Change language runtime

Hi
On my shop website, I need to change shop language auto with user IP
For example, if a user is from Turkey, so load Turkey language or English language for America
I load English language default
I try to change the language in the config file but I cannot use the $this->db command and got error
I have country IPs in database and use query for detect user country with ip
And that is important check IP before set $config['language'] parameter
Thanks