story-research-zapwall/lib/helpers/eventCacheHelper.ts

/**
 * Helper for grouping and caching events by hash
 * Centralizes the pattern of grouping events by hash ID and caching the latest version
 */

import type { Event } from 'nostr-tools'
import { extractTagsFromEvent } from '../nostrTagSystem'
import { parseObjectId } from '../urlGenerator'
import { getLatestVersion } from '../versionManager'
import type { ObjectType } from '../objectCache'
import { writeObjectToCache } from './writeObjectHelper'

export interface EventCacheConfig {
  objectType: ObjectType
  extractor: (event: Event) => Promise<unknown>
  getHash?: (extracted: unknown) => string | null
  getIndex?: (extracted: unknown) => number
  getVersion?: (event: Event) => number
  getHidden?: (event: Event) => boolean
}


interface ExtractedObjectWithId {
  id?: string
  index?: number
}

function groupEventsByHashId(events: Event[]): Map<string, Event[]> {
  const eventsByHashId = new Map<string, Event[]>()

  for (const event of events) {
    const tags = extractTagsFromEvent(event)
    const { id } = tags
    if (id) {
      const parsed = parseObjectId(id)
      const hash = parsed.hash ?? id

      const current = eventsByHashId.get(hash)
      if (current) {
        current.push(event)
      } else {
        eventsByHashId.set(hash, [event])
      }
    }
  }

  return eventsByHashId
}

function resolveExtractedId(extracted: unknown, getHash: EventCacheConfig['getHash']): string | undefined {
  const extractedHash = getHash ? getHash(extracted) : null
  const extractedObj = extracted as ExtractedObjectWithId
  return extractedHash ?? extractedObj.id
}

function resolveHashAndIndex(
  extractedId: string,
  extracted: unknown,
  getIndex: EventCacheConfig['getIndex']
): { hash: string; index: number } {
  const parsed = parseObjectId(extractedId)
  const extractedObj = extracted as ExtractedObjectWithId
  const hash = parsed.hash ?? extractedId
  const index = getIndex ? getIndex(extracted) : (parsed.index ?? extractedObj.index ?? 0)
  return { hash, index }
}

function resolveVersionAndHidden(
  latestEvent: Event,
  getVersion: EventCacheConfig['getVersion'],
  getHidden: EventCacheConfig['getHidden']
): { version: number; hidden: boolean } {
  const tags = extractTagsFromEvent(latestEvent)
  const version = getVersion ? getVersion(latestEvent) : (tags.version ?? 0)
  const hidden = getHidden ? getHidden(latestEvent) : (tags.hidden ?? false)
  return { version, hidden }
}

async function cacheLatestEventForHashGroup(hashEvents: Event[], config: EventCacheConfig): Promise<void> {
  const { objectType, extractor, getHash, getIndex, getVersion, getHidden } = config

  const latestEvent = getLatestVersion(hashEvents)
  if (!latestEvent) {
    return
  }

  const extracted = await extractor(latestEvent)
  if (!extracted) {
    return
  }

  const extractedId = resolveExtractedId(extracted, getHash)
  if (!extractedId) {
    return
  }

  const { hash, index } = resolveHashAndIndex(extractedId, extracted, getIndex)
  const { version, hidden } = resolveVersionAndHidden(latestEvent, getVersion, getHidden)

  await writeObjectToCache({
    objectType,
    hash,
    event: latestEvent,
    parsed: extracted,
    version,
    hidden,
    index,
  })
}

/**
 * Group events by hash ID and cache the latest version of each
 */
export async function groupAndCacheEventsByHash(
  events: Event[],
  config: EventCacheConfig
): Promise<void> {
  const eventsByHashId = groupEventsByHashId(events)
  for (const hashEvents of eventsByHashId.values()) {
    await cacheLatestEventForHashGroup(hashEvents, config)
  }
}

/**
 * Cache a single event as an object
 * Simplified version for direct event caching
 */
export async function cacheEventAsObject(
  event: Event,
  objectType: ObjectType,
  extractor: (event: Event) => Promise<unknown>
): Promise<boolean> {
  const extracted = await extractor(event)
  if (!extracted) {
    return false
  }

  const tags = extractTagsFromEvent(event)
  const hash = (extracted as { hash?: string })?.hash ?? (extracted as { id?: string })?.id ?? ''
  if (!hash) {
    return false
  }

  const index = (extracted as { index?: number })?.index ?? 0

  await writeObjectToCache({
    objectType,
    hash,
    event,
    parsed: extracted,
    version: tags.version,
    hidden: tags.hidden,
    index,
  })

  return true
}