/**
 * Convert a netx REST apiUrl into the DSH alarm-subscribe WebSocket URL.
 * @param apiUrl - e.g. http://192.168.1.10:8890
 */

import {
  publishAlarmPushStatus,
  type AlarmPushPhase,
} from './alarm-push-status.ts'
import { alarmActionLabel, tHost } from './i18n.ts'

export function alarmSubscribeUrl(apiUrl: string): string {
  const trimmed = apiUrl.trim().replace(/\/$/, '')
  if (!trimmed) return ''
  let url: URL
  try {
    url = new URL(trimmed)
  } catch {
    return ''
  }
  url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:'
  url.pathname = '/v1/integrations/dsh-alarm/ws'
  url.search = ''
  url.hash = ''
  return url.toString()
}

export interface KeyAlarmPayload {
  action?: string
  alarm_key?: string
  notification_id?: string
  rule_label?: string
  rule_key?: string
  native_probable_cause?: string
  perceived_severity?: string
  time_created?: string
  object_name?: string
  ne_id?: string
  ne?: Record<string, string>
  [key: string]: unknown
}

/** Human-readable prompt for a sticky Netx Ops DSH session. */
export function formatAlarmPrompt(payload: KeyAlarmPayload, lang = 'zh'): string {
  const action = String(payload.action ?? '').trim().toLowerCase()
  const ne = payload.ne && typeof payload.ne === 'object' ? payload.ne : {}
  const host = String(ne.host_name ?? '').trim()
  const ip = String(ne.ip_address ?? '').trim()
  const neName = String(ne.ne_name ?? ne.user_label ?? '').trim()
  let device = host || neName || String(payload.ne_id ?? '').trim() || '-'
  if (ip) device = device === '-' ? ip : `${device} (${ip})`

  const label = String(
    payload.rule_label
      ?? payload.native_probable_cause
      ?? tHost('alarm.defaultLabel', lang),
  ).trim()
  return [
    `[NMS ${alarmActionLabel(action, lang)}] ${label}`,
    `${tHost('alarm.field.device', lang)}: ${device}`,
    `${tHost('alarm.field.object', lang)}: ${String(payload.object_name ?? '-').trim()}`,
    `${tHost('alarm.field.severity', lang)}: ${String(payload.perceived_severity ?? '-').trim()}`,
    `${tHost('alarm.field.cause', lang)}: ${String(payload.native_probable_cause ?? '-').trim()}`,
    `${tHost('alarm.field.time', lang)}: ${String(payload.time_created ?? '-').trim()}`,
    `notificationId: ${String(payload.notification_id ?? '-').trim()}`,
    `alarm_key: ${String(payload.alarm_key ?? '-').trim()}`,
    '',
    tHost('alarm.analyzeHint', lang),
  ].join('\n')
}

export type AlarmHandler = (payload: KeyAlarmPayload) => void | Promise<void>

export interface AlarmPushClientOptions {
  apiUrl: string
  token: string
  logger?: {
    info?: (...args: unknown[]) => void
    warn?: (...args: unknown[]) => void
    error?: (...args: unknown[]) => void
  }
  onAlarm: AlarmHandler
  /** Reconnect delay base in ms (default 2000). */
  reconnectMs?: number
  /** WebSocket constructor override (tests). */
  WebSocketImpl?: typeof WebSocket
}

function setPhase(
  phase: AlarmPushPhase,
  wsUrl: string,
  extra: { detail?: string, lastError?: string | null, lastConnectedAt?: number | null } = {},
): void {
  publishAlarmPushStatus({
    phase,
    enabled: true,
    wsUrl,
    detail: extra.detail ?? '',
    lastError: extra.lastError === undefined ? null : extra.lastError,
    ...(extra.lastConnectedAt !== undefined ? { lastConnectedAt: extra.lastConnectedAt } : {}),
  })
}

/**
 * Dial out to netx's fixed-IP alarm hub and forward `netx.alarm` events.
 * @returns disposer that closes the socket and cancels reconnect.
 */
export function startAlarmPushClient(options: AlarmPushClientOptions): () => void {
  const log = options.logger ?? console
  const wsUrl = alarmSubscribeUrl(options.apiUrl)
  const token = options.token.trim()
  if (!wsUrl || !token) {
    log.warn?.('netxops alarm-push: missing apiUrl or token — not connecting')
    setPhase('error', wsUrl, {
      detail: 'missing_url_or_token',
      lastError: 'missing apiUrl or token',
    })
    return () => {}
  }

  const WS = options.WebSocketImpl ?? globalThis.WebSocket
  if (typeof WS !== 'function') {
    log.error?.('netxops alarm-push: WebSocket is unavailable in this runtime')
    setPhase('error', wsUrl, {
      detail: 'websocket_unavailable',
      lastError: 'WebSocket unavailable',
    })
    return () => {}
  }

  let closed = false
  /** After auth-fail, do not reconnect until the client is disposed/restarted. */
  let haltReconnect = false
  /** Only forward alarms after a successful auth-ok on the current socket. */
  let subscribed = false
  let socket: WebSocket | null = null
  let reconnectTimer: ReturnType<typeof setTimeout> | undefined
  let attempt = 0
  const baseDelay = Math.max(500, options.reconnectMs ?? 2_000)

  const clearReconnect = (): void => {
    if (reconnectTimer !== undefined) {
      clearTimeout(reconnectTimer)
      reconnectTimer = undefined
    }
  }

  const scheduleReconnect = (reason: string): void => {
    if (closed || haltReconnect) return
    clearReconnect()
    const delay = Math.min(60_000, baseDelay * (2 ** Math.min(attempt, 5)))
    attempt += 1
    setPhase('reconnecting', wsUrl, {
      detail: `retry_in_${delay}ms`,
      lastError: reason,
    })
    reconnectTimer = setTimeout(() => { connect() }, delay)
  }

  const connect = (): void => {
    if (closed || haltReconnect) return
    clearReconnect()
    subscribed = false
    setPhase(attempt > 0 ? 'reconnecting' : 'connecting', wsUrl, { detail: 'dialing' })
    try {
      socket = new WS(wsUrl)
    } catch (error) {
      const message = error instanceof Error ? error.message : String(error)
      log.warn?.('netxops alarm-push: connect failed:', error)
      scheduleReconnect(message)
      return
    }

    socket.addEventListener('open', () => {
      setPhase('authenticating', wsUrl, { detail: 'auth' })
      let clientLabel = 'netxops'
      try {
        // Node / Bun hosts: include hostname so NetX hub can list multi-DSH links.
        const env = typeof process !== 'undefined' ? process.env : undefined
        const hostname = env?.HOSTNAME || env?.COMPUTERNAME
        if (typeof hostname === 'string' && hostname.trim()) {
          clientLabel = `netxops@${hostname.trim()}`
        }
      } catch {
        // browser / restricted runtime — keep generic label
      }
      socket?.send(JSON.stringify({ type: 'auth', token, client: clientLabel }))
    })

    socket.addEventListener('message', (event) => {
      let msg: Record<string, unknown>
      try {
        msg = JSON.parse(String(event.data)) as Record<string, unknown>
      } catch {
        return
      }
      const type = String(msg.type ?? '').toLowerCase()
      if (type === 'auth-ok') {
        attempt = 0
        subscribed = true
        const now = Date.now()
        setPhase('connected', wsUrl, {
          detail: String(msg.user ?? 'ok'),
          lastError: null,
          lastConnectedAt: now,
        })
        log.info?.('netxops alarm-push: subscribed to %s', wsUrl)
        return
      }
      if (type === 'auth-fail') {
        const err = String(msg.error ?? 'auth_failed')
        log.error?.('netxops alarm-push: auth failed (%s) — not reconnecting until settings/token change', err)
        subscribed = false
        haltReconnect = true
        clearReconnect()
        setPhase('auth_failed', wsUrl, { detail: err, lastError: err })
        try {
          socket?.close()
        } catch {
          // ignore
        }
        return
      }
      if (type === 'pong') return
      if (type === 'event' && String(msg.event ?? '') === 'netx.alarm') {
        if (!subscribed) {
          log.warn?.('netxops alarm-push: ignoring alarm before auth-ok')
          return
        }
        const payload = msg.payload && typeof msg.payload === 'object'
          ? msg.payload as KeyAlarmPayload
          : {}
        void Promise.resolve(options.onAlarm(payload)).catch((error) => {
          log.warn?.('netxops alarm-push: handler failed:', error)
        })
      }
    })

    socket.addEventListener('close', () => {
      socket = null
      subscribed = false
      if (!closed && !haltReconnect) scheduleReconnect('socket_closed')
    })

    socket.addEventListener('error', () => {
      // close handler schedules reconnect
    })
  }

  const pingTimer = setInterval(() => {
    if (socket && socket.readyState === WS.OPEN) {
      try {
        socket.send(JSON.stringify({ type: 'ping', ts: new Date().toISOString() }))
      } catch {
        // ignore
      }
    }
  }, 25_000)

  connect()

  return () => {
    closed = true
    clearReconnect()
    clearInterval(pingTimer)
    try {
      socket?.close()
    } catch {
      // ignore
    }
    socket = null
  }
}