feat: public API, SEO and existing surfaces

web/src/lib/localizedSeo.ts

@@ -0,0 +1,120 @@
+import { locale, t } from '@/i18n'
+import type { ResolvedSeo } from '@/lib/seoTypes'
+import { languageName } from '@/lib/siteLanguages'
+import { nameInSentence } from '@/lib/storyList'
+
+export interface LocalizedSeoContext {
+	lang: string
+	siteName: string
+	siteKey: string
+	pattern: string | null
+	defaultLang: string
+	disabledLangs: string[]
+	published: boolean
+	socialState: string
+	resolved: ResolvedSeo | null
+}
+
+export function pageLanguage(context: LocalizedSeoContext) {
+	return languageName(context.lang, locale.value)
+}
+
+export function breadcrumbOf(url: string) {
+	try {
+		const parsed = new URL(url)
+		const segments = parsed.pathname.split('/').filter(Boolean)
+		return [parsed.host, ...segments].join(' › ')
+	} catch {
+		return url
+	}
+}
+
+export function canonicalNote(context: LocalizedSeoContext) {
+	if (context.resolved?.fallbacks.canonical === 'canonical_url') {
+		return t('Set by hand as a canonical override on this version.')
+	}
+	return t(
+		'Built from the Public URL pattern {0}. Each language points to itself unless you set a canonical override.',
+		[context.pattern ?? ''],
+	)
+}
+
+export function disabledNote(context: LocalizedSeoContext) {
+	if (context.disabledLangs.length === 0) {
+		return t('Drafts are left out.')
+	}
+	const names = context.disabledLangs.map((tag) => nameInSentence(tag))
+	const list = names.join(', ')
+	return names.length === 1
+		? t('Drafts and the disabled {0} language are left out.', [list])
+		: t('Drafts and the disabled languages {0} are left out.', [list])
+}
+
+export function socialLocaleLine(context: LocalizedSeoContext) {
+	const value = context.resolved?.og.locale ?? ''
+	if (!value) {
+		return t('Social locale not set')
+	}
+	return context.socialState === 'derived' ? t('Derived: {0}', [value]) : t('Set: {0}', [value])
+}
+
+export function socialLocaleNote(context: LocalizedSeoContext) {
+	const name = pageLanguage(context)
+	if (!context.resolved?.og.locale) {
+		return t(
+			'{0} has no region in its code and no social locale is set for it, so og:locale and og:locale:alternate are left out. An owner can set one in {1} languages.',
+			[name, context.siteName],
+		)
+	}
+	if (context.socialState === 'derived') {
+		return t(
+			'Taken from the region of the language code or of the site locale. An owner can set another in {0} languages.',
+			[context.siteName],
+		)
+	}
+	return t(
+		'Set by an owner for {0} in {1} languages. A region is never guessed from the language.',
+		[name, context.siteName],
+	)
+}
+
+export function titleHelp(context: LocalizedSeoContext) {
+	const source = context.resolved?.fallbacks.title
+	return source === 'title' ? t('Fallback: {0} title', [nameInSentence(context.lang)]) : ''
+}
+
+export function descriptionHelp(context: LocalizedSeoContext) {
+	const fallbacks = context.resolved?.fallbacks
+	if (!fallbacks) {
+		return ''
+	}
+	const name = nameInSentence(context.lang)
+	switch (fallbacks.description) {
+		case 'excerpt':
+			return t('Fallback: {0} excerpt', [name])
+		case 'body':
+			return t('Fallback: {0} body', [name])
+		case 'site':
+			return t('Fallback: {0} site description', [name])
+		case 'none':
+			return fallbacks.site_text_skipped
+				? t('No fallback. Empty. {0} site default not used. The tag is left out.', [
+						nameInSentence(context.defaultLang),
+					])
+				: t('No fallback')
+		default:
+			return ''
+	}
+}
+
+export function descriptionBadge(context: LocalizedSeoContext) {
+	const fallbacks = context.resolved?.fallbacks
+	if (fallbacks?.description === 'site') {
+		return t('Uses site text')
+	}
+	return fallbacks?.site_text_skipped ? t('Tag left out') : ''
+}
+
+export function altHelp() {
+	return t('Written per language.')
+}