// The layer's labels (UI-SPEC L8) in the page's content locale: the resolve
// answer's locale, then html_lang's primary subtag, then en. An app
// overrides or adds locales in its app.config.ts:
//
//   export default defineAppConfig({ seo: { labels: { pl: { sitemap: { title: 'Spis stron' } } } } })
//
// Component props override both.

import type { ComputedRef, MaybeRefOrGetter } from 'vue'
import { pickLabels, type SeoLabelOverrides, type SeoLabels } from '../utils/labels.ts'

/**
 * The labels of the page's content locale, or of `locale` when given and
 * not empty (the HTML sitemap pages know theirs from the route).
 */
export function useSeoLabels(locale?: MaybeRefOrGetter<string | undefined | null>): ComputedRef<SeoLabels> {
  const answer = useSeoAnswer()
  const appConfig = useAppConfig() as { seo?: { labels?: SeoLabelOverrides } }
  return computed(() => {
    const own = toValue(locale)
    if (own) return pickLabels(own, '', appConfig.seo?.labels ?? {})
    return pickLabels(answer.value?.locale, answer.value?.html_lang, appConfig.seo?.labels ?? {})
  })
}