boris/src/services/highlights/fetchForArticle.ts

import { RelayPool, completeOnEose, onlyEvents } from 'applesauce-relay'
import { lastValueFrom, merge, Observable, takeUntil, timer, tap, toArray } from 'rxjs'
import { NostrEvent } from 'nostr-tools'
import { Highlight } from '../../types/highlights'
import { RELAYS } from '../../config/relays'
import { prioritizeLocalRelays, partitionRelays } from '../../utils/helpers'
import { eventToHighlight, dedupeHighlights, sortHighlights } from '../highlightEventProcessor'
import { UserSettings } from '../settingsService'
import { rebroadcastEvents } from '../rebroadcastService'

export const fetchHighlightsForArticle = async (
  relayPool: RelayPool,
  articleCoordinate: string,
  eventId?: string,
  onHighlight?: (highlight: Highlight) => void,
  settings?: UserSettings
): Promise<Highlight[]> => {
  try {
    const seenIds = new Set<string>()
    const processEvent = (event: NostrEvent): Highlight | null => {
      if (seenIds.has(event.id)) return null
      seenIds.add(event.id)
      return eventToHighlight(event)
    }

    const orderedRelays = prioritizeLocalRelays(RELAYS)
    const { local: localRelays, remote: remoteRelays } = partitionRelays(orderedRelays)

    const aLocal$ = localRelays.length > 0
      ? relayPool
          .req(localRelays, { kinds: [9802], '#a': [articleCoordinate] })
          .pipe(
            onlyEvents(),
            tap((event: NostrEvent) => {
              const highlight = processEvent(event)
              if (highlight && onHighlight) onHighlight(highlight)
            }),
            completeOnEose(),
            takeUntil(timer(1200))
          )
      : new Observable<NostrEvent>((sub) => sub.complete())
    const aRemote$ = remoteRelays.length > 0
      ? relayPool
          .req(remoteRelays, { kinds: [9802], '#a': [articleCoordinate] })
          .pipe(
            onlyEvents(),
            tap((event: NostrEvent) => {
              const highlight = processEvent(event)
              if (highlight && onHighlight) onHighlight(highlight)
            }),
            completeOnEose(),
            takeUntil(timer(6000))
          )
      : new Observable<NostrEvent>((sub) => sub.complete())
    const aTagEvents: NostrEvent[] = await lastValueFrom(merge(aLocal$, aRemote$).pipe(toArray()))

    let eTagEvents: NostrEvent[] = []
    if (eventId) {
      const eLocal$ = localRelays.length > 0
        ? relayPool
            .req(localRelays, { kinds: [9802], '#e': [eventId] })
            .pipe(
              onlyEvents(),
              tap((event: NostrEvent) => {
                const highlight = processEvent(event)
                if (highlight && onHighlight) onHighlight(highlight)
              }),
              completeOnEose(),
              takeUntil(timer(1200))
            )
        : new Observable<NostrEvent>((sub) => sub.complete())
      const eRemote$ = remoteRelays.length > 0
        ? relayPool
            .req(remoteRelays, { kinds: [9802], '#e': [eventId] })
            .pipe(
              onlyEvents(),
              tap((event: NostrEvent) => {
                const highlight = processEvent(event)
                if (highlight && onHighlight) onHighlight(highlight)
              }),
              completeOnEose(),
              takeUntil(timer(6000))
            )
        : new Observable<NostrEvent>((sub) => sub.complete())
      eTagEvents = await lastValueFrom(merge(eLocal$, eRemote$).pipe(toArray()))
    }

    const rawEvents = [...aTagEvents, ...eTagEvents]
    await rebroadcastEvents(rawEvents, relayPool, settings)
    const uniqueEvents = dedupeHighlights(rawEvents)
    const highlights: Highlight[] = uniqueEvents.map(eventToHighlight)
    return sortHighlights(highlights)
  } catch {
    return []
  }
}