vending_machine.rb

require "pry"

class VendingMachine
  ACCEPTABLE_MONEY = [10, 50, 100, 500, 1_000].freeze

  # stocks: 現在の在庫
  # total_money_amount: 現在の投入金額合計
  # sales_amount: 売上金額合計
  attr_reader :total_money_amount, :sales_amount
  attr_writer :stocks

  def initialize(stocks: {})
    @total_money_amount = 0
    # stocsk は
    # {
    #   {'コーラ' => {price: 120, count: 5}},
    #   {'オレンジジュース' => {price: 100, count: 2}},
    #   {'エナジードリンク' => {price: 200, count: 4}}
    # }
    # のようなハッシュでもってみる
    @stocks = stocks.dup
    @sales_amount = 0
  end

  def stocks
    @stocks.dup
  end

  def insert_money(money)
    return money unless ACCEPTABLE_MONEY.include?(money)

    @total_money_amount += money
  end

  def refund
    change = @total_money_amount
    @total_money_amount = 0

    change
  end

  def sell(drink_name)
    if can_buy?(drink_name)
      @stocks[drink_name][:count] -= 1
      @sales_amount += @stocks[drink_name][:price]
      @total_money_amount -= @stocks[drink_name][:price]

      @total_money_amount
    end
  end

  def add_stock(drink)
    @stocks = @stocks.merge(drink)
  end

  def buyable_drinks
    # XXX インデックスでアクセスするのがダサいしわかりづらく感じる
    @stocks.each_with_object([]) do |drink, memo|
      memo << drink[0] if drink[1][:price] <= @total_money_amount
    end
  end

  private

  def can_buy?(drink_name)
    return false unless @stocks

    price = @stocks[drink_name][:price]
    count = @stocks[drink_name][:count]

    (total_money_amount >= price) && (count >= 1)
  end
end