/**
 * 管理后台 WebRTC 开播（需登录 token，与 /api/web/live/ws?role=publish&token= 一致）
 */
const apiBase = (import.meta.env.VITE_API_BASE || '').replace(/\/$/, '')

function liveWsURLPublish(token) {
  const path = `/api/web/live/ws?role=publish&token=${encodeURIComponent(token)}`
  if (apiBase) {
    const base = apiBase.replace(/\/$/, '')
    const wsOrigin = base.replace(/^https:/i, 'wss:').replace(/^http:/i, 'ws:')
    return `${wsOrigin}${path}`
  }
  const proto = window.location.protocol === 'https:' ? 'wss:' : 'ws:'
  return `${proto}//${window.location.host}${path}`
}

const defaultIce = [{ urls: 'stun:stun.l.google.com:19302' }]

/** 将 getUserMedia 异常转为中文说明（含 Edge 英文 “Could not start video source”） */
function humanizeGetUserMediaError(err) {
  const name = err && err.name
  const raw = ((err && err.message) || '').toLowerCase()
  if (name === 'NotAllowedError' || name === 'PermissionDeniedError') {
    return '已拒绝摄像头或麦克风权限：在浏览器地址栏左侧允许摄像头与麦克风，并确认本页为 HTTPS。'
  }
  if (name === 'NotFoundError' || name === 'DevicesNotFoundError') {
    return '未检测到摄像头，请检查是否已接入设备或被系统禁用。'
  }
  if (
    name === 'NotReadableError' ||
    raw.includes('could not start video source') ||
    raw.includes('failed to start video source') ||
    raw.includes('video source')
  ) {
    return '无法启动摄像头：可能被 Zoom、Teams、腾讯会议、OBS 等占用；或在 Windows「设置 → 隐私和安全性 → 相机」中未允许浏览器/桌面应用访问。请关闭占用软件后刷新页面重试。'
  }
  if (name === 'OverconstrainedError') {
    return '摄像头不满足当前参数约束，请换用其他摄像头或更新驱动。'
  }
  if (name === 'AbortError') {
    return '打开摄像头被系统中断，请重试。'
  }
  return (err && err.message) || '无法打开摄像头'
}

/**
 * @param {object} opts
 * @param {string} opts.token 管理员 JWT
 * @param {(s: string) => void} [opts.onStatus]
 * @param {(stream: MediaStream) => void} [opts.onLocalStream]
 */
export function startPublishing(opts = {}) {
  const { token = '', onStatus = () => {}, onLocalStream = () => {} } = opts
  if (!token) {
    onStatus('未登录，无法开播')
    return { stop: () => {} }
  }

  const wsUrl = liveWsURLPublish(token)
  const ws = new WebSocket(wsUrl)
  const pc = new RTCPeerConnection({ iceServers: defaultIce })
  let stream = null
  /** 本地主动 stop / 摄像头失败关闭，避免 onclose 覆盖真实错误提示 */
  let closedByLocal = false

  const send = (o) => {
    if (ws.readyState === WebSocket.OPEN) ws.send(JSON.stringify(o))
  }

  pc.onicecandidate = (e) => {
    if (e.candidate) send({ type: 'ice', candidate: e.candidate.toJSON() })
  }

  ws.onopen = async () => {
    onStatus('信令已连接，正在采集摄像头…')
    try {
      // 后台多为 PC：不要用 facingMode:'user'，部分机器会直接导致 “Could not start video source”
      stream = await navigator.mediaDevices.getUserMedia({ video: true, audio: true })
      onLocalStream(stream)
      stream.getTracks().forEach((t) => pc.addTrack(t, stream))
      const offer = await pc.createOffer()
      await pc.setLocalDescription(offer)
      send({ type: 'offer', sdp: offer.sdp })
      onStatus('已发起推流协商，等待服务端应答…')
    } catch (err) {
      onStatus(humanizeGetUserMediaError(err))
      stop()
    }
  }

  ws.onmessage = async (ev) => {
    let msg
    try {
      msg = JSON.parse(ev.data)
    } catch {
      return
    }
    if (msg.type === 'answer' && msg.sdp) {
      try {
        await pc.setRemoteDescription({ type: 'answer', sdp: msg.sdp })
        onStatus('直播中（请勿关闭本页；关闭即结束本场）')
      } catch (e) {
        onStatus(e.message || '设置远端描述失败')
      }
    }
    if (msg.type === 'ice' && msg.candidate) {
      try {
        await pc.addIceCandidate(msg.candidate)
      } catch (_) {}
    }
    if (msg.type === 'error') {
      onStatus(msg.message || '服务端错误')
    }
  }

  ws.onerror = () => {
    if (!closedByLocal) {
      onStatus('信令连接失败（请确认已登录且 Nginx 已配置 WebSocket）')
    }
  }
  ws.onclose = () => {
    if (closedByLocal) return
    onStatus('信令已断开：服务端关闭连接或网络中断。若刚能连上即断，请查服务端日志或配置 TURN（LIVE_ICE_SERVERS）。')
  }

  function stop() {
    closedByLocal = true
    try {
      ws.close()
    } catch (_) {}
    pc.getSenders().forEach((s) => {
      try {
        s.track?.stop()
      } catch (_) {}
    })
    pc.close()
    stream?.getTracks().forEach((t) => t.stop())
  }

  return { pc, ws, stop }
}