iopa/src/util/prototype.ts

API-first, Internet of Things (IoT) stack for Typescript, official implementation of the Internet Open Protocols Alliance (IOPA) reference pattern

/*
 * Internet Open Protocol Abstraction (IOPA)
 * Copyright (c) 2016-2022 Internet Open Protocols Alliance
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/**
 * Create alias access methods on context.response for context body elemeent for given stream/readable/writable prototype
 *
 * Note: the alias will be a collection of both functions (which simply shell out to target function) and valuetypes (which
 * have a getter and setter defined which each shell out to the target property)
 *
 * @method cloneKeyBehaviors
 *
 * @param targetObjectPrototype (__proto__)  the prototype object for the context.response object on which the alias properties are set
 * @param sourceObjectprototype (__proto__)  the prototpye object for the generic stream/writable on which to enumerate all properties
 * @param iopaContextKey (string) e.g., "iopa.Body"
 * @returns (void)
 * @private
 */
export default function cloneKeyBehaviors(
  targetObjectPrototype: any,
  sourceObjectprototype: any,
  iopaContextKey: string,
  response: any
): void {
  Object.getOwnPropertyNames(sourceObjectprototype).forEach((srcProp) => {
    if (typeof sourceObjectprototype[srcProp] === 'function') {
      targetObjectPrototype[srcProp] = (...rest: any[]) => {
        let item
        if (response) {
          item = targetObjectPrototype[iopaContextKey]
        } else {
          item = targetObjectPrototype.response[iopaContextKey]
        }

        return item[srcProp](...rest)
      }
    } else {
      Object.defineProperty(targetObjectPrototype, srcProp, {
        get() {
          let item
          if (response) {
            item = this[iopaContextKey]
          } else {
            item = this.response[iopaContextKey]
          }

          return item[srcProp]
        },

        set(val: any) {
          let item
          if (response) {
            item = this[iopaContextKey]
          } else {
            item = this.response[iopaContextKey]
          }

          item[srcProp] = val
        }
      })
    }
  })
}