Add exchange rates endpoint

app/controllers/application_controller.rb

@@ -5,7 +5,7 @@ class ApplicationController < ActionController::Base
     request.format = :csv
   end
 
-  def index
+  def prices
     games     = Game.all.includes(:prices).sort_by(&:title).group_by(&:parsed_game_code)
     countries = Price.pluck(:country).uniq.sort
     currency  = Price.pluck(:currency).include?(params[:currency]) ? params[:currency] : nil
@@ -30,4 +30,26 @@ def index
       format.csv { send_data csv }
     end
   end
+
+  def rates
+    exchange_rates  = ExchangeRate.all
+    currencies      = exchange_rates.pluck(:from).uniq.sort
+
+    csv = CSV.generate(headers: true) do |rows|
+      rows << [''].concat(currencies)
+
+      currencies.each do |from|
+        row = [from]
+        currencies.each do |to|
+          exchange_rate = exchange_rates.find_by(from: from, to: to)
+          row << (exchange_rate.present? ? exchange_rate.rate : 1)
+        end
+        rows << row
+      end
+    end
+
+    respond_to do |format|
+      format.csv { send_data csv }
+    end
+  end
 end

config/routes.rb

@@ -1,5 +1,6 @@
 Rails.application.routes.draw do
   # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
 
-  get :prices, to: 'application#index'
+  get :prices, to: 'application#prices'
+  get :rates, to: 'application#rates'
 end