export async function loadLocale(locale, supportedLocales) {
  const localeData = supportedLocales[locale]
  return typeof localeData === 'function' ? (await localeData()).default : localeData
}

export function useI18n(storage, initialLocale, emitter, supportedLocales) {
  const { getStore, setStore } = storage
  let translations = {}
  let locale = getStore('locale', initialLocale)

  const changeLocale = (newLocale, defaultLocale = initialLocale) => {
    loadLocale(newLocale, supportedLocales).then((i18n) => {
      translations.value = i18n
      setStore('locale', newLocale)
      locale.value = newLocale
      setStore('translations', i18n)
      if (Object.values(supportedLocales).length > 1) {
        emitter.emit('vf-toast-push', { label: 'The language is set to ' + newLocale })
        emitter.emit('vf-language-saved')
      }
    }).catch(e => {
      if (defaultLocale) {
        emitter.emit('vf-toast-push', { label: 'The selected locale is not yet supported!', type: 'error' })
        changeLocale(defaultLocale, null)
      } else {
        emitter.emit('vf-toast-push', { label: 'Locale cannot be loaded!', type: 'error' })
      }
    })
  }

  if (!getStore('locale') && !supportedLocales.length) {
    changeLocale(initialLocale)
  } else {
    translations.value = getStore('translations')
  }
  const sprintf = (str, ...argv) => !argv.length ? str : sprintf(str = str.replace('%s', argv.shift()), ...argv)

  function t(key, ...params) {
    if (translations.value && translations.value.hasOwnProperty(key)) {
      return sprintf(translations.value[key], ...params)
    }
    return sprintf(key, ...params)
  }

  return { t, changeLocale, locale }
}