import { createI18n } from 'vue-i18n'
import en from './en.json'
import zhTW from './zh-TW.json'
import ja from './ja.json'

export type MessageSchema = typeof en

const supportedLanguages = {
  'en': en,
  'zh-TW': zhTW,
  'ja': ja,
}

function detectInitialLanguage(): string {
  const saved = localStorage.getItem('app_language')
  if (saved && saved in supportedLanguages) {
    return saved
  }
  
  if (saved === 'auto') {
    return detectOSLanguage()
  }
  
  return 'en'
}

function detectOSLanguage(): string {
  let osLang = 'en'
  
  try {
    if ((window as any).__TAURI__) {
      const locale = (window as any).__TAURI__?.os?.getLocale?.()
      if (locale) osLang = locale
    } else {
      osLang = navigator.language || 'en'
    }
  } catch (e) {
    console.error('Language detection failed:', e)
  }
  
  if (osLang.startsWith('zh-TW') || osLang.startsWith('zh-Hant')) {
    return 'zh-TW'
  } else if (osLang.startsWith('zh-CN') || osLang.startsWith('zh-Hans')) {
    return 'zh-CN'
  } else if (osLang.startsWith('ja')) {
    return 'ja'
  } else if (osLang.startsWith('ko')) {
    return 'ko'
  }
  
  return 'en'
}

const i18n = createI18n<[MessageSchema], 'en' | 'zh-TW' | 'ja'>({
  legacy: false,
  locale: detectInitialLanguage(),
  fallbackLocale: 'en',
  messages: supportedLanguages as any,
  missingWarn: false,
  fallbackWarn: false,
})

export function changeLanguage(lang: string) {
  if (lang === 'auto') {
    localStorage.setItem('app_language', 'auto')
    const detected = detectOSLanguage()
    i18n.global.locale = detected as any
  } else {
    localStorage.setItem('app_language', lang)
    i18n.global.locale = lang as any
  }
}

export function getCurrentLanguage(): string {
  return i18n.global.locale as string
}

export { detectOSLanguage }
export default i18n