company_market_updates_service.rb

class CompanyMarketUpdatesService
  def initialize(notification_job: NotificationJob.new)
    @notification_job = notification_job
  end

  def update(params)
    Company.find_by_stock_symbol(params[:stock_symbol])&.tap do |company|
      should_notify = should_notify_stock_price_reduction?(company.stock_price, params[:stock_price])
      company.update(params)
      notify_stock_price_reduction(company) if should_notify
    end
  end

  private

  def should_notify_stock_price_reduction?(previous_stock_price, current_stock_price)
    previous_stock_price > current_stock_price
  end

  def notify_stock_price_reduction(company)
    @notification_job.perform(message: "Stock price for #{company.stock_symbol} down to #{company.stock_price}")
  end
end