import { useEffect, useMemo } from 'react'
import { type RoomMeta, useMessagePipeline, useRoomMeta } from '../model/message-pipeline'

const MAX_WATCHED = 24

export interface WatchedRoom {
  id: string
  name: string
}

/**
 * 为侧栏里的房间建立后台订阅：不在当前房间的消息也能进 pipeline，
 * 并携带名称与跳转地址供 toast 使用。
 */
export function RoomWatcher({
  spaceName,
  rooms,
  dms,
  activeRoomId,
}: {
  spaceName: string
  rooms: WatchedRoom[]
  dms: WatchedRoom[]
  activeRoomId: string | null
}) {
  const api = useMessagePipeline()

  const meta = useMemo(() => {
    const out: Record<string, RoomMeta> = {}
    for (const room of rooms)
      out[room.id] = {
        name: room.name,
        href: spaceName ? `/app/${spaceName}/chat/${room.id}` : `/app/@me/chat/${room.id}`,
      }
    for (const dm of dms) out[dm.id] = { name: dm.name, href: `/app/@me/chat/${dm.id}` }
    return out
  }, [rooms, dms, spaceName])

  useRoomMeta(meta)

  const ids = useMemo(() => [...rooms, ...dms].slice(0, MAX_WATCHED).map((room) => room.id), [rooms, dms])

  useEffect(() => {
    const releases = ids.map((id) => api.watch(id))
    return () => {
      for (const release of releases) release()
    }
  }, [api, ids])

  useEffect(() => {
    api.activate(activeRoomId)
    return () => api.activate(null)
  }, [api, activeRoomId])

  return null
}