Bpistle/src/providers/FeedProvider.tsx

import { IS_COMMUNITY_MODE, COMMUNITY_RELAY_SETS, COMMUNITY_RELAYS } from '@/constants'
import { getRelaySetFromEvent } from '@/lib/event-metadata'
import { isWebsocketUrl, normalizeUrl } from '@/lib/url'
import indexedDb from '@/services/indexed-db.service'
import storage from '@/services/local-storage.service'
import { TFeedInfo, TFeedType, TRelaySet } from '@/types'
import { kinds } from 'nostr-tools'
import { createContext, useContext, useEffect, useRef, useState } from 'react'
import { useFavoriteRelays } from './FavoriteRelaysProvider'
import { useNostr } from './NostrProvider'

type TFeedContext = {
  feedInfo: TFeedInfo
  relayUrls: string[]
  isReady: boolean
  switchFeed: (
    feedType: TFeedType | null,
    options?: { activeRelaySetId?: string; pubkey?: string; relay?: string | null }
  ) => Promise<void>
}

const FeedContext = createContext<TFeedContext | undefined>(undefined)

export const useFeed = () => {
  const context = useContext(FeedContext)
  if (!context) {
    throw new Error('useFeed must be used within a FeedProvider')
  }
  return context
}

export function FeedProvider({ children }: { children: React.ReactNode }) {
  const { pubkey, isInitialized } = useNostr()
  const { relaySets } = useFavoriteRelays()
  const [relayUrls, setRelayUrls] = useState<string[]>([])
  const [isReady, setIsReady] = useState(false)
  const [feedInfo, setFeedInfo] = useState<TFeedInfo>(null)
  const feedInfoRef = useRef<TFeedInfo>(feedInfo)

  useEffect(() => {
    const init = async () => {
      if (!isInitialized) {
        return
      }

      let feedInfo: TFeedInfo = null
      if (pubkey) {
        const storedFeedInfo = storage.getFeedInfo(pubkey)
        if (storedFeedInfo) {
          feedInfo = storedFeedInfo
        } else {
          if (!IS_COMMUNITY_MODE) {
            feedInfo = { feedType: 'following' }
          }
        }
      }
      if (!feedInfo && IS_COMMUNITY_MODE) {
        feedInfo =
          COMMUNITY_RELAY_SETS.length > 0
            ? {
                feedType: 'relays',
                id: COMMUNITY_RELAY_SETS[0].id,
                name: COMMUNITY_RELAY_SETS[0].name
              }
            : { feedType: 'relay', id: COMMUNITY_RELAYS[0] }
      }

      if (feedInfo?.feedType === 'relays') {
        return await switchFeed('relays', { activeRelaySetId: feedInfo.id })
      }

      if (feedInfo?.feedType === 'relay') {
        return await switchFeed('relay', { relay: feedInfo.id })
      }

      // update following feed if pubkey changes
      if (feedInfo?.feedType === 'following' && pubkey) {
        return await switchFeed('following', { pubkey })
      }

      // update pinned feed if pubkey changes
      if (feedInfo?.feedType === 'pinned' && pubkey) {
        return await switchFeed('pinned', { pubkey })
      }

      setIsReady(true)
    }

    init()
  }, [pubkey, isInitialized])

  const switchFeed = async (
    feedType: TFeedType | null,
    options: {
      activeRelaySetId?: string | null
      pubkey?: string | null
      relay?: string | null
    } = {}
  ) => {
    if (!feedType) {
      setFeedInfo(null)
      feedInfoRef.current = null
      setRelayUrls([])
      return
    }

    setIsReady(false)
    if (feedType === 'relay') {
      const normalizedUrl = normalizeUrl(options.relay ?? '')
      if (!normalizedUrl || !isWebsocketUrl(normalizedUrl)) {
        setIsReady(true)
        return
      }

      const newFeedInfo = { feedType, id: normalizedUrl }
      setFeedInfo(newFeedInfo)
      feedInfoRef.current = newFeedInfo
      setRelayUrls([normalizedUrl])
      storage.setFeedInfo(newFeedInfo, pubkey)
      setIsReady(true)
      return
    }
    if (feedType === 'relays') {
      const relaySetId = options.activeRelaySetId ?? (relaySets.length > 0 ? relaySets[0].id : null)
      let relaySet: TRelaySet | null = null
      if (IS_COMMUNITY_MODE) {
        relaySet =
          COMMUNITY_RELAY_SETS.find((set) => set.id === relaySetId) ??
          (COMMUNITY_RELAY_SETS.length > 0 ? COMMUNITY_RELAY_SETS[0] : null)
      } else {
        if (!relaySetId || !pubkey) {
          setIsReady(true)
          return
        }

        relaySet =
          relaySets.find((set) => set.id === relaySetId) ??
          (relaySets.length > 0 ? relaySets[0] : null)

        if (!relaySet) {
          const storedRelaySetEvent = await indexedDb.getReplaceableEvent(
            pubkey,
            kinds.Relaysets,
            relaySetId
          )
          if (storedRelaySetEvent) {
            relaySet = getRelaySetFromEvent(storedRelaySetEvent)
          }
        }
      }

      if (relaySet) {
        const newFeedInfo = { feedType, id: relaySet.id }
        setFeedInfo(newFeedInfo)
        feedInfoRef.current = newFeedInfo
        setRelayUrls(relaySet.relayUrls)
        storage.setFeedInfo(newFeedInfo, pubkey)
        setIsReady(true)
      }
      setIsReady(true)
      return
    }
    if (feedType === 'following') {
      if (!options.pubkey) {
        setIsReady(true)
        return
      }
      const newFeedInfo = { feedType }
      setFeedInfo(newFeedInfo)
      feedInfoRef.current = newFeedInfo
      storage.setFeedInfo(newFeedInfo, pubkey)

      setRelayUrls([])
      setIsReady(true)
      return
    }
    if (feedType === 'pinned') {
      if (!options.pubkey) {
        setIsReady(true)
        return
      }
      const newFeedInfo = { feedType }
      setFeedInfo(newFeedInfo)
      feedInfoRef.current = newFeedInfo
      storage.setFeedInfo(newFeedInfo, pubkey)

      setRelayUrls([])
      setIsReady(true)
      return
    }
    setIsReady(true)
  }

  return (
    <FeedContext.Provider
      value={{
        feedInfo,
        relayUrls,
        isReady,
        switchFeed
      }}
    >
      {children}
    </FeedContext.Provider>
  )
}