import type { Event } from 'nostr-tools'
import { extractTagsFromEvent } from '../nostrTagSystem'
import { generateSeriesHashId } from '../hashIdGenerator'
import type { ExtractedSeries } from './types'
import { getMetadataFromEvent } from './metadataJson'
import { firstString } from './utils'

export async function extractSeriesFromEvent(event: Event): Promise<ExtractedSeries | null> {
  const tags = extractTagsFromEvent(event)
  if (tags.type !== 'series') {
    return null
  }
  const metadata = getMetadataFromEvent(event)
  if (metadata?.type === 'series') {
    const seriesData = buildSeriesDataFromMetadata({ event, tags, metadata })
    const id = await generateSeriesHashId(seriesData)
    return buildExtractedSeries({ eventId: event.id, id, data: seriesData })
  }

  if (!tags.title || !tags.description) {
    return null
  }
  const base = {
    pubkey: event.pubkey,
    title: tags.title,
    description: tags.description,
    preview: (tags.preview as string) ?? event.content.substring(0, 200),
    category: tags.category ?? 'sciencefiction',
    ...(tags.coverUrl ? { coverUrl: tags.coverUrl } : {}),
  }
  const id = await generateSeriesHashId(base)
  return buildExtractedSeries({ eventId: event.id, id, data: base })
}

function buildSeriesDataFromMetadata(params: {
  event: Event
  tags: ReturnType<typeof extractTagsFromEvent>
  metadata: Record<string, unknown>
}): { pubkey: string; title: string; description: string; preview: string; coverUrl?: string; category: string } {
  const title = firstString(params.metadata.title, params.tags.title) ?? ''
  const preview = firstString(params.metadata.preview, params.tags.preview) ?? params.event.content.substring(0, 200)
  const pubkey = firstString(params.metadata.pubkey, params.event.pubkey) ?? params.event.pubkey
  const coverUrl = firstString(params.metadata.coverUrl, params.tags.coverUrl)
  const result: { pubkey: string; title: string; description: string; preview: string; coverUrl?: string; category: string } = {
    pubkey,
    title,
    description: firstString(params.metadata.description) ?? '',
    preview,
    category: firstString(params.metadata.category, params.tags.category, 'sciencefiction') ?? 'sciencefiction',
  }
  if (coverUrl) {
    result.coverUrl = coverUrl
  }
  return result
}

function buildExtractedSeries(params: {
  eventId: string
  id: string
  data: { pubkey: string; title: string; description: string; preview: string; coverUrl?: string; category: string }
}): ExtractedSeries {
  return {
    type: 'series',
    id: params.id,
    pubkey: params.data.pubkey,
    title: params.data.title,
    description: params.data.description,
    category: params.data.category,
    eventId: params.eventId,
    ...(params.data.coverUrl ? { coverUrl: params.data.coverUrl } : {}),
    ...(params.data.preview ? { preview: params.data.preview } : {}),
  }
}