import { ref, Ref } from 'vue'

interface CountdownTimerOptions {
  delay?: number
  cacheKey?: string
}

/**
 * 倒计时
 * - Ref countdown、isCounting
 * - Fn start、stop
 */
class CountdownTimer {
  delay: number
  cacheKey: string
  isCounting: Ref<boolean>
  countdown: Ref<number>
  countdownTimer: any

  constructor({ delay, cacheKey }: CountdownTimerOptions = {}) {
    this.delay = delay || 59
    this.cacheKey = cacheKey || 'sms-count-timer'
    this.isCounting = ref(false)
    this.countdown = ref(0)
    this.countdownTimer = null

    this.recoverCacheCountdown()
  }

  /**
   * 对外提供调用
   */
  getInstance() {
    return {
      countdown: this.countdown,
      isCounting: this.isCounting,
      start: this.startCountdown.bind(this),
      stop: this.stopTimer.bind(this)
    }
  }

  /**
   * 开始倒计时
   */
  startCountdown() {
    if (!this.isCounting.value) {
      if (this.cacheKey) {
        localStorage.setItem(this.cacheKey, Date.now().toString())
      }
      this.countdown.value = this.delay
      this.startTimer()
    }
  }

  /**
   * 恢复缓存倒计时
   */
  recoverCacheCountdown() {
    if (this.cacheKey && localStorage.getItem(this.cacheKey)) {
      const cacheDelay = this.calcCountdown(
        parseInt(localStorage.getItem(this.cacheKey))
      )
      if (cacheDelay) {
        this.countdown.value = cacheDelay
        this.startTimer()
      }
    }
  }

  /**
   * 计算倒计时，如果超过60秒则不再计算
   * @param start - 需要与当前时间对比的开始时间，ms
   */
  calcCountdown(start) {
    const startTime = parseInt(start) || Date.now()
    const diffTime = Math.ceil((Date.now() - startTime) / 1000)

    if (diffTime > 0 && diffTime <= this.delay) {
      return this.delay - diffTime
    }
    return 0
  }

  /**
   * 开始倒计时
   */

  startTimer() {
    this.isCounting.value = true
    this.countdownTimer = setInterval(() => {
      this.countdown.value--
      if (this.countdown.value <= 0) {
        this.isCounting.value = false
        clearInterval(this.countdownTimer)
        if (this.cacheKey) {
          localStorage.removeItem(this.cacheKey)
        }
      }
    }, 1000)
  }

  /**
   * 停止倒计时
   */
  stopTimer() {
    clearInterval(this.countdownTimer)
  }
}

export default CountdownTimer