/**
 * @websocket
 * @param url
 * @param onOpen
 * @param onMessage
 * @param onClose
 * @param onError
 * @param heart
 * @param isReconnect
 * @returns {WebSocket}
 * @private
 */
const _webSocket = (
  {
    url,
    onOpen,
    onMessage,
    onClose,
    onError,
    heart,
    isReconnect
  }
) => {
  if (!window.WebSocket) {
    throw new Error('您的浏览器不支持WebSocket')
  }
  let isConnected = false // 设定已链接webSocket标记
  let ws = null// websocket对象
  let heartTimer = null
  let _heart = {
    timer: 3000,
    message: ''
  }
  if (heart) {
    if (typeof heart === 'object' && Object.keys(heart).length > 0) {
      _heart = { ..._heart, ...heart }
    }
  } else {
    _heart = null
  }
  // 创建并链接webSocket
  const connect = () => {
    // 如果未链接webSocket，则创建一个新的webSocket
    if (!isConnected) {
      const wsUrl = `${process.env.VUE_APP_API_WS}${url}`
      ws = new WebSocket(wsUrl)
      isConnected = true
    }
  }
  // 向后台发送心跳消息
  const heartCheck = () => {
    ws.send(JSON.stringify(_heart.message))
  }
  // 初始化事件回调函数
  const initEventHandle = () => {
    ws.addEventListener('open', (e) => {
      if (_heart) {
        heartCheck()
      }
      // 如果传入了函数，执行onOpen
      if (!onOpen) {
        return false
      } else {
        onOpen(e, ws)
      }
    })
    ws.addEventListener('message', (e) => {
      if (!e) {
        console.log('get nothing from service')
        return false
      } else {
        // 如果获取到后台消息，则timer毫秒后再次发起心跳请求给后台，检测是否断连
        if (_heart) {
          heartTimer = setTimeout(
            () => {
              if (isConnected) {
                heartCheck()
              }
            },
            _heart.timer
          )
        }
      }
      // 如果传入了函数，执行onMessage
      if (!onMessage) {
        return false
      } else {
        onMessage(e)
      }
    })
    ws.addEventListener('close', (e) => {
      if (heartTimer) {
        clearTimeout(heartTimer)
        heartTimer = null
      }
      // 如果传入了函数，执行onClose
      if (!onClose) {
        return false
      } else {
        onClose(e)
      }
    })
    ws.addEventListener('error', (e) => {
      if (!onError) {
        return false
      } else {
        onError(e)
      }
      if (isReconnect) {
        // 如果断开立即重连标志为true
        // 重新链接webSocket
        connect()
      } else {
        if (heartTimer) {
          clearTimeout(heartTimer)
          heartTimer = null
        }
      }
    })
  }
  // 1.创建并链接webSocket
  connect()
  // 2.初始化事件回调函数
  initEventHandle()
  // 3.返回
  return ws
}

export default _webSocket

export { _webSocket }