Authorization Interceptor

AuthInterceptor.java

@Singleton
public final class AuthInterceptor implements Interceptor {

    private final Prefs prefs;

    @Inject
    public AuthInterceptor(Prefs prefs) {
        this.prefs = prefs;
    }

    @Override
    public Response intercept(Chain chain) throws IOException {
        // Add authorization header to each request if Access Token exists on device
        Request request = chain.request();
        final String accessToken = this.prefs.getAccessToken();
        if (accessToken != null) {
            final Headers headers = request.headers()
                    .newBuilder()
                    .add(Constants.ACCESS_TOKEN_HEADER, accessToken)
                    .build();
            request = request.newBuilder().headers(headers).build();
        }

        // Store obtained Access Token and Refresh Token if response contains them.
        // Responses which serve new tokens: /signin, /signup, /auth_via_facebook, /session
        final Response response = chain.proceed(request);
        final String newAccessToken = response.headers().get(Constants.ACCESS_TOKEN_HEADER);
        final String newRefreshToken = response.headers().get(Constants.REFRESH_TOKEN_HEADER);
        final Date refreshTokenExpired = response.headers().getDate(Constants.REFRESH_TOKEN_EXPIRED_HEADER);
        if (newAccessToken != null) {
            prefs.setAccessToken(newAccessToken);
        }
        if (newRefreshToken != null) {
            prefs.setRefreshToken(newRefreshToken);
        }
        return response;
    }

}