/**
 * Everything a room needs besides its transcript: the authoritative room row,
 * the member directory (names, avatars, @-mention targets), online presence,
 * the pin list, the thread index and the space's custom emojis.
 *
 * These are five independent reads with different failure modes, so each one
 * keeps its own state and the room stays usable when any of them is missing:
 * a private room whose member list is forbidden still chats, an unreachable
 * presence endpoint just leaves every dot grey.
 */

import {
  type ChatMessage,
  type CustomEmoji,
  getRoom,
  listPins,
  listRoomMembers,
  listRoomThreads,
  listSpaceEmojis,
  listSpacePresences,
  type Presence,
  type RoomBrief,
  type RoomMember,
  type ThreadBrief,
} from '@app/domains/chat/model'
import { t } from '@app/i18n'
import { type AsyncState, roomKey, spaceEmojisKey, useAsync } from '@app/lib'
import { useWsUserEvents } from '@app/services/realtime'
import { useCallback, useEffect, useMemo, useState } from 'react'

export interface RoomData {
  /** `GET /chat/rooms/{id}` — the room as the server sees it right now. */
  room: AsyncState<RoomBrief | undefined>
  members: AsyncState<RoomMember[]>
  pins: AsyncState<ChatMessage[]>
  threads: AsyncState<ThreadBrief[]>
  /** Empty outside a space (the personal `@me` scope has no presence list). */
  presences: AsyncState<Presence[]>
  emojis: AsyncState<CustomEmoji[]>
  reload: () => void
  /** Thread indexed by its root message, so a row knows its own topic. */
  threadOf: (messageId: string) => ThreadBrief | undefined
  /** Display name for a user id, resolved from the room's member list. */
  nameOf: (userId: number | null | undefined) => string
}

export interface UseRoomDataOptions {
  roomId: string
  /** Personal scope (`@me`) has no space-scoped presence/emoji endpoints. */
  spaceName?: string
  enabled?: boolean
  /** Bumped by live `room_updated` / `thread_updated` traffic. */
  version?: number
}

export function useRoomData({ roomId, spaceName, enabled = true, version = 0 }: UseRoomDataOptions): RoomData {
  const [reloadKey, setReloadKey] = useState(0)
  const gate = enabled && Boolean(roomId)
  // `version` rides along with the dependency list: live traffic that changes
  // room state (a pin by someone else, a new thread) refreshes the side data
  // without the user having to reopen the panel. Every read is local-first:
  // reopening a room paints the stored payload while the refresh runs.
  const deps = [gate ? roomId : '', gate, version, reloadKey]
  const room = useAsync(() => (gate ? getRoom(roomId) : Promise.resolve(undefined)), deps, {
    cacheKey: gate ? roomKey(roomId, 'room') : null,
  })
  const members = useAsync(() => (gate ? listRoomMembers(spaceName ?? '', roomId).catch(() => []) : Promise.resolve([])), deps, {
    cacheKey: gate ? roomKey(roomId, 'members') : null,
  })
  const pins = useAsync(() => (gate ? listPins(roomId).catch(() => []) : Promise.resolve([])), deps, {
    cacheKey: gate ? roomKey(roomId, 'pins') : null,
  })
  const threads = useAsync(() => (gate ? listRoomThreads(roomId).catch(() => []) : Promise.resolve([])), deps, {
    cacheKey: gate ? roomKey(roomId, 'threads') : null,
  })
  // Presence is live-only state: a stale online dot is worse than no dot.
  // 队友的在线变化没有广播通道（`presence` 事件只回发给本人），所以在标签页
  // 可见时每 30s 重拉一次，切回前台立刻补一次；隐藏时停表，不空转网络。
  const [presenceTick, setPresenceTick] = useState(0)
  const livePresence = gate && Boolean(spaceName) && spaceName !== '@me'
  useEffect(() => {
    if (!livePresence) return
    const tick = () => setPresenceTick((value) => value + 1)
    let timer: ReturnType<typeof setInterval> | undefined
    const start = () => {
      if (timer === undefined) timer = setInterval(tick, 30_000)
    }
    const stop = () => {
      if (timer !== undefined) {
        clearInterval(timer)
        timer = undefined
      }
    }
    const onVisibility = () => {
      if (document.visibilityState === 'visible') {
        tick()
        start()
      } else {
        stop()
      }
    }
    if (document.visibilityState === 'visible') start()
    document.addEventListener('visibilitychange', onVisibility)
    return () => {
      stop()
      document.removeEventListener('visibilitychange', onVisibility)
    }
  }, [livePresence])
  // 自己上线/改状态（`presence` 事件只回发给本人）时立即补拉一次：硬刷新直接
  // 进房间时，挂载那一刻 socket 可能还没连上，首屏的在线状态会短暂缺失。
  useWsUserEvents((event) => {
    if (event.kind === 'presence') setPresenceTick((value) => value + 1)
  })
  const presences = useAsync(
    () =>
      gate && spaceName && spaceName !== '@me' ? listSpacePresences(spaceName).catch(() => []) : Promise.resolve([]),
    [gate, spaceName, reloadKey, presenceTick],
  )
  const emojis = useAsync(
    () => (gate && spaceName && spaceName !== '@me' ? listSpaceEmojis(spaceName).catch(() => []) : Promise.resolve([])),
    [gate, spaceName, reloadKey],
    { cacheKey: gate && spaceName && spaceName !== '@me' ? spaceEmojisKey(spaceName) : null },
  )

  const reload = useCallback(() => setReloadKey((key) => key + 1), [])

  const byRoot = useMemo(() => {
    const map = new Map<string, ThreadBrief>()
    for (const thread of threads.data ?? []) map.set(thread.root_message_id, thread)
    return map
  }, [threads.data])

  const users = useMemo(() => {
    const map = new Map<number, string>()
    for (const member of members.data ?? []) {
      map.set(member.user.user_id, member.nick || member.user.display_name || member.user.username)
    }
    return map
  }, [members.data])

  const threadOf = useCallback((messageId: string) => byRoot.get(messageId), [byRoot])

  const nameOf = useCallback(
    (userId: number | null | undefined) => {
      if (!userId) return t('common.state.unknownUser')
      return users.get(userId) ?? t('shell.chat.userFallback', { id: String(userId).slice(0, 8) })
    },
    [users],
  )

  return { room, members, pins, threads, presences, emojis, reload, threadOf, nameOf }
}