import type { Event } from 'nostr-tools'
import { extractTagsFromEvent } from '../nostrTagSystem'
import { generatePublicationHashId } from '../hashIdGenerator'
import type { ExtractedPublication } from './types'
import { getMetadataFromEvent } from './metadataJson'
import { firstNumber, firstString } from './utils'

type PublicationPages = Array<{ number: number; type: 'markdown' | 'image'; content: string }>

export async function extractPublicationFromEvent(event: Event): Promise<ExtractedPublication | null> {
  const tags = extractTagsFromEvent(event)
  if (tags.type !== 'publication') {
    return null
  }
  const metadata = getMetadataFromEvent(event)
  if (metadata?.type === 'publication') {
    const publicationData = buildPublicationDataFromMetadata({ event, tags, metadata })
    const id = await generatePublicationHashId(publicationData)
    const pages = readPublicationPages(metadata)
    return buildExtractedPublication({ eventId: event.id, id, data: publicationData, pages })
  }
  if (!tags.title) {
    return null
  }
  const publicationData = {
    pubkey: event.pubkey,
    title: tags.title,
    preview: (tags.preview as string) ?? event.content.substring(0, 200),
    category: tags.category ?? 'sciencefiction',
    zapAmount: tags.zapAmount ?? 800,
    ...(tags.seriesId ? { seriesId: tags.seriesId } : {}),
    ...(tags.bannerUrl ? { bannerUrl: tags.bannerUrl } : {}),
  }
  const id = await generatePublicationHashId(publicationData)
  return buildExtractedPublication({ eventId: event.id, id, data: publicationData, pages: undefined })
}

function buildPublicationDataFromMetadata(params: {
  event: Event
  tags: ReturnType<typeof extractTagsFromEvent>
  metadata: Record<string, unknown>
}): {
  pubkey: string
  title: string
  preview: string
  category: string
  seriesId?: string
  bannerUrl?: string
  zapAmount: number
} {
  const base: {
    pubkey: string
    title: string
    preview: string
    category: string
    seriesId?: string
    bannerUrl?: string
    zapAmount: number
  } = {
    pubkey: firstString(params.metadata.pubkey, params.event.pubkey) ?? params.event.pubkey,
    title: firstString(params.metadata.title, params.tags.title) ?? '',
    preview: firstString(params.metadata.preview, params.tags.preview) ?? params.event.content.substring(0, 200),
    category: firstString(params.metadata.category, params.tags.category, 'sciencefiction') ?? 'sciencefiction',
    zapAmount: firstNumber(params.metadata.zapAmount, params.tags.zapAmount) ?? 800,
  }
  const seriesId = firstString(params.metadata.seriesId, params.tags.seriesId)
  if (seriesId) {
    base.seriesId = seriesId
  }
  const bannerUrl = firstString(params.metadata.bannerUrl, params.tags.bannerUrl)
  if (bannerUrl) {
    base.bannerUrl = bannerUrl
  }
  return base
}

function readPublicationPages(metadata: Record<string, unknown>): PublicationPages | undefined {
  const pages = metadata.pages as PublicationPages | undefined
  return pages && Array.isArray(pages) && pages.length > 0 ? pages : undefined
}

function buildExtractedPublication(params: {
  eventId: string
  id: string
  data: {
    pubkey: string
    title: string
    preview: string
    category: string
    seriesId?: string
    bannerUrl?: string
    zapAmount: number
  }
  pages: PublicationPages | undefined
}): ExtractedPublication {
  return {
    type: 'publication',
    id: params.id,
    pubkey: params.data.pubkey,
    title: params.data.title,
    preview: params.data.preview,
    category: params.data.category,
    zapAmount: params.data.zapAmount,
    eventId: params.eventId,
    ...(params.data.seriesId ? { seriesId: params.data.seriesId } : {}),
    ...(params.data.bannerUrl ? { bannerUrl: params.data.bannerUrl } : {}),
    ...(params.pages ? { pages: params.pages } : {}),
  }
}