/* 基础小工具，可通用于服务端和用户端
 */

module.exports = {
  sleep: (ms) => new Promise((resolve, reject) => setTimeout(resolve, ms)),

  parseJsonPossible(value) {
    try {
      return JSON.parse(value)
    } catch (e) {
      return value
    }
  },

  sortAndFilterJson({ fields, entity, exclude = [] } = {}) {
    const newEntity = {}
    for (let key of Object.keys(fields).sort()) {
      if (typeof (entity[key] !== 'undefined') && !Number.isNaN(entity[key]) && entity[key] !== Infinity) {
        newEntity[key] = entity[key]
      }
    }
    for (let exkey of exclude) {
      delete newEntity[exkey]
    }
    return JSON.stringify(newEntity)
  },

  name2port(name='') {
    let port = name.toLowerCase()
      .replace(/[abc]/g, 2)
      .replace(/[def]/g, 3)
      .replace(/[ghi]/g, 4)
      .replace(/[jkl]/g, 5)
      .replace(/[mno]/g, 6)
      .replace(/[pqrs]/g, 7)
      .replace(/[tuv]/g, 8)
      .replace(/[wxyz]/g, 9)
    return parseInt(port)
  },

  /**
   * 用户编号转邀请码
   *
   * @static
   * @param {*} aiid
   * @return {*}
   * @memberof TICrypto
   */
  aiid2regcode(aiid) {
    const alphabet = 'e5fcdg3hqa4b1n0pij2rstuv67mwx89klyz'
    const base = 16367
    let num = (aiid + base) * (base - alphabet.length)
    let code = ''
    let mod
    while (num > 0) {
      mod = num % alphabet.length
      num = (num - mod) / alphabet.length
      code = code + alphabet[mod] // 倒序存放
    }
    return code
  },

  /**
   * 邀请码转用户编号
   *
   * @static
   * @param {*} code
   * @return {*}
   * @memberof TICrypto
   */
  regcode2aiid(code) {
    if (typeof code === 'string' && /^[a-zA-Z0-9]+$/.test(code)) {
      const alphabet = 'e5fcdg3hqa4b1n0pij2rstuv67mwx89klyz'
      const base = 16367
      code = code.toLowerCase()
      let len = code.length
      let num = 0
      for (let i = 0; i < len; i++) {
        num += alphabet.indexOf(code[i]) * Math.pow(alphabet.length, i)
      }
      let aiid = num / (base - alphabet.length) - base
      if (aiid >= 0 && Number.isInteger(aiid)) {
        // 允许 aiid===0：当第一个用户（aiid==1）登录时，需要一个系统默认的邀请码。
        return aiid
      }
    }
    return null // null 代表一切非法的regcode
  },

}