import uuid from './uuid'
/* eslint no-useless-escape: "off" */
const SPECIAL_CHARS_REGEXP = /([\:\-\_]+(.))/g
const MOZ_HACK_REGEXP = /^moz([A-Z])/

const trim = function (string) {
  return (string || '').replace(/^[\s\uFEFF]+|[\s\uFEFF]+$/g, '')
}

/**
 * stamp string
 * @param obj
 * @returns {*}
 */
const stamp = function (obj) {
  let key = '_event_id_'
  obj[key] = obj[key] || (uuid())
  return obj[key]
}

/**
 * check case
 * @param name
 * @returns {string}
 */
const camelCase = function (name) {
  return name.replace(SPECIAL_CHARS_REGEXP, function (_, separator, letter, offset) {
    return offset ? letter.toUpperCase() : letter
  }).replace(MOZ_HACK_REGEXP, 'Moz$1')
}

/**
 * 判断是否为对象
 * @param value
 * @returns {boolean}
 */
const isObject = value => {
  const type = typeof value
  return value !== null && (type === 'object' || type === 'function')
}

/**
 * 判断是否为合法字符串
 * @param value
 * @returns {boolean}
 */
const isString = (value) => {
  if (value == null) {
    return false
  }
  return typeof value === 'string' || (value.constructor !== null && value.constructor === String)
}

/**
 * check is number
 * @param val
 * @returns {boolean}
 */
const isNumber = (val) => {
  return typeof val === 'number' && !isNaN(val);
}

/**
 * merge
 * @param a
 * @param b
 * @returns {*}
 */
const merge = (a, b) => {
  for (const key in b) {
    if (isObject(b[key]) && isObject(a[key])) {
      merge(a[key], b[key])
    } else {
      a[key] = b[key]
    }
  }
  return a
}

export {
  merge,
  trim,
  stamp,
  isString,
  isObject,
  camelCase,
  isNumber
}