UIKit/lib/utils/cart/cartDiscount.ts

import { CartData, Discount } from "../../model";
import { findDiscountFactor } from "./findDiscountFactor";


export function applyCartDiscount(
    cartData: CartData,
    discounts: Discount[],
) {
    const cartDiscount = findCartDiscount(cartData.priceAfterDiscounts, discounts);
    if (!cartDiscount) return;

    cartData.priceAfterDiscounts *= findDiscountFactor(cartDiscount);
    cartData.allAppliedDiscounts.push(cartDiscount);
    cartData.appliedCartPurchasesDiscount = cartDiscount;
}

export function findCartDiscount(
    cartPurchasesAmount: number,
    discounts: Discount[],
): Discount | null {
    const applicableDiscounts = discounts.filter(discount => {
        return (
            discount.Layer === 3 &&
            cartPurchasesAmount >= discount.Condition.CartPurchasesAmount
        );
    });

    if (!applicableDiscounts.length) return null;

    const maxValueDiscount = applicableDiscounts.reduce((prev, current) => {
        return current.Condition.CartPurchasesAmount > prev.Condition.CartPurchasesAmount ? current : prev;
    });

    return maxValueDiscount;
}