Get highest profit

highest_profit.rb

def highest_profit(stock_prices)
  lowest = buy = sell = stock_prices.shift
  stock_prices.each do |price|
    current_profit = sell - buy
    if (price - lowest) > current_profit
      buy = lowest
      sell = price
    end
    if price < lowest
      lowest = price
    end
  end
  {buy: buy, sell: sell, profit: (sell - buy)}
end

puts highest_profit([5, 6, 4, 7, 9, 8, 8]) # {:buy=>4, :sell=>9, :profit=>5}

puts highest_profit([10, 12, 11, 20, 4, 9, 8, 8]) # {:buy=>10, :sell=>20, :profit=>10}