_INCLUSIVE);
        });
        inputPassword.setTransformationMethod(new PasswordTransformationMethod());
    }

    @Override
    public void onDestroy() {
        if (!logged) {
            ObservableCallback<Credential> observableCallback = jwt.getObservable();
            observableCallback.onError(new Exception("Canceled"));
        }
        super.onDestroy();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_custom_login, null);
        ButterKnife.bind(this, view);
        return view;
    }

    public void login() {
        ObservableCallback<Credential> observableCallback = jwt.getObservable();
        String email = inputEmail.getText().toString();
        String password = inputPassword.getText().toString();

        if (email.isEmpty()) {
            Toast.makeText(getContext(), "Need to enter info", Toast.LENGTH_LONG).show();
            return;
        } else {
            Credential credential = new Credential(networkName, getJWT(email.toLowerCase()));
            jwt.setEmail(email);
            observableCallback.onSuccess(credential);
            logged = true;
            getActivity().getSupportFragmentManager().popBackStack("LOGIN", FragmentManager.POP_BACK_STACK_INCLUSIVE);
        }
    }

    // CRITICAL: for production uses, jwt must be created/signed by partner login service, not created locally and should be encrypted
    // If you are using this local JWT for testing, select your application, then go to Dashboard / Developer / Authentication and set the authentication's Signature Type to NONE
    private String getJWT(String username) {
        JSONObject header = new JSONObject();
        try {
            header.put("alg", "none");
            header.put("type", "jwt");

            JSONObject claims = new JSONObject();
            claims.put("sub", username);
            claims.put("email", username);
            claims.put("email_verified", true);

            StringBuilder sb = new StringBuilder();
            sb.append(new String((toBase64(header.toString(), Base64.URL_SAFE)), Charset.defaultCharset()));
            sb.append(".");
            sb.append(new String((toBase64(claims.toString(), Base64.URL_SAFE)), Charset.defaultCharset()));
            return sb.toString();
        } catch (JSONException e) {
            e.printStackTrace();
            return null;
        }
    }

    private byte[] toBase64(String string, int flags) {
        byte[] bytes = string.getBytes(Charset.defaultCharset());
        return Base64.encode(bytes, flags);
    }
}