woocommerce/plugins/woocommerce-blocks/packages/checkout/registry/index.js

/**
 * External dependencies
 */
import { useMemo } from '@wordpress/element';
import { CURRENT_USER_IS_ADMIN } from '@woocommerce/block-settings';

/**
 * Internal dependencies
 */
import { returnTrue } from '../';

let checkoutFilters = {};

/**
 * Register filters for a specific extension.
 *
 * @param {string} namespace Name of the extension namespace.
 * @param {Object} filters   Object of filters for that namespace. Each key of
 *                           the object is the name of a filter.
 */
export const __experimentalRegisterCheckoutFilters = ( namespace, filters ) => {
	checkoutFilters = {
		...checkoutFilters,
		[ namespace ]: filters,
	};
};

/**
 * Get all filters with a specific name.
 *
 * @param {string} filterName   Name of the filter to search for.
 * @return {Function[]} Array of functions that are registered for that filter
 *                      name.
 */
const getCheckoutFilters = ( filterName ) => {
	const namespaces = Object.keys( checkoutFilters );
	const filters = namespaces
		.map( ( namespace ) => checkoutFilters[ namespace ][ filterName ] )
		.filter( Boolean );
	return filters;
};

/**
 * Apply a filter.
 *
 * @param {Object} o                Object of arguments.
 * @param {string} o.filterName     Name of the filter to apply.
 * @param {any}    o.defaultValue   Default value to filter.
 * @param {Object} [o.extensions]   Values extend to REST API response.
 * @param {any}    [o.arg]          Argument to pass to registered functions.
 *                                  If several arguments need to be passed, use
 *                                  an object.
 * @param {Function} [o.validation] Function that needs to return true when
 *                                  the filtered value is passed in order for
 *                                  the filter to be applied.
 * @return {any} Filtered value.
 */
export const __experimentalApplyCheckoutFilter = ( {
	filterName,
	defaultValue,
	extensions,
	arg = null,
	validation = returnTrue,
} ) => {
	return useMemo( () => {
		const filters = getCheckoutFilters( filterName );

		let value = defaultValue;
		filters.forEach( ( filter ) => {
			try {
				const newValue = filter( value, extensions, arg );
				value = validation( newValue ) ? newValue : value;
			} catch ( e ) {
				if ( CURRENT_USER_IS_ADMIN ) {
					throw e;
				} else {
					// eslint-disable-next-line no-console
					console.error( e );
				}
			}
		} );
		return value;
	}, [ filterName, defaultValue, extensions, arg, validation ] );
};