import getPath from './getPath'
import hasPath from './hasPath'

/**
 * 创建一个仅包含指定顶层属性的新对象。
 * @function pick
 * @memberof module:object
 * @param {Object} object 原对象
 * @param {string[]} keys 要保留的属性名
 * @returns {Object} 新对象，不修改原对象
 * @throws {TypeError} 参数类型不正确时抛出
 */
function pick(object, keys) {
  if (object === null || typeof object !== 'object') throw new TypeError('object must be an object')
  if (!Array.isArray(keys) || keys.some(key => typeof key !== 'string')) throw new TypeError('keys must be a string array')
  return keys.reduce((result, key) => {
    if (hasPath(object, key)) result[key] = getPath(object, key)
    return result
  }, {})
}

export default pick