import { createHash } from 'node:crypto'
import { eq } from 'drizzle-orm'
import { linkPreviews } from '../db/schema'

const CACHE_TTL_MS = 1000 * 60 * 60 * 24

export default defineEventHandler(async (event) => {
  const url = String(getQuery(event).url ?? '')
  if (!/^https?:\/\//i.test(url) || url.length > 2048) {
    throw createError({ statusCode: 400, statusMessage: 'Ungültige URL' })
  }

  const urlHash = createHash('sha256').update(url).digest('hex')
  const db = useDb()
  const [cached] = await db
    .select()
    .from(linkPreviews)
    .where(eq(linkPreviews.urlHash, urlHash))
    .limit(1)

  if (cached && Date.now() - cached.fetchedAt.getTime() < CACHE_TTL_MS) {
    return { image: cached.image, title: cached.title }
  }

  const preview = await fetchLinkPreview(url)
  // Vorschaubild lokal speichern — die Remote-URL ist nicht stabil
  const image = preview.image
    ? (await savePreviewImage(`links/${urlHash}`, preview.image)) ?? preview.image
    : null
  await db
    .insert(linkPreviews)
    .values({ urlHash, url, image, title: preview.title, fetchedAt: new Date() })
    .onDuplicateKeyUpdate({
      set: { image, title: preview.title, fetchedAt: new Date() },
    })
  return { image, title: preview.title }
})