export async function PeerConnection(media: string) {
  const pc = new RTCPeerConnection({
    iceServers: [{ urls: 'stun:stun.l.google.com:19302' }],
  })

  const localTracks = []

  if (/camera|microphone/.test(media)) {
    const tracks = await getMediaTracks('user', {
      video: media.indexOf('camera') >= 0,
      audio: media.indexOf('microphone') >= 0,
    })
    tracks.forEach((track) => {
      pc.addTransceiver(track, { direction: 'sendonly' })
      if (track.kind === 'video') localTracks.push(track)
    })
  }

  if (media.indexOf('display') >= 0) {
    const tracks = await getMediaTracks('display', {
      video: true,
      audio: media.indexOf('speaker') >= 0,
    })
    tracks.forEach((track) => {
      pc.addTransceiver(track, { direction: 'sendonly' })
      if (track.kind === 'video') localTracks.push(track)
    })
  }

  if (/video|audio/.test(media)) {
    const tracks = ['video', 'audio']
      .filter((kind) => media.indexOf(kind) >= 0)
      .map((kind) => pc.addTransceiver(kind, { direction: 'recvonly' }).receiver.track)
    localTracks.push(...tracks)
  }

  return { pc, localTracks }
}

export async function getMediaTracks(media: string, constraints?: MediaStreamConstraints) {
  try {
    const stream =
      media === 'user'
        ? await navigator.mediaDevices.getUserMedia(constraints)
        : await navigator.mediaDevices.getDisplayMedia(constraints)
    return stream.getTracks()
  } catch (e) {
    console.warn(e)
    return []
  }
}

export async function connect(url: string, media: string) {
  const { pc, localTracks } = await PeerConnection(media)

  let ws = new WebSocket('ws' + url.toString().substring(4))

  ws.onopen = function () {
    pc.addEventListener('icecandidate', (ev) => {
      if (!ev.candidate) return
      const msg = { type: 'webrtc/candidate', value: ev.candidate.candidate }
      ws.send(JSON.stringify(msg))
    })

    pc.createOffer()
      .then((offer) => pc.setLocalDescription(offer))
      .then(() => {
        const msg = { type: 'webrtc/offer', value: pc.localDescription?.sdp }
        ws.send(JSON.stringify(msg))
      })
  }

  ws.onmessage = function (ev) {
    const msg = JSON.parse(ev.data)
    if (msg.type === 'webrtc/candidate') {
      pc.addIceCandidate({ candidate: msg.value, sdpMid: '0' })
    } else if (msg.type === 'webrtc/answer') {
      pc.setRemoteDescription({ type: 'answer', sdp: msg.value })
    }
  }

  ws.onerror = function (ev) {
    console.log({ ev })
  }

  ws.onclose = function () {
    setTimeout(function () {
      var ws2 = new WebSocket(ws.url)
      ws2.onopen = ws.onopen
      ws2.onmessage = ws.onmessage
      ws2.onclose = ws.onclose
      ws2.onerror = ws.onerror
      ws = ws2
    }, 2000)
  }

  return new MediaStream(localTracks)
}