kibana/examples/embeddable_examples/server/merge_migration_function_maps.ts

/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

import { mergeWith } from 'lodash';
import type { SerializableRecord } from '@kbn/utility-types';
import { MigrateFunctionsObject, MigrateFunction } from '@kbn/kibana-utils-plugin/common';

export const mergeMigrationFunctionMaps = (
  obj1: MigrateFunctionsObject,
  obj2: MigrateFunctionsObject
) => {
  const customizer = (objValue: MigrateFunction, srcValue: MigrateFunction) => {
    if (!srcValue || !objValue) {
      return srcValue || objValue;
    }
    return (state: SerializableRecord) => objValue(srcValue(state));
  };

  return mergeWith({ ...obj1 }, obj2, customizer);
};