'use strict';
// 19.1.2.1 Object.assign(target, source, ...)
var DESCRIPTORS = require('./_descriptors');
var getKeys = require('./_object-keys');
var gOPS = require('./_object-gops');
var pIE = require('./_object-pie');
var toObject = require('./_to-object');
var IObject = require('./_iobject');
var $assign = Object.assign;

// should work with symbols and should have deterministic property order (V8 bug)
module.exports = !$assign || require('./_fails')(function () {
  var A = {};
  var B = {};
  // eslint-disable-next-line no-undef
  var S = Symbol();
  var K = 'abcdefghijklmnopqrst';
  A[S] = 7;
  K.split('').forEach(function (k) { B[k] = k; });
  return $assign({}, A)[S] != 7 || Object.keys($assign({}, B)).join('') != K;
}) ? function assign(target, source) { // eslint-disable-line no-unused-vars
  var T = toObject(target);
  var aLen = arguments.length;
  var index = 1;
  var getSymbols = gOPS.f;
  var isEnum = pIE.f;
  while (aLen > index) {
    var S = IObject(arguments[index++]);
    var keys = getSymbols ? getKeys(S).concat(getSymbols(S)) : getKeys(S);
    var length = keys.length;
    var j = 0;
    var key;
    while (length > j) {
      key = keys[j++];
      if (!DESCRIPTORS || isEnum.call(S, key)) T[key] = S[key];
    }
  } return T;
} : $assign;