elk/server/api/og-image.ts

import opengraph from 'opengraph-io'

// This API-Endpoint will be cached via nuxt.config.ts -> nitro.routeRules['/api/og-image'].cache.maxAge = 86400

let openGraphClient: any = null

function getOpenGraphClient(): any {
  if (openGraphClient == null)
    openGraphClient = opengraph({ appId: process.env.NUXT_OPENGRAPH_API, fullRender: true })

  return openGraphClient
}

function extractOgImageUrl(html: string): string {
  const match = html.match(/<meta property="og:image" content="([^"]+)" \/>/)
  return match?.[1] ?? ''
}

export default defineEventHandler(async (event) => {
  const { cardUrl } = getQuery(event)

  if (!cardUrl) {
    throw createError({
      statusCode: 422,
      statusMessage: 'Missing cardUrl.',
    })
  }

  if (typeof cardUrl !== 'string') {
    throw createError({
      statusCode: 422,
      statusMessage: 'cardUrl must be string.',
    })
  }

  let ogImageUrl = ''

  // First we want to try to get the og:image from the html
  // But sometimes it is not included due to async JS loading
  const html = await $fetch<string>(cardUrl)
  ogImageUrl = extractOgImageUrl(html)

  // If no og:image was found, try to get it from opengraph.io
  if (!ogImageUrl) {
    const response = await getOpenGraphClient().getSiteInfo(cardUrl)

    ogImageUrl = response?.openGraph?.image?.url ?? ''
  }

  // eslint-disable-next-line no-console
  console.log(JSON.stringify({ cardUrl, ogImageUrl }))

  await send(event, ogImageUrl)
})