# Service class emulates Rails ActiveRecord
class ActiveRecord
  def initialize(params={}); end
end

# Order model
class Order < ActiveRecord
  attr_accessor :country_code, 
                :first_name, 
                :last_name, 
                :gross_price, 
                :website
    
  def valid?
    !gross_price.nil?
  end
  
  def errors
    [].tap{|e| e << {some_attr: 'Error message'}}
  end
  
  def self.last
    all.last
  end
  
  def self.all
    [
      Order.new(country_code: 'RU', 
          first_name: 'Petr', 
          last_name: 'Sergeev', 
          gross_price: 10)
    ]
  end
end

# Service class emulates Rails ApplicationController
class ApplicationController
  def render(params)
    puts params[:json].inspect
  end
end

# Orders Controller
class OrdersController < ApplicationController
  def create(params)
    @gross_price = params[:gross_price]
    @website = params[:website]
    @country_code = params[:country_code] || previous_order.country_code
    @first_name = params[:first_name] || previous_order.first_name
    @last_name = params[:last_name] || previous_order.last_name
  

    order = Order.new(checkout_params.merge(price_params))
    order.website = @website
    order.gross_price = price_params[:gross_price]

    if order.valid?
      render json: {order: order}
    else
      render json: {errors: order.errors}
    end
  end
  
  def previous_order
    Order.last
  end

  def checkout_params
    return @checkout_params if @checkout_params
    
    @checkout_params = {
      first_name: @first_name,
      last_name: @last_name,
      country_code: @country_code,
    }
  end

  def price_params
    @price_params = @price_params || {
      gross_price: @gross_price
    }
  end
end

# Samples
OrdersController.new.create(country_code: 'DE', first_name: 'Alex', gross_price: 10 )
OrdersController.new.create(country_code: 'DE', first_name: 'Alex' )