public abstract class AuthFragment extends Fragment {

    protected Callback callback;

    @BindView(R.id.caption)
    protected VerticalTextView caption;

    @BindView(R.id.root)
    protected ViewGroup parent;

    protected boolean lock;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View root=inflater.inflate(authLayout(),container,false);
        ButterKnife.bind(this,root);
        KeyboardVisibilityEvent.setEventListener(getActivity(), isOpen -> {
            callback.scale(isOpen);
            if(!isOpen){
                clearFocus();
            }
        });
        return root;
    }

    public void setCallback(@NonNull Callback callback) {
        this.callback = callback;
    }

    @LayoutRes
    public abstract int authLayout();
    public abstract void fold();
    public abstract void clearFocus();
    public abstract Transition unfoldTransition();

    @OnClick(R.id.caption)
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public void unfold(){
        if(!lock) {
            Transition transition = unfoldTransition();
            transition.addListener(new TransitionAdapterListener() {
                @Override
                public void onTransitionEnd(Transition transition) {
                    super.onTransitionEnd(transition);
                    caption.setVerticalText(false);
                    caption.setRotation(0);
                    caption.requestLayout();
                }
            });
            TransitionManager.beginDelayedTransition(parent, transition);
            ConstraintLayout.LayoutParams params = getParams();
            params.rightToRight = ConstraintLayout.LayoutParams.PARENT_ID;
            params.leftToLeft = ConstraintLayout.LayoutParams.PARENT_ID;
            params.verticalBias = 0.8f;
            caption.setScaleY(1f);
            caption.setScaleX(1f);
            caption.setRotation(-90);
            caption.setLayoutParams(params);
            callback.show(this);
            lock=true;
        }
    }

    protected ConstraintLayout.LayoutParams getParams(){
        return ConstraintLayout.LayoutParams.class.cast(caption.getLayoutParams());
    }

    interface Callback {
        void show(AuthFragment fragment);
        void scale(boolean hasFocus);
    }

}