/**
 * NOTE
 * The ./unread.ts API:
 *
 * - Provides a `checkUnread()` function to sync with the server,
 * - Periodically calls `checkUnread()`, and
 * - Caches the first page of notifications.
 *
 * IMPORTANT: This query uses ./unread.ts's cache as its first page,
 * IMPORTANT: which means the cache-freshness of this query is driven by the unread API.
 *
 * Follow these rules:
 *
 * 1. Call `checkUnread()` if you want to fetch latest in the background.
 * 2. Call `checkUnread({invalidate: true})` if you want latest to sync into this query's results immediately.
 * 3. Don't call this query's `refetch()` if you're trying to sync latest; call `checkUnread()` instead.
 */

import {AppBskyFeedDefs} from '@atproto/api'
import {
  useInfiniteQuery,
  InfiniteData,
  QueryKey,
  useQueryClient,
  QueryClient,
} from '@tanstack/react-query'
import {useModerationOpts} from '../preferences'
import {useUnreadNotificationsApi} from './unread'
import {fetchPage} from './util'
import {FeedPage} from './types'
import {useMutedThreads} from '#/state/muted-threads'

export type {NotificationType, FeedNotification, FeedPage} from './types'

const PAGE_SIZE = 30

type RQPageParam = string | undefined

export function RQKEY() {
  return ['notification-feed']
}

export function useNotificationFeedQuery(opts?: {enabled?: boolean}) {
  const queryClient = useQueryClient()
  const moderationOpts = useModerationOpts()
  const threadMutes = useMutedThreads()
  const unreads = useUnreadNotificationsApi()
  const enabled = opts?.enabled !== false

  return useInfiniteQuery<
    FeedPage,
    Error,
    InfiniteData<FeedPage>,
    QueryKey,
    RQPageParam
  >({
    queryKey: RQKEY(),
    async queryFn({pageParam}: {pageParam: RQPageParam}) {
      // for the first page, we check the cached page held by the unread-checker first
      if (!pageParam) {
        const cachedPage = unreads.getCachedUnreadPage()
        if (cachedPage) {
          return cachedPage
        }
      }
      // do a normal fetch
      return fetchPage({
        limit: PAGE_SIZE,
        cursor: pageParam,
        queryClient,
        moderationOpts,
        threadMutes,
      })
    },
    initialPageParam: undefined,
    getNextPageParam: lastPage => lastPage.cursor,
    enabled,
  })
}

/**
 * This helper is used by the post-thread placeholder function to
 * find a post in the query-data cache
 */
export function findPostInQueryData(
  queryClient: QueryClient,
  uri: string,
): AppBskyFeedDefs.PostView | undefined {
  const queryDatas = queryClient.getQueriesData<InfiniteData<FeedPage>>({
    queryKey: ['notification-feed'],
  })
  for (const [_queryKey, queryData] of queryDatas) {
    if (!queryData?.pages) {
      continue
    }
    for (const page of queryData?.pages) {
      for (const item of page.items) {
        if (item.subject?.uri === uri) {
          return item.subject
        }
      }
    }
  }
  return undefined
}