type ExecutePromotionItemActionFn<T extends PromotionActionArgs> = (
    orderItem: OrderItem,
    orderLine: OrderLine,
    args: ConfigArgValues<T>,
    utils: PromotionUtils,
) => number | Promise<number>

type ExecutePromotionOrderActionFn<T extends PromotionActionArgs> = (
    order: Order,
    args: ConfigArgValues<T>,
    utils: PromotionUtils,
) => number | Promise<number>

interface PromotionItemActionConfig<T extends PromotionActionArgs> extends PromotionActionConfig<T> {
  execute: ExecutePromotionItemActionFn<T>;
}

interface PromotionOrderActionConfig<T extends PromotionActionArgs> extends PromotionActionConfig<T> {
  execute: ExecutePromotionOrderActionFn<T>;
}

class PromotionAction<T extends PromotionActionArgs = {}> extends ConfigurableOperationDef<
    T
> {
  readonly readonly priorityValue: number;
  constructor(config: PromotionActionConfig<T>)
}

// Applies a percentage discount to each OrderItem
const itemPercentageDiscount = new PromotionItemAction({
    code: 'item_percentage_discount',
    args: { discount: 'percentage' },
    execute(orderItem, orderLine, args) {
        return -orderLine.unitPrice * (args.discount / 100);
    },
    description: 'Discount every item by { discount }%',
});

class PromotionItemAction<T extends PromotionActionArgs = {}> extends PromotionAction<T> {
  constructor(config: PromotionItemActionConfig<T>)
}

// Applies a percentage discount to the entire Order
const orderPercentageDiscount = new PromotionOrderAction({
    code: 'order_percentage_discount',
    args: { discount: 'percentage' },
    execute(order, args) {
        return -order.subTotal * (args.discount / 100);
    },
    description: 'Discount order by { discount }%',
});

class PromotionOrderAction<T extends PromotionActionArgs = {}> extends PromotionAction<T> {
  constructor(config: PromotionOrderActionConfig<T>)
}