Shopify GEOlocation dev

Hi there,

We are looking a way on how to redirect customers by their IP address on our Shopify website. All markets are done, subdomains are connected to each language. 

For an example: We have primary website www.myshopify.com but if you are from Croatia we have subdomain www.hr.myshopify.com and we want it to be automatically redirected to it. All subdomains are localized.

We are interested in code and not in apps. Searching Google did not help much:)

Thanks