That'd be the hard way to do it and might not be possible.
I suggest you use an app like Localizer of Langify that can both help with setting up translations in a clean, SEO firendly way and also do automatic location based redirection.
I haven't used any of those apps yet mainly because multi-language isn't our priority, but I'm planning to.
Thanks your prompt reply. Yes. It turned out that create dual theme to realize dual-language are both time-comsuming and costing. The best way we found is, like you mentioned, use localizer. I think the DIY translate service is great as you can control the accuracy of language.
Hope you create your dual business soon.:)