SFRA / Server-side JS / Source: app_storefront_base/cartridge/scripts/hooks/taxes.js

'use strict';

var collections = require('*/cartridge/scripts/util/collections');
var ShippingLocation = require('dw/order/ShippingLocation');
var TaxMgr = require('dw/order/TaxMgr');
var Logger = require('dw/system/Logger');

/**
 * @typedef {Object} TaxField
 * @property {string} UUID - ID of the line item
 * @property {number|dw.value.Money} value - Either Tax Code or Tax Amount that should be applied to the line item.
 * @property {boolean} [amount=false] - Boolean indicating whether value field contains Tax Amount (true) or Tax Rate (false).
 */

/**
 * @typedef {Object} Response
 * @property {Array<TaxField>} taxes - List of taxes to line items UUIDs to be applied to the order
 * @property {Object} custom - List of custom properties to be attached to the basket
 */

/**
 * Calculate sales taxes
 * @param {dw.order.Basket} basket - current basket
 * @returns {Response} - An object that contains calculated taxes and custom properties
 */
function calculateTaxes(basket) {
    var taxes = [];

    var shipments = basket.getShipments();
    collections.forEach(shipments, function (shipment) {
        var taxJurisdictionId = null;

        if (shipment.shippingAddress) {
            var location = new ShippingLocation(shipment.shippingAddress);
            taxJurisdictionId = TaxMgr.getTaxJurisdictionID(location);
        }

        if (!taxJurisdictionId) {
            taxJurisdictionId = TaxMgr.defaultTaxJurisdictionID;
        }

        // if we have no tax jurisdiction, we cannot calculate tax
        if (!taxJurisdictionId) {
            return;
        }

        var lineItems = shipment.getAllLineItems();

        collections.forEach(lineItems, function (lineItem) {
            var taxClassId = lineItem.taxClassID;

            Logger.debug('1. Line Item {0} with Tax Class {1} and Tax Rate {2}', lineItem.lineItemText, lineItem.taxClassID, lineItem.taxRate);

            // do not touch line items with fix tax rate
            if (taxClassId === TaxMgr.customRateTaxClassID) {
                return;
            }

            // line item does not define a valid tax class; let's fall back to default tax class
            if (!taxClassId) {
                taxClassId = TaxMgr.defaultTaxClassID;
            }

            // if we have no tax class, we cannot calculate tax
            if (!taxClassId) {
                Logger.error('Line Item {0} has invalid Tax Class {1}', lineItem.lineItemText, lineItem.taxClassID);
                return;
            }

            // get the tax rate
            var taxRate = TaxMgr.getTaxRate(taxClassId, taxJurisdictionId);
            // w/o a valid tax rate, we cannot calculate tax for the line item
            if (!taxRate && taxRate !== 0) {
                return;
            }

            // calculate the tax of the line item
            taxes.push({ uuid: lineItem.UUID, value: taxRate, amount: false });
            Logger.debug('2. Line Item {0} with Tax Class {1} and Tax Rate {2}', lineItem.lineItemText, lineItem.taxClassID, lineItem.taxRate);
        });
    });

    return { taxes: taxes, custom: {} };
}

module.exports = {
    calculateTaxes: calculateTaxes
};