/*!
 * merge-descriptors
 * Copyright(c) 2014 Jonathan Ong
 * Copyright(c) 2015 Douglas Christopher Wilson
 * MIT Licensed
 */

'use strict';

/**
 * Module exports.
 * @public
 */

module.exports = merge;

/**
 * Module variables.
 * @private
 */

var hasOwnProperty = Object.prototype.hasOwnProperty;

/**
 * Merge the property descriptors of `src` into `dest`
 *
 * @param {object} dest Object to add descriptors to
 * @param {object} src Object to clone descriptors from
 * @param {boolean} [redefine=true] Redefine `dest` properties with `src` properties
 * @returns {object} Reference to dest
 * @public
 */

function merge(dest, src, redefine) {
  if (!dest) {
    throw new TypeError('argument dest is required');
  }

  if (!src) {
    throw new TypeError('argument src is required');
  }

  if (redefine === undefined) {
    // Default to true
    redefine = true;
  }

  Object.getOwnPropertyNames(src).forEach(
    function forEachOwnPropertyName(name) {
      if (!redefine && hasOwnProperty.call(dest, name)) {
        // Skip descriptor
        return;
      }

      // Copy descriptor
      var descriptor = Object.getOwnPropertyDescriptor(src, name);
      Object.defineProperty(dest, name, descriptor);
    }
  );

  return dest;
}