story-research-zapwall/lib/contentDeliveryVerification.ts

import { nostrService } from './nostr'
import type { SimplePoolWithSub } from '@/types/nostr-tools-extended'
import { getPrimaryRelaySync } from './config'
import type { Event } from 'nostr-tools'

export interface ContentDeliveryStatus {
  messageEventId: string | null
  published: boolean
  verifiedOnRelay: boolean
  retrievable: boolean
  error?: string
}

/**
 * Verify that private content was successfully delivered to recipient
 * Checks multiple aspects to ensure delivery certainty
 */
function createContentDeliveryFilters(authorPubkey: string, recipientPubkey: string, articleId: string, messageEventId: string) {
  const filters: Array<{
    kinds: number[]
    ids?: string[]
    authors: string[]
    '#p': string[]
    '#e': string[]
    limit: number
  }> = [
    {
      kinds: [4],
      authors: [authorPubkey],
      '#p': [recipientPubkey],
      '#e': [articleId],
      limit: 1,
    },
  ]

  if (messageEventId && filters[0]) {
    filters[0].ids = [messageEventId]
  }
  return filters
}

function setupContentDeliveryHandlers(
  sub: SimplePoolWithSub['sub'] extends (...args: any[]) => infer R ? R : never,
  status: ContentDeliveryStatus,
  finalize: (result: ContentDeliveryStatus) => void,
  isResolved: () => boolean
): void {
  sub.on('event', (event: Event) => {
    status.published = true
    status.verifiedOnRelay = true
    status.messageEventId = event.id
    status.retrievable = true
    finalize(status)
  })

  sub.on('eose', () => {
    if (!status.published) {
      status.error = 'Message not found on relay'
    }
    finalize(status)
  })

  setTimeout(() => {
    if (!isResolved()) {
      if (!status.published) {
        status.error = 'Timeout waiting for message verification'
      }
      finalize(status)
    }
  }, 5000)
}

function createContentDeliverySubscription(
  pool: SimplePoolWithSub,
  authorPubkey: string,
  recipientPubkey: string,
  articleId: string,
  messageEventId: string
) {
  const filters = createContentDeliveryFilters(authorPubkey, recipientPubkey, articleId, messageEventId)
  const relayUrl = getPrimaryRelaySync()
  return pool.sub([relayUrl], filters)
}

function createContentDeliveryPromise(
  sub: SimplePoolWithSub['sub'] extends (...args: any[]) => infer R ? R : never,
  status: ContentDeliveryStatus
): Promise<ContentDeliveryStatus> {
  return new Promise((resolve) => {
    let resolved = false

    const finalize = (result: ContentDeliveryStatus) => {
      if (resolved) {
        return
      }
      resolved = true
      sub.unsub()
      resolve(result)
    }

    setupContentDeliveryHandlers(sub, status, finalize, () => resolved)
  })
}

export function verifyContentDelivery(
  articleId: string,
  authorPubkey: string,
  recipientPubkey: string,
  messageEventId: string
): Promise<ContentDeliveryStatus> {
  const status: ContentDeliveryStatus = {
    messageEventId,
    published: false,
    verifiedOnRelay: false,
    retrievable: false,
  }

  try {
    const pool = nostrService.getPool()
    if (!pool) {
      status.error = 'Pool not initialized'
      return Promise.resolve(status)
    }

    const poolWithSub = pool as SimplePoolWithSub
    const sub = createContentDeliverySubscription(poolWithSub, authorPubkey, recipientPubkey, articleId, messageEventId)
    return createContentDeliveryPromise(sub, status)
  } catch (error) {
    status.error = error instanceof Error ? error.message : 'Unknown error'
    return Promise.resolve(status)
  }
}

/**
 * Check if recipient can retrieve the private message
 * This verifies that the message is accessible with the recipient's key
 */
export async function verifyRecipientCanRetrieve(
  articleId: string,
  authorPubkey: string,
  recipientPubkey: string,
  messageEventId: string
): Promise<boolean> {
  try {
    const status = await verifyContentDelivery(articleId, authorPubkey, recipientPubkey, messageEventId)
    return status.retrievable && status.verifiedOnRelay
  } catch (error) {
    console.error('Error verifying recipient can retrieve', {
      articleId,
      recipientPubkey,
      messageEventId,
      error: error instanceof Error ? error.message : 'Unknown error',
    })
    return false
  }
}