module.exports = clone;

/*
  Deep clones all properties except functions

  var arr = [1, 2, 3];
  var subObj = {aa: 1};
  var obj = {a: 3, b: 5, c: arr, d: subObj};
  var objClone = clone(obj);
  arr.push(4);
  subObj.bb = 2;
  obj; // {a: 3, b: 5, c: [1, 2, 3, 4], d: {aa: 1}}
  objClone; // {a: 3, b: 5, c: [1, 2, 3], d: {aa: 1, bb: 2}}
*/

function clone(obj) {
  let result = obj;
  var type = {}.toString.call(obj).slice(8, -1);
  if (type == 'Set') {
    return new Set([...obj].map(value => clone(value)));
  }
  if (type == 'Map') {
    return new Map([...obj].map(kv => [clone(kv[0]), clone(kv[1])]));
  }
  if (type == 'Date') {
    return new Date(obj.getTime());
  }
  if (type == 'RegExp') {
    return RegExp(obj.source, getRegExpFlags(obj));
  }
  if (type == 'Array' || type == 'Object') {
    result = Array.isArray(obj) ? [] : {};
    for (var key in obj) {
      // include prototype properties
      result[key] = clone(obj[key]);
    }
  }
  // primitives and non-supported objects (e.g. functions) land here
  return result;
}

function getRegExpFlags(regExp) {
  if (typeof regExp.source.flags == 'string') {
    return regExp.source.flags;
  } else {
    var flags = [];
    regExp.global && flags.push('g');
    regExp.ignoreCase && flags.push('i');
    regExp.multiline && flags.push('m');
    regExp.sticky && flags.push('y');
    regExp.unicode && flags.push('u');
    return flags.join('');
  }
}