import logger from '@/lib/logger'
import { ExtendedKind } from '@/constants'
import { getFavoritesFeedRelayUrls } from '@/lib/favorites-feed-relays'
import {
  readRelayPulseActiveNpubsCache,
  writeRelayPulseActiveNpubsCache
} from '@/lib/relay-pulse-active-npubs-cache'
import { hexPubkeysEqual, normalizeHexPubkey, userIdToPubkey } from '@/lib/pubkey'
import { getPubkeysFromPTags } from '@/lib/tag'
import { useFavoriteRelays } from '@/providers/FavoriteRelaysProvider'
import { useNostr } from '@/providers/NostrProvider'
import { queryService, replaceableEventService } from '@/services/client.service'
import indexedDb from '@/services/indexed-db.service'
import storage from '@/services/local-storage.service'
import type { Event } from 'nostr-tools'
import { kinds } from 'nostr-tools'
import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
import {
  FavoriteRelaysActivityContext,
  type TFavoriteRelaysActivityContext
} from './favorite-relays-activity-context'

const ACTIVE_WINDOW_SEC = 3600
const FETCH_RETRY_DELAY_MS = 2500
/** Wall-clock cadence while the tab is visible */
const POLL_INTERVAL_MS = 60 * 60 * 1000
/** Event cap for relay pulse query. This is event-count (not author-count): keep high enough for >120 active npubs. */
const REQ_LIMIT = 500
/** Keep relay pulse focused on note-like activity to avoid expensive all-kind signature verification bursts. */
const ACTIVE_PULSE_KINDS = [
  kinds.ShortTextNote,
  kinds.Repost,
  kinds.LongFormArticle,
  kinds.Highlights,
  ExtendedKind.DISCUSSION,
  ExtendedKind.PICTURE,
  ExtendedKind.VIDEO,
  ExtendedKind.SHORT_VIDEO,
  ExtendedKind.COMMENT,
  ExtendedKind.GENERIC_REPOST
] as number[]

function aggregatePubkeysByRecency(events: { pubkey: string; created_at: number }[]): string[] {
  const lastByPk = new Map<string, number>()
  for (const e of events) {
    const prev = lastByPk.get(e.pubkey) ?? 0
    if (e.created_at > prev) lastByPk.set(e.pubkey, e.created_at)
  }
  return [...lastByPk.entries()]
    .sort((a, b) => b[1] - a[1])
    .map(([pk]) => pk)
}

function partitionByFollows(orderedPubkeys: string[], followings: string[]) {
  if (followings.length === 0) {
    return {
      followPubkeys: [] as string[],
      otherPubkeys: orderedPubkeys,
      followCount: 0,
      otherCount: orderedPubkeys.length
    }
  }
  const followSet = new Set(
    followings
      .map((p) => userIdToPubkey(p))
      .filter((hex): hex is string => !!hex && /^[0-9a-f]{64}$/i.test(hex))
      .map((hex) => hex.toLowerCase())
  )
  const followPubkeys: string[] = []
  const otherPubkeys: string[] = []
  for (const pk of orderedPubkeys) {
    const hex = normalizeHexPubkey(pk)
    if (hex.length === 64 && followSet.has(hex)) followPubkeys.push(pk)
    else otherPubkeys.push(pk)
  }
  return {
    followPubkeys,
    otherPubkeys,
    followCount: followPubkeys.length,
    otherCount: otherPubkeys.length
  }
}

export function FavoriteRelaysActivityProvider({ children }: { children: React.ReactNode }) {
  const { favoriteRelays, blockedRelays } = useFavoriteRelays()
  const { pubkey: viewerPubkey, followListEvent } = useNostr()
  const followings = useMemo(
    () => (followListEvent ? getPubkeysFromPTags(followListEvent.tags) : []),
    [followListEvent]
  )
  const [orderedPubkeys, setOrderedPubkeys] = useState<string[]>([])
  const [loading, setLoading] = useState(false)
  const [relayActivityReady, setRelayActivityReady] = useState(false)
  const [lastFetchedAtMs, setLastFetchedAtMs] = useState<number | null>(null)
  const [profileKind0ByPubkey, setProfileKind0ByPubkey] = useState<Record<string, Event>>({})
  const [profilesLoading, setProfilesLoading] = useState(false)
  const [activeNpubsDrawerOpen, setActiveNpubsDrawerOpen] = useState(false)
  const [fallbackFollowings, setFallbackFollowings] = useState<string[]>([])
  const lastCompletedFetchAtRef = useRef(Date.now())
  /** Nostr pubkey hydrates async after reload; storage already has current account (init before React mount). */
  const viewerForPulseCache = viewerPubkey ?? storage.getCurrentAccount()?.pubkey ?? null
  const orderedPubkeysRef = useRef<string[]>([])
  orderedPubkeysRef.current = orderedPubkeys
  /** After restoring from disk, ignore the first empty network result (timeouts / slow relays), then behave normally. */
  const skipFirstEmptyNetworkOverwriteRef = useRef(false)
  const relayKey = useMemo(
    () => getFavoritesFeedRelayUrls(favoriteRelays, blockedRelays).join('\n'),
    [favoriteRelays, blockedRelays]
  )

  const fetchActive = useCallback(
    async (useDefaultRelays = false) => {
      const cacheViewer = viewerPubkey ?? storage.getCurrentAccount()?.pubkey ?? null
      const urls = useDefaultRelays
        ? getFavoritesFeedRelayUrls([], blockedRelays)
        : getFavoritesFeedRelayUrls(favoriteRelays, blockedRelays)
      if (urls.length === 0) {
        setLoading(false)
        setRelayActivityReady(true)
        const now = Date.now()
        setOrderedPubkeys([])
        lastCompletedFetchAtRef.current = now
        setLastFetchedAtMs(now)
        writeRelayPulseActiveNpubsCache({
          relayKey,
          viewerPubkey: cacheViewer,
          orderedPubkeys: [],
          lastFetchedAtMs: now
        })
        return
      }
      setLoading(true)
      const since = Math.floor(Date.now() / 1000) - ACTIVE_WINDOW_SEC
      try {
        const events = await queryService.fetchEvents(
          urls,
          { since, limit: REQ_LIMIT, kinds: [...ACTIVE_PULSE_KINDS] },
          {
            firstRelayResultGraceMs: false,
            eoseTimeout: 1800,
            globalTimeout: 14_000
          }
        )
        const now = Date.now()
        const nextPubkeys = aggregatePubkeysByRecency(events)
        const prev = orderedPubkeysRef.current
        if (
          skipFirstEmptyNetworkOverwriteRef.current &&
          nextPubkeys.length === 0 &&
          prev.length > 0
        ) {
          skipFirstEmptyNetworkOverwriteRef.current = false
          logger.debug('[FavoriteRelaysActivity] kept relay pulse from cache; first fetch returned empty')
        } else {
          skipFirstEmptyNetworkOverwriteRef.current = false
          setOrderedPubkeys(nextPubkeys)
          lastCompletedFetchAtRef.current = now
          setLastFetchedAtMs(now)
          writeRelayPulseActiveNpubsCache({
            relayKey,
            viewerPubkey: cacheViewer,
            orderedPubkeys: nextPubkeys,
            lastFetchedAtMs: now
          })
        }
      } catch (error) {
        logger.debug('[FavoriteRelaysActivity] fetch failed', { error, useDefaultRelays })
        if (!useDefaultRelays && favoriteRelays.length > 0) {
          setTimeout(() => void fetchRef.current(true), FETCH_RETRY_DELAY_MS)
        }
      } finally {
        setLoading(false)
        setRelayActivityReady(true)
      }
    },
    [favoriteRelays, blockedRelays, relayKey, viewerPubkey]
  )

  const fetchRef = useRef(fetchActive)
  fetchRef.current = fetchActive

  /** Reset pulse state when account or relay set changes so we show loading until fresh data. */
  const resetForRefetch = useCallback(() => {
    skipFirstEmptyNetworkOverwriteRef.current = false
    setRelayActivityReady(false)
    setOrderedPubkeys([])
    setProfileKind0ByPubkey({})
  }, [])

  /** Initial fetch on mount and when relay set changes. Use stale-while-revalidate: keep previous
   * data visible until new fetch completes instead of clearing and showing skeleton. */
  const prevRelayKeyRef = useRef<string | undefined>(undefined)
  useEffect(() => {
    if (prevRelayKeyRef.current === undefined) {
      prevRelayKeyRef.current = relayKey
      void fetchRef.current()
      return
    }
    if (prevRelayKeyRef.current === relayKey) return
    prevRelayKeyRef.current = relayKey
    void fetchRef.current()
  }, [relayKey])

  /** Logged-in user changed — refetch for the new account. Follow list changes update partition via useMemo. */
  const prevViewerRef = useRef<string | undefined>(undefined)
  useEffect(() => {
    if (prevViewerRef.current !== undefined && prevViewerRef.current !== viewerPubkey) {
      resetForRefetch()
      setFallbackFollowings([])
      void fetchRef.current()
    }
    prevViewerRef.current = viewerPubkey ?? undefined
  }, [viewerPubkey, resetForRefetch])

  /** Restore last successful relay-pulse author list from localStorage (same relay set + viewer). */
  useEffect(() => {
    const row = readRelayPulseActiveNpubsCache(relayKey, viewerForPulseCache)
    if (!row) return
    setOrderedPubkeys(row.orderedPubkeys)
    setLastFetchedAtMs(row.lastFetchedAtMs)
    setRelayActivityReady(true)
    lastCompletedFetchAtRef.current = row.lastFetchedAtMs
    skipFirstEmptyNetworkOverwriteRef.current = row.orderedPubkeys.length > 0
  }, [relayKey, viewerForPulseCache])

  /** When follow list from context is empty but we have a logged-in viewer, try IndexedDB cache.
   * Fixes race where pulse data arrives before NostrProvider has hydrated follow list from cache. */
  useEffect(() => {
    if (!viewerPubkey || followings.length > 0) {
      setFallbackFollowings([])
      return
    }
    let cancelled = false
    indexedDb
      .getReplaceableEvent(viewerPubkey, kinds.Contacts)
      .then((evt) => {
        if (cancelled || !evt) return
        setFallbackFollowings(getPubkeysFromPTags(evt.tags))
      })
      .catch(() => {})
    return () => {
      cancelled = true
    }
  }, [viewerPubkey, followings.length])

  /** While the document is visible: poll once per hour; when returning after a long background, catch up if due. */
  useEffect(() => {
    let intervalId: ReturnType<typeof setInterval> | undefined

    const runTick = () => {
      void fetchRef.current()
    }

    const syncPolling = () => {
      if (document.visibilityState !== 'visible') {
        if (intervalId !== undefined) {
          clearInterval(intervalId)
          intervalId = undefined
        }
        return
      }
      if (intervalId === undefined) {
        intervalId = setInterval(runTick, POLL_INTERVAL_MS)
      }
      if (Date.now() - lastCompletedFetchAtRef.current >= POLL_INTERVAL_MS) {
        runTick()
      }
    }

    syncPolling()
    document.addEventListener('visibilitychange', syncPolling)
    return () => {
      document.removeEventListener('visibilitychange', syncPolling)
      if (intervalId !== undefined) clearInterval(intervalId)
    }
  }, [])

  const profileFetchKeys = useMemo(() => {
    if (!viewerPubkey) return orderedPubkeys
    return orderedPubkeys.filter((pk) => !hexPubkeysEqual(pk, viewerPubkey))
  }, [orderedPubkeys, viewerPubkey])

  useEffect(() => {
    if (profileFetchKeys.length === 0) {
      setProfileKind0ByPubkey({})
      setProfilesLoading(false)
      return
    }
    let cancelled = false
    setProfilesLoading(true)
    ;(async () => {
      try {
        const events = await replaceableEventService.fetchReplaceableEventsFromProfileFetchRelays(
          profileFetchKeys,
          kinds.Metadata
        )
        if (cancelled) return
        const next: Record<string, Event> = {}
        profileFetchKeys.forEach((pk, i) => {
          const e = events[i]
          if (e) next[pk] = e
        })
        setProfileKind0ByPubkey(next)
      } catch (err) {
        logger.debug('[FavoriteRelaysActivity] profile batch failed', { err })
        if (!cancelled) setProfileKind0ByPubkey({})
      } finally {
        if (!cancelled) setProfilesLoading(false)
      }
    })()
    return () => {
      cancelled = true
    }
  }, [profileFetchKeys])

  const displayPubkeys = useMemo(() => {
    if (!viewerPubkey) return orderedPubkeys
    return orderedPubkeys.filter((pk) => !hexPubkeysEqual(pk, viewerPubkey))
  }, [orderedPubkeys, viewerPubkey])

  const effectiveFollowings = followings.length > 0 ? followings : fallbackFollowings
  const { followPubkeys, otherPubkeys, followCount, otherCount } = useMemo(
    () => partitionByFollows(displayPubkeys, effectiveFollowings),
    [displayPubkeys, effectiveFollowings]
  )

  const pubkeys = useMemo(
    () => [...followPubkeys, ...otherPubkeys],
    [followPubkeys, otherPubkeys]
  )

  const value: TFavoriteRelaysActivityContext = useMemo(
    () => ({
      followPubkeys,
      otherPubkeys,
      followCount,
      otherCount,
      pubkeys,
      totalCount: displayPubkeys.length,
      loading,
      relayActivityReady,
      lastFetchedAtMs,
      profileKind0ByPubkey,
      profilesLoading,
      activeNpubsDrawerOpen,
      setActiveNpubsDrawerOpen,
      refetch: fetchActive
    }),
    [
      followPubkeys,
      otherPubkeys,
      followCount,
      otherCount,
      pubkeys,
      displayPubkeys.length,
      loading,
      relayActivityReady,
      lastFetchedAtMs,
      profileKind0ByPubkey,
      profilesLoading,
      activeNpubsDrawerOpen,
      fetchActive
    ]
  )

  return <FavoriteRelaysActivityContext.Provider value={value}>{children}</FavoriteRelaysActivityContext.Provider>
}