/*
  开发环境不开启定时器
 */
const isStartTimer = process.env.NODE_ENV !== 'development'

/**
 * @function 定时器
 * @param fn { function } 执行过程
 * @param duration { timestamp } 间隔时间
 * @param immediate { boolean } 是否立即执行
 * @returns {{stop(): void, restart: restart}}
 */
export default function timer(fn, duration = 5 * 1000, immediate = true) {
  // 执行队列
  let processes = []
  let _args = []
  // 定义定时器
  let timer = null
  let _duration = duration
  // 过程支持list和单一函数
  if (Array.isArray(fn)) {
    processes.push.apply(processes, fn)
  } else {
    processes.push(fn)
  }
  /**
   * @function 过程执行器
   * @param processes { Array<function> | function }
   * @param args { any }
   * @returns {Promise<void>}
   */
  const exec = async (processes, ...args) => {
    _args = args
    try {
      if (timer) {
        clearTimeout(timer)
        timer = null
      }
      for (let process of processes) {
        if (typeof process === 'function') {
          await process(..._args)
        }
      }
    } catch (e) {
      console.error('TimerError:', e)
    } finally {
      if (!isStartTimer) return false
      timer = setTimeout(() => {
        exec(processes, ..._args)
      }, _duration)
    }
  }
  if (immediate) {
    exec(processes)
  }
  return {
    stop () {
      if (timer) {
        clearTimeout(timer)
        timer = null
        processes = null
        _args = null
      }
    },
    clearParams () {
      _args = []
    },
    /**
     * 定时器重启
     * @param args { { params: Array<any>, duration: number } } 回调的参数
     */
    restart: function (options = {}) {
      const { params = [], duration } = options
      // 不能用全等，对象中的undefined 与 undefined 不是全等
      if (duration != undefined || duration != null) {
        _duration = duration
      }
      exec(processes, ...(params || []))
    }
  }
}