import { computed, onBeforeUnmount, ref } from 'vue'
import { useRoute } from 'vue-router'

import {
  cancelFaultRecordOperation,
  createFaultRecordOperation,
  getFaultRecordOperation,
} from '@/service/faultRecord'
import type {
  FaultRecordCreateReq,
  FaultRecordEnv,
  FaultRecordOpDetail,
} from '@/service/faultRecord/interface'

import { ENV_LABEL, errText, isTerminal } from './constants'

/** 当前页面所属环境（来自路由 meta.env） */
export function useFaultRecordEnv() {
  const route = useRoute()
  const env = computed<FaultRecordEnv>(() => (route.meta.env === 'test' ? 'test' : 'prod'))
  const envLabel = computed(() => ENV_LABEL[env.value])
  return { env, envLabel }
}

// 轮询间隔：开始后 10 秒内每 2 秒（及时看到设备应答），之后每 5 秒（等待 379／上传／下载，状态变化慢）
const POLL_FAST_INTERVAL = 2000
const POLL_FAST_PERIOD = 10_000
const POLL_SLOW_INTERVAL = 5000

/** 创建操作并轮询状态，直到结束 */
export function useOperation(onFinished?: (d: FaultRecordOpDetail) => void) {
  const detail = ref<FaultRecordOpDetail>()
  const running = ref(false)
  const error = ref('')
  let timer: ReturnType<typeof setTimeout> | undefined
  let watchingId = ''
  // 每次开始轮询递增；只有最新一轮可以继续排下一次，避免请求在途时重复开始导致多条轮询并行
  let generation = 0
  let startedAt = 0

  function stop() {
    generation++
    if (timer) clearTimeout(timer)
    timer = undefined
    running.value = false
  }

  async function poll(gen: number) {
    const id = watchingId
    try {
      const d = await getFaultRecordOperation(id)
      if (gen !== generation) return
      detail.value = d
      if (isTerminal(d.status)) {
        stop()
        onFinished?.(d)
        return
      }
    } catch (e) {
      if (gen !== generation) return
      error.value = errText(e)
    }
    const interval = Date.now() - startedAt < POLL_FAST_PERIOD ? POLL_FAST_INTERVAL : POLL_SLOW_INTERVAL
    timer = setTimeout(poll, interval, gen)
  }

  /** 查看某个已有操作（如从历史中选择），未结束时继续轮询；对正在轮询的同一操作重复调用不会重新开始 */
  function watch(id: string) {
    if (id === watchingId && running.value) return
    stop()
    watchingId = id
    error.value = ''
    running.value = true
    startedAt = Date.now()
    poll(generation)
  }

  async function start(req: FaultRecordCreateReq) {
    error.value = ''
    detail.value = undefined
    const { id } = await createFaultRecordOperation(req)
    watch(id)
    return id
  }

  async function cancel() {
    if (!detail.value) return
    await cancelFaultRecordOperation(detail.value.id)
  }

  onBeforeUnmount(stop)

  return { detail, running, error, start, watch, cancel, stop }
}