I guess your app is a hybrid-mobile app, I mean cross platform not native app.
If so, I already did it with another app, I can send you a screenshot if you like.
I expect to add this feature in your app in just one day but I estimated 3 to let us test it well and also other integration circumstances.
A little brief about my self:
I'm a software developer and I have a quite good background about many technologies; Web Development as well as hybrid mobile development such As:
Ruby on rails, php, javascrip, angular 2, ionic, mysql and other stuff