Preorder Function on Woocommerce

We previously used the pre order plugin from Yith to control our website however since their new update it is not working as we needed it to and so we are looking for a custom solution.
Our stock is managed through third party software with an aPI Link

We need it so that when stock reaches zero, the add to cart function changes to say pre order, if the customer places the order it is marked that it was a pre order item on the back end but other than that it functions like a normal order, or possibly delays payment until its available but this part is not essential.

Once the api adds some stock back into the availability the product automatically goes back into add to cart not pre order.

Any solution should consider any speed impact on the website and should cause no disruption.

Yiths plugin is no longer putting things as add to cart ( in stock ) When stock becomes available again.