Shopify website (ruby on rails) Country selector and redirect

We have 3 stores based on the Shopify eCommerce platform, the store is split into 3 sub-domain, UK, USA and Europe. We want to have a county selector pop out for all new customers landing on the site similar to [login to view URL] once a customer has selected a country they will be redirected to the correct sub-domain so that all the prices and delivery options are correct for them. A cookie should save the option they click so that when the revisit the site they don't have to select a country again. Only bid if you are able to work on shopify projects and ruby on rails. We will need to see your previous shopify work before we can select you.