module.exports.formatSlug = reference => {
  let slug = ''

  const { relationTo, value } = reference

  if (typeof value === 'object' && value !== null) {
    const { slug: referenceSlug, breadcrumbs } = value

    // pages could be nested, so use breadcrumbs
    if (relationTo === 'pages') {
      if (breadcrumbs) {
        const { url: lastCrumbURL = '' } = breadcrumbs?.[breadcrumbs.length - 1] || {} // last crumb
        slug = lastCrumbURL
      } else {
        slug = referenceSlug
      }
    }

    if (relationTo !== 'pages') {
      slug = `/${relationTo}/${referenceSlug}`

      if (relationTo === 'media') {
        slug = value.url
      }
    }
  }

  return slug
}