How to handle case of not-empty queue?

[fringe patio]

I have following code for cyclic queue:

and it doesn't treat case of only "enqueue" operation, so after these operations i get smth for example [1,2,3,4] where head=tail=0 after, but queue isn't empty 😦 How can I fix that?

[chilly bay]

<@&987246399047479336> please have a look, thanks.