import { ClientRequest } from 'http'

import { EventEmitter } from 'events'

export class RequestTimgingsMeasurer extends EventEmitter {
  public static new(options: any) {
    return new RequestTimgingsMeasurer(options)
  }

  private readonly enable: boolean
  private readonly timings: any
  private readonly interval: number
  private readonly waitingTime: number
  private timerStarted: boolean
  private intervalId: any
  private timeoutId: any

  private e: Error = null

  public constructor(options: any) {
    super()

    this.timings = {
      // start: 0,
      // lookup: -1,
      // connect: -1,
      // ready: -1,
      // waiting: -1,
      // download: -1,
      // end: -1
    }

    this.e = null
    this.enable = options.enable === true
    this.timerStarted = false
    this.intervalId = null
    this.timeoutId = null

    this.waitingTime = options.waitingTime || 1000
    this.interval = options.interval || 200
  }

  /* istanbul ignore next */
  public measure(clientRequest: ClientRequest) {
    if (!this.enable) {
      return
    }

    this.startTimer()
    const timings = this.timings

    timings.start = Date.now()

    clientRequest
      .once('response', message => {
        timings.response = Date.now()

        timings.waiting = Date.now() - timings.start

        message.once('end', () => {
          timings.socket = timings.socket || 0
          // timings.lookup = timings.lookup || timings.socket
          // timings.connect = timings.connect || timings.lookup
          timings.download = Date.now() - timings.response
          timings.end = Date.now() - timings.start
          this.stopTimer('end')
        })
      })
      .once('socket', socket => {
        timings.socket = Date.now() - timings.start

        const onlookup = () => {
          this.timings.lookup = Date.now() - this.timings.start
        }
        const onconnect = () => {
          this.timings.connect = Date.now() - this.timings.start
        }
        const onready = () => {
          this.timings.ready = Date.now() - this.timings.start
        }

        if (socket.connecting) {
          socket.once('lookup', onlookup)
          socket.once('connect', onconnect)
          socket.once('ready', onready)
          socket.once('error', e => {
            socket.off('lookup', onlookup)
            socket.off('connect', onconnect)
            socket.off('ready', onready)
            this.e = e
            this.timings.error = Date.now() - this.timings.start
            this.stopTimer(`ee:${e.message}`)
          })
        } else {
          this.timings.lookup = -1
          this.timings.connect = -1
          this.timings.ready = -1
        }
        // socket.once('data', () => {})
        // socket.once('drain', () => {})
        // socket.once('end', () => {
        //   this.stopTimer('end')
        // })
        // socket.once('timeout', () => {
        //   this.timings.timeout = Date.now() - this.timings.start
        // })
      })
      .once('error', (e: Error) => {
        this.stopTimer(`ee:${e.message}`)
      })
  }

  /* istanbul ignore next */
  private startTimer() {
    if (!this.enable) {
      return
    }

    if (this.timerStarted) {
      return
    }

    this.timerStarted = true
    this.intervalId = null
    this.timeoutId = setTimeout(() => {
      this.process('inprogress')
      this.intervalId = setInterval(() => {
        this.process('inprogress')
      }, this.interval)
    }, this.waitingTime)
  }

  /* istanbul ignore next */
  private stopTimer(reason: string) {
    // if (!this.enable) {
    //   return
    // }

    // if (!this.timerStarted) {
    //   return
    // }

    this.timerStarted = false

    clearTimeout(this.timeoutId)
    clearInterval(this.intervalId)
    this.process(reason)
  }

  /* istanbul ignore next */
  private process(reason: string) {
    this.emit('progress', { ...this.timings }, reason)
  }
}