audiobookshelf/client/plugins/i18n.js

import Vue from "vue"
import enUsStrings from '../strings/en-us.json'
import { supplant } from './utils'

const defaultCode = 'en-us'

const languageCodeMap = {
  'cs': { label: 'Čeština', dateFnsLocale: 'cs' },
  'da': { label: 'Dansk', dateFnsLocale: 'da' },
  'de': { label: 'Deutsch', dateFnsLocale: 'de' },
  'en-us': { label: 'English', dateFnsLocale: 'enUS' },
  'es': { label: 'Español', dateFnsLocale: 'es' },
  'fr': { label: 'Français', dateFnsLocale: 'fr' },
  'hr': { label: 'Hrvatski', dateFnsLocale: 'hr' },
  'it': { label: 'Italiano', dateFnsLocale: 'it' },
  'lt': { label: 'Lietuvių', dateFnsLocale: 'lt' },
  'nl': { label: 'Nederlands', dateFnsLocale: 'nl' },
  'no': { label: 'Norsk', dateFnsLocale: 'no' },
  'pl': { label: 'Polski', dateFnsLocale: 'pl' },
  'ru': { label: 'Русский', dateFnsLocale: 'ru' },
  'sv': { label: 'Svenska', dateFnsLocale: 'sv' },
  'zh-cn': { label: '简体中文 (Simplified Chinese)', dateFnsLocale: 'zhCN' },
}
Vue.prototype.$languageCodeOptions = Object.keys(languageCodeMap).map(code => {
  return {
    text: languageCodeMap[code].label,
    value: code
  }
})

Vue.prototype.$languageCodes = {
  default: defaultCode,
  current: defaultCode,
  local: null,
  server: null
}

Vue.prototype.$strings = { ...enUsStrings }

Vue.prototype.$getString = (key, subs) => {
  if (!Vue.prototype.$strings[key]) return ''
  if (subs?.length && Array.isArray(subs)) {
    return supplant(Vue.prototype.$strings[key], subs)
  }
  return Vue.prototype.$strings[key]
}

var translations = {
  [defaultCode]: enUsStrings
}

function loadTranslationStrings(code) {
  return new Promise((resolve) => {
    import(`../strings/${code}`).then((fileContents) => {
      resolve(fileContents.default)
    }).catch((error) => {
      console.error('Failed to load i18n strings', code, error)
      resolve(null)
    })
  })
}

async function loadi18n(code) {
  if (!code) return false
  if (Vue.prototype.$languageCodes.current == code) {
    // already set
    return false
  }

  const strings = translations[code] || await loadTranslationStrings(code)
  if (!strings) {
    console.warn(`Invalid lang code ${code}`)
    return false
  }

  translations[code] = strings
  Vue.prototype.$languageCodes.current = code
  localStorage.setItem('lang', code)

  for (const key in Vue.prototype.$strings) {
    Vue.prototype.$strings[key] = strings[key] || translations[defaultCode][key]
  }

  Vue.prototype.$setDateFnsLocale(languageCodeMap[code].dateFnsLocale)

  this.$eventBus.$emit('change-lang', code)
  return true
}

Vue.prototype.$setLanguageCode = loadi18n

// Set the servers default language code, does not override users local language code
Vue.prototype.$setServerLanguageCode = (code) => {
  if (!code) return

  if (!languageCodeMap[code]) {
    console.warn('invalid server language in', code)
  } else {
    Vue.prototype.$languageCodes.server = code
    if (!Vue.prototype.$languageCodes.local && code !== defaultCode) {
      loadi18n(code)
    }
  }
}

// Initialize with language code in localStorage if valid
async function initialize() {
  const localLanguage = localStorage.getItem('lang')
  if (!localLanguage) return

  if (!languageCodeMap[localLanguage]) {
    console.warn('Invalid local language code', localLanguage)
    localStorage.setItem('lang', defaultCode)
  } else {
    Vue.prototype.$languageCodes.local = localLanguage
    loadi18n(localLanguage)
  }
}
initialize()