Adds support for confirming SetupIntent on backend (#61)

* Adds conditional SetupIntent confirmation on create and new confirm_setup_intent endpoint

* Remove authenticate.

* Fix typo

* Don't need separate confirm.

Author: csabol-stripe

web.rb

@@ -129,9 +129,17 @@ def authenticate!
 # Just like the `/capture_payment` endpoint, a real implementation would include controls
 # to prevent misuse
 post '/create_setup_intent' do
+  payload = params
+  if request.content_type.include? 'application/json' and params.empty?
+      payload = Sinatra::IndifferentHash[JSON.parse(request.body.read)]
+  end
   begin
     setup_intent = Stripe::SetupIntent.create({
       payment_method_types: ['card'],
+      payment_method: payload[:payment_method],
+      return_url: payload[:return_url],
+      confirm: payload[:payment_method] != nil,
+      use_stripe_sdk: payload[:payment_method] != nil ? true : nil,
     })
   rescue Stripe::StripeError => e
     status 402