import type { LanguagesConfig, RuntimeI18nConfig } from '../types.ts'
import { toText } from './string.ts'

export const AUTO_LOCALE = 'auto'
export const PREFERENCE_COOKIE = 'vanilla-press'

export interface LocaleRouteEntry {
  code: string
  route: string
}

export function normalizeLocaleRoute(value: unknown = ''): string {
  return toText(value).trim().replace(/^\/+/, '').replace(/\/+$/g, '')
}

export function localeCode(value: unknown = ''): string {
  return toText(value).trim().toLowerCase()
}

export function localeRouteEntries(
  languages: LanguagesConfig = {}
): LocaleRouteEntry[] {
  const entries: LocaleRouteEntry[] = []
  const seen = new Set<string>()
  const locales = Array.isArray(languages.locales) ? languages.locales : []

  for (const locale of locales) {
    const key = localeCode(locale?.code)
    const value = normalizeLocaleRoute(locale?.path)
    if (!key || !value || seen.has(key)) continue

    seen.add(key)
    entries.push({ code: toText(locale.code), route: value })
  }

  return entries
}

export function defaultLocaleRoute(
  i18n: RuntimeI18nConfig = {},
  languages: LanguagesConfig = {}
): string {
  const entries = localeRouteEntries(languages)
  if (!entries.length) return AUTO_LOCALE

  const preferred = localeCode(i18n.locale || languages.locale)
  return (
    entries.find((entry) => localeCode(entry.code) === preferred)?.route ||
    entries[0].route
  )
}

export function localeRouteForCode(
  code: unknown,
  i18n: RuntimeI18nConfig = {},
  languages: LanguagesConfig = {}
): string {
  const key = localeCode(code)
  return (
    localeRouteEntries(languages).find(
      (entry) => localeCode(entry.code) === key
    )?.route || ''
  )
}

export function localeRouteValues(
  i18n: RuntimeI18nConfig = {},
  languages: LanguagesConfig = {}
): string[] {
  return localeRouteEntries(languages).map((entry) => entry.route)
}

export function isLocaleRoute(
  value: unknown,
  i18n: RuntimeI18nConfig = {},
  languages: LanguagesConfig = {}
): boolean {
  const route = normalizeLocaleRoute(value)
  return !!route && localeRouteValues(i18n, languages).includes(route)
}

export function i18nRedirectBootScript(
  i18n: RuntimeI18nConfig = {},
  languages: LanguagesConfig = {}
): string {
  const defaultRoute = defaultLocaleRoute(i18n, languages)
  const routes = localeRouteValues(i18n, languages)

  return `(function(w,d,n){var a=${JSON.stringify(AUTO_LOCALE)},r=${JSON.stringify(routes)},f=${JSON.stringify(defaultRoute)},m=d.cookie.match(new RegExp('(?:^|; )'+n+'=([^;]*)')),p=null,o={};function c(){d.cookie=n+'='+encodeURIComponent(JSON.stringify(p))+'; expires='+new Date(Date.now()+31536e6).toUTCString()+'; path=/; SameSite=Lax'}if(m){try{p=JSON.parse(decodeURIComponent(m[1]))||{}}catch(e){p={}}}if(p===null){p=o;c()}var l=typeof p.locale==='string'?p.locale:'';if(!r.length){if(l!==a){p.locale=a;c()}return}if(!l){l=f;p.locale=l;c()}if(l===a)return;if(r.indexOf(l)<0){l=f;p.locale=l;c()}if(!l||l===a)return;var s=w.location.search+w.location.hash,t='./'+l+'/index.html';w.location.replace(t+s)})(window,document,${JSON.stringify(PREFERENCE_COOKIE)});`
}