// The single source of truth for this app's locales + the URL-prefix
// helpers. `app.config.ts` lists the same codes for the build pipeline;
// the [locale] mirror pages + the layout's <I18nProvider> read THIS file.
//
// Keep SUPPORTED_LOCALES / DEFAULT_LOCALE in sync with `locales` /
// `defaultLocale` in app.config.ts.

import { useLocation } from '@voltro/web'
import en from '../locales/en'
import de from '../locales/de'

export const SUPPORTED_LOCALES = ['en', 'de'] as const
export const DEFAULT_LOCALE = 'en'

export type Locale = (typeof SUPPORTED_LOCALES)[number]

// The catalogs, keyed by code. The layout picks one to feed the inner
// <I18nProvider>; `meta` (build-time, per locale) reads one via getCatalog.
export const CATALOGS = { en, de } as const

// Every catalog mirrors `en`'s keys (defineLocale enforces it), so a
// plain string-record over en's keys is the common type both satisfy —
// what `meta` reads at build time (`c['meta.home.title']` → string).
export type Messages = Record<keyof typeof en, string>

const isSupported = (v: string): v is Locale =>
  (SUPPORTED_LOCALES as ReadonlyArray<string>).includes(v)

export const getCatalog = (locale: string): Messages =>
  isSupported(locale) ? CATALOGS[locale] : CATALOGS[DEFAULT_LOCALE]

// `/de/about` → 'de'; `/about` → 'en' (default lives at the bare path).
export const localeFromPathname = (pathname: string): Locale => {
  const match = /^\/([a-z]{2})(?:\/|$)/.exec(pathname)
  return match && isSupported(match[1]!) ? (match[1] as Locale) : DEFAULT_LOCALE
}

// Reactive: useLocation re-renders on client-side nav, so the layout's
// provider swaps catalogs when you move between /about and /de/about
// without a full reload.
export const useUrlLocale = (): Locale => localeFromPathname(useLocation())

// '/about' + 'de' → '/de/about'; the default locale stays bare ('/about').
export const withLocalePrefix = (path: string, locale: string): string => {
  if (locale === DEFAULT_LOCALE) return path
  const p = path.startsWith('/') ? path : `/${path}`
  return p === '/' ? `/${locale}` : `/${locale}${p}`
}

// '/de/about' → '/about'; '/about' → '/about'. The inverse of the above,
// used to keep the active path when switching language.
export const stripLocalePrefix = (pathname: string): string => {
  const match = /^\/([a-z]{2})(\/.*|$)/.exec(pathname)
  return match && isSupported(match[1]!) ? match[2] || '/' : pathname
}