/**
* Clone object and all it's properties.
* Works recursively.
*
* @param  {Object} obj  Object to clone.
* @param  {Mixed}  seen For internal use only. Don't set.
* @return {Object}      The clone.
*/
export const clone = (obj, seen) => {
  if (typeof obj !== 'object' || obj === null) {
    return obj;
  }
  seen = seen || new Map();
  const lookup = seen.get(obj);
  if (lookup) {
    return lookup;
  }
  let newObj;
  let cloneDeep = false;
  if (!Array.isArray(obj)) {
    if (obj instanceof Date) {
      newObj = new Date(obj.getTime());
    } else if (obj instanceof RegExp) {
      newObj = new RegExp(obj);
    } else {
      const proto = Object.getPrototypeOf(obj);
      if (proto && Object.isFrozen(obj)) {
        newObj = obj;
      } else {
        newObj = Object.create(proto);
        cloneDeep = true;
      }
    }
  } else {
    newObj = [];
    cloneDeep = true;
  }
  seen.set(obj, newObj);
  if (cloneDeep) {
    const keys = Object.getOwnPropertyNames(obj);
    for (let i = 0; i < keys.length; ++i) {
      const key = keys[i];
      const descriptor = Object.getOwnPropertyDescriptor(obj, key);
      if (descriptor && (descriptor.get || descriptor.set)) {
        Object.defineProperty(newObj, key, descriptor);
      } else {
        newObj[key] = this._clone(obj[key], seen);
      }
    }
  }
  return newObj;
};