Best chatbot with prechat flow for Drupal

Hi,

We have been using Olark for a long time but it seems like the pre-chat function is pretty limited for Olark. We’d like to ask our customers a few questions before starting a live chat.

So I want a software that makes it possible to draw out a pre-chat flow. For example:

Are you an existing customer? Yes => Live-chat, No=> Please read our website. Do you still want personal support? => yes => Live chat

This is pretty basic but you get the idea.

Thanks