@ActivityScope
public class MainPresenter
        //extends BasePresenter<MainPresenter.ViewContract>
        implements Bundleable, Dispatcher {
    //public interface ViewContract
    //        extends Presenter.ViewContract {
    //}

    //@Override
    //protected void initializeView(ViewContract view) {
    //    // doesn't need to do a thing
    //}

    @Inject
    public MainPresenter() {
    }

    private BehaviorRelay<MainState> state = BehaviorRelay.createDefault(MainState.create());

    public Observable<MainState> state() {
        return state.distinctUntilChanged();
    }

    public void setTitle(int title) {
        state.accept(state.getValue().toBuilder().setTitle(title).build());
    }

    public boolean onBackPressed() {
        if(state.getValue().isDrawerOpen()) {
            closeDrawer();
            return true;
        }
        return false;
    }

    public void openDrawer() {
        state.accept(state.getValue().toBuilder().setIsDrawerOpen(true).build());
    }

    public void closeDrawer() {
        state.accept(state.getValue().toBuilder().setIsDrawerOpen(false).build());
    }

    public void toggleDrawer() {
        if(state.getValue().isDrawerOpen()) {
            closeDrawer();
        } else {
            openDrawer();
        }
    }

    // ...

    private void enableLeftDrawer() {
        state.accept(state.getValue().toBuilder().setLeftDrawerEnabled(true).build());
    }

    private void disableLeftDrawer() {
        state.accept(state.getValue().toBuilder().setLeftDrawerEnabled(false).build());
    }

    // ...

    @Override
    public Bundle toBundle() {
        Bundle bundle = BundleFactory.create();
        bundle.putParcelable("state", state.getValue());
        return bundle;
    }

    @Override
    public void fromBundle(@Nullable Bundle bundle) {
        if(bundle != null) {
            state.accept(bundle.getParcelable("state"));
        }
    }
}