import { RelayPool } from 'applesauce-relay'
import { lastValueFrom, take } from 'rxjs'
import { nip19 } from 'nostr-tools'
import { AddressPointer } from 'nostr-tools/nip19'
import { Helpers } from 'applesauce-core'
import { RELAYS } from '../config/relays'
import { prioritizeLocalRelays, partitionRelays, createParallelReqStreams } from '../utils/helpers'
import { merge, toArray as rxToArray } from 'rxjs'

const { getArticleTitle } = Helpers

/**
 * Fetch article title for a single naddr
 * Returns the title or null if not found/error
 */
export async function fetchArticleTitle(
  relayPool: RelayPool,
  naddr: string
): Promise<string | null> {
  try {
    const decoded = nip19.decode(naddr)
    
    if (decoded.type !== 'naddr') {
      return null
    }

    const pointer = decoded.data as AddressPointer

    // Define relays to query
    const baseRelays = pointer.relays && pointer.relays.length > 0 
      ? pointer.relays 
      : RELAYS
    const orderedRelays = prioritizeLocalRelays(baseRelays)
    const { local: localRelays, remote: remoteRelays } = partitionRelays(orderedRelays)

    // Fetch the article event
    const filter = {
      kinds: [pointer.kind],
      authors: [pointer.pubkey],
      '#d': [pointer.identifier]
    }

    // Parallel local+remote: collect up to one event from each
    const { local$, remote$ } = createParallelReqStreams(relayPool, localRelays, remoteRelays, filter, 1200, 5000)
    const events = await lastValueFrom(
      merge(local$.pipe(take(1)), remote$.pipe(take(1))).pipe(rxToArray())
    ) as unknown as { created_at: number }[]

    if (events.length === 0) {
      return null
    }

    // Sort by created_at and take the most recent
    events.sort((a, b) => b.created_at - a.created_at)
    const article = events[0] as unknown as Parameters<typeof getArticleTitle>[0]

    return getArticleTitle(article) || null
  } catch (err) {
    console.warn('Failed to fetch article title for', naddr, err)
    return null
  }
}

/**
 * Fetch titles for multiple naddrs in parallel
 * Returns a map of naddr -> title
 */
export async function fetchArticleTitles(
  relayPool: RelayPool,
  naddrs: string[]
): Promise<Map<string, string>> {
  const titleMap = new Map<string, string>()
  
  // Fetch all titles in parallel
  const results = await Promise.allSettled(
    naddrs.map(async (naddr) => {
      const title = await fetchArticleTitle(relayPool, naddr)
      return { naddr, title }
    })
  )

  // Process results
  results.forEach((result) => {
    if (result.status === 'fulfilled' && result.value.title) {
      titleMap.set(result.value.naddr, result.value.title)
    }
  })

  return titleMap
}