import { nextTick } from 'vue'
import { createI18n } from 'vue-i18n'

import en from '@/locales/en.json'
import fr from '@/locales/fr.json'
import es from '@/locales/es.json'
import de from '@/locales/de.json'
import it from '@/locales/it.json'

export const APP_LOCALES = [
  { code: 'en', name: 'English' },
  { code: 'fr', name: 'Français' },
  { code: 'es', name: 'Español' },
  { code: 'de', name: 'Deutsch' },
  { code: 'it', name: 'Italiano' }
]

export function setupI18n(options = { locale: 'en' }) {
  const i18n = createI18n(options)
  setI18nLanguage(i18n, options.locale)
  return i18n
}

export function getI18nLanguage(i18n) {
  return i18n.mode === 'legacy' ? i18n.global.locale : i18n.global.locale.value
}

export function setI18nLanguage(i18n, locale) {
  if (i18n.mode === 'legacy') {
    i18n.global.locale = locale
  } else {
    i18n.global.locale.value = locale
  }
  /**
   * NOTE:
   * If you need to specify the language setting for headers, such as the `useAuthenticatedfetch`, set it here.
   */
  document.querySelector('html').setAttribute('lang', locale)
  localStorage.setItem('skape-carousel-locale', locale)
}

export async function loadLocaleMessages(i18n, locale) {
  // load locale messages with dynamic import
  const messages = await import(`./locales/${locale}.json`)

  // set locale and locale message
  i18n.global.setLocaleMessage(locale, messages.default)

  return await nextTick()
}

/**
 * Normalize a locale string to its base language code (e.g., 'en-US' -> 'en').
 * Handles invalid or unexpected input gracefully.
 *
 * @param {string} locale - The locale string to normalize.
 * @returns {string} - The normalized base language code (e.g., 'en'), or a default ('en') if input is invalid.
 */
export function normalizeLocale(locale) {
  if (typeof locale !== 'string' || locale.trim() === '') {
    console.warn('Invalid locale provided, defaulting to "en".')
    return 'en' // Default fallback
  }

  const parts = locale.split('-')
  const baseLocale = parts[0]?.trim().toLowerCase()

  if (!baseLocale || baseLocale.length < 2 || baseLocale.length > 3) {
    console.warn(`Unexpected locale format: "${locale}", defaulting to "en".`)
    return 'en' // Default fallback
  }

  return baseLocale
}

export const i18n = setupI18n({
  // locale: new URLSearchParams(window.location.search).get('locale') || 'en',
  locale: localStorage.getItem('skape-carousel-locale') || 'en',
  messages: {
    en,
    fr,
    es,
    de,
    it
  },
  fallbackLocale: 'en',
  legacy: false
})

// Export raw translations for AppProvider
export const messageFr = fr
export const messageEn = en
export const messageEs = es
export const messageDe = de
export const messageIt = it