refactor payment#purchase method, improve environment variable names

app/controllers/payments_controller.rb

@@ -16,7 +16,7 @@ class PaymentsController < ApplicationController
     @payment = Payment.new(payment_params)
     @total_amount_to_pay = Ticket.total_price(@conference, current_user, paid: false)
 
-    if @payment.purchase(current_user, @conference, price_in_cents) && @payment.save
+    if @payment.purchase && @payment.save
       update_purchased_ticket_purchases
       redirect_to conference_conference_registration_path(@conference.short_title), flash: { success: 'Thanks! You have purchased your tickets successfully.' }
     else
@@ -26,10 +26,6 @@ class PaymentsController < ApplicationController
 
   private
 
-  def price_in_cents
-    (@payment.amount * 100).round
-  end
-
   def update_purchased_ticket_purchases
     paid_ticket_purchases = current_user.ticket_purchases.by_conference(@conference).unpaid
     paid_ticket_purchases.each do |ticket|
@@ -40,6 +36,8 @@ class PaymentsController < ApplicationController
   end
 
   def payment_params
-    params.require(:payment).permit(:first_name, :last_name, :credit_card_number, :expiration_month, :expiration_year, :card_verification_value, :amount)
+    params.require(:payment)
+      .permit(:first_name, :last_name, :credit_card_number, :expiration_month, :expiration_year, :card_verification_value, :amount)
+      .merge(user: current_user, conference: @conference)
   end
 end

app/controllers/ticket_purchases_controller.rb

@@ -4,7 +4,7 @@ class TicketPurchasesController < ApplicationController
   authorize_resource :conference_registrations, class: Registration
 
   def create
-    TicketPurchase.destroy_all(user_id: current_user.id, conference_id: @conference.id, paid: false)
+    TicketPurchase.by_conference(@conference).unpaid.by_user(current_user).destroy_all
     message = TicketPurchase.purchase(@conference, current_user, params[:tickets][0])
     if message.blank?
       if current_user.ticket_purchases.by_conference(@conference).unpaid.any?