public class RecyclerViewScrollManager {
    private final PublishRelay<Void> relay;
    private final RecyclerView recyclerView;
    private boolean isLoading = false;
    private int visibleThreshold = 5;
    private int lastVisibleItem;
    private int totalItemCount;
    private RecyclerView.OnScrollListener scrollListener;

    public RecyclerViewScrollManager(RecyclerView recyclerView, int visibleThreshold) {
        this.visibleThreshold = visibleThreshold;
        this.recyclerView = recyclerView;
        relay = PublishRelay.create();
    }

    public PublishRelay<Void> getScrollListener() {
        scrollListener = buildOnScrollListener((LinearLayoutManager) recyclerView.getLayoutManager());
        recyclerView.addOnScrollListener(scrollListener);
        return relay;
    }

    @NonNull
    private RecyclerView.OnScrollListener buildOnScrollListener(final LinearLayoutManager layoutManager) {
        return new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                totalItemCount = layoutManager.getItemCount();
                lastVisibleItem = layoutManager.findLastVisibleItemPosition();
                if (!isLoading && totalItemCount <= (lastVisibleItem + visibleThreshold)) {
                    relay.call(null);
                    isLoading = true;
                }
            }
        };
    }

    public void setLoading(boolean loading) {
        isLoading = loading;
    }

    public boolean isLoading() {
        return isLoading;
    }

    public void dispose() {
        recyclerView.removeOnScrollListener(scrollListener);
    }
}