重构此函数以将其认知复杂度从 19 降低到允许的 14

Question

我正在使用 angular 和节点创建一个项目，在我的项目中，我编写了一个函数，其中有很多具有多个条件的 if 和 else if 语句。我遇到了认知复杂性问题。我浏览了一些链接，但我无法理解如何在不影响此方法用户的情况下更改我的代码。

const isAdyenProvider = orderRequest.paymentProvider === OrderRequestV2.PaymentProviderEnum.ADYEN;
    if (
      (
        !orderRequest.paymentProvider
        || isAdyenProvider
      )
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.CREDITCARD
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.CREDIT_CARD, true);
      const giftCardPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.GIFT_CERTIFICATE);

      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.AdyenCreditCardPaymentMethodService
      };

      const giftCardsPayments = this.getGiftCardsPayments(giftCardPaymentInstruments);

      return [
        mainPayment,
        ...giftCardsPayments
      ];
    } else if (
      isAdyenProvider
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.PAYPAL
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.ADYEN_PAYPAL, true);
      const giftCardPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.GIFT_CERTIFICATE);

      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.adyenPayPalPaymentMethodService
      };

      const giftCardsPayments = this.getGiftCardsPayments(giftCardPaymentInstruments);

      return [
        mainPayment,
        ...giftCardsPayments
      ];
    } else if (
      (
        !orderRequest.paymentProvider
        || isAdyenProvider
      )
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.INVOICE
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.INVOICE, true);
      const giftCardPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.GIFT_CERTIFICATE);

      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.AdyenInvoicePaymentMethodService
      };

      const giftCardsPayments = this.getGiftCardsPayments(giftCardPaymentInstruments);

      return [
        mainPayment,
        ...giftCardsPayments
      ];
    }  else if (
      orderRequest.paymentProvider === OrderRequestV2.PaymentProviderEnum.COD
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.COD
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.CASH_ON_DELIVERY, true);
      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.CashOnDeliveryPaymentService
      };
      return [mainPayment];
    } else if (
      (
        !orderRequest.paymentProvider
        || isAdyenProvider
      )
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.GIFTCERTIFICATE
    ) {
      const giftCardPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.GIFT_CERTIFICATE, true);
      return this.getGiftCardsPayments(giftCardPaymentInstruments);
    } else if (
      (
        !orderRequest.paymentProvider
        || isAdyenProvider
      )
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.APPLEPAY
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.APPLE_PAY, true);
      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.AdyenApplePayPaymentService
      };
      return [mainPayment];
    } else if (
      (
        !orderRequest.paymentProvider
        || isAdyenProvider
      )
      && orderRequest.paymentMethod === OrderRequestV2.PaymentMethodEnum.SHOPRUNNER
    ) {
      const mainPaymentInstruments = await this.pickPaymentInstruments(basket, constants.PAYMENT_METHODS.CREDIT_CARD, true);
      const mainPayment = {
        paymentInstrument: mainPaymentInstruments[0],
        paymentMethod: this.AdyenShoprunnerPaymentService
      };
      return [mainPayment];
    }
    throw new BadRequestError(`${ERRORS.PLACE_ORDER_V2_PREFIX} Please verify your request`);