interface OrderItem {
  price: number;
  quantity: number;
}

function calculateTotalOrder(order: OrderItem[]) {
  return order.reduce((previous, current) => previous + current.price * current.quantity, 0)
}

function calculateDiscount(total: number, memberShip: string): number {
  const MIN_DISCOUNT_TOTAL = 100

  if (!["gold", "silver"].includes(memberShip)) return total;


  switch(memberShip) {
    case "gold": {
      const GOLD_MIN_DISCOUNT = 0.9, GOLD_MAX_DISCOUNT = 0.8
      return total * (total < MIN_DISCOUNT_TOTAL ? GOLD_MIN_DISCOUNT : GOLD_MAX_DISCOUNT);
    }
    case "silver": {
      const SILVER_MIN_DISCOUNT = 0.95, SILVER_MAX_DISCOUNT = 0.9
      return total * (total < MIN_DISCOUNT_TOTAL ? SILVER_MIN_DISCOUNT : SILVER_MAX_DISCOUNT);
    }
    default: return total;
  }
}

export function calculateOrderDiscount(order: OrderItem[], memberShip: string): number {
  const MIN_ORDER_TOTAL = 10, NO_RESULT = -1
  let total = calculateTotalOrder(order)
  if (total < MIN_ORDER_TOTAL) return NO_RESULT
  return calculateDiscount(total, memberShip);
}