Switching the enviroment

[eluser]Unknown[/eluser]
Hello,
I am trying to make an application that will sometimes need to run offline using a local database.
The way I'm envisioning this is if the users click a button that says "switch to offline mode" then the application will change things, Certain features will be disabled, the database will change from the webserver to localhost. I can already do the changes within the application by switching the enviroment manually from production to offline in the index.php file. is there a way to change this from within the app?
Thanks!