@Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {

        FragmentTransaction ft = fm.beginTransaction();
        Fragment currentFrag = fm.findFragmentById(R.id.container);

        int id = item.getItemId();
        switch (id) {
            case R.id.trains: {
                if (currentFrag == trainListFrag) {
                    ((TrainListFragment) trainListFrag).scrollToTop();
                    break;
                }
                ft.replace(R.id.container, trainListFrag);
                arrangeFragmentHistory(trainListFrag);
                break;
            }
            case R.id.brands: {
                if (currentFrag == brandListFrag) {
                    break;
                }
                ft.replace(R.id.container, brandListFrag);
                arrangeFragmentHistory(brandListFrag);
                break;
            }
            case R.id.categories: {
                if (currentFrag == categoryListFrag) {
                    break;
                }
                ft.replace(R.id.container, categoryListFrag);
                arrangeFragmentHistory(categoryListFrag);
                break;
            }
        }
        ft.setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
                .commit();
        fm.executePendingTransactions();
        onFragmentHistoryChanged();
        return true;
    }

    private void arrangeFragmentHistory(Fragment fragment) {
        fragmentHistory.removeFirstOccurrence(fragment);
        fragmentHistory.add(fragment);
    }

    private void goBackToPreviousFragment() {
        if (fragmentHistory.size() > 1) {
            fragmentHistory.removeLast();
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.container, fragmentHistory.getLast())
                    .setCustomAnimations(android.R.animator.fade_in, android.R.animator.fade_out)
                    .commit();
            fm.executePendingTransactions();
            onFragmentHistoryChanged();
        } else {
            super.onBackPressed();
        }
    }

    private void onFragmentHistoryChanged() {
        clearFocusAndHideKeyboard();
        Fragment currentFrag = getSupportFragmentManager().findFragmentById(R.id.container);
        setMenuItemChecked(currentFrag);
        hideOrShowBottomNavigation(currentFrag);
    }