How to limit quantity for variant products in a dropdown menu?

[shadowdk]

i have variant product listed in drop down menu. i want to set limit for this options. Example if user select first option then  user can add only product and for other option he/she can buy same product as many as quantity.

In product page, i want to show warning message if already product is in cart and it have limit to 1 quantity and in cart page there should be no quantity field for that variant product or can't editable quantity field
so please help me out i can do it.
thanks