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.')
}