import Vue from 'vue'
import VueI18n from 'vue-i18n'
import ko from '@/locales/ko.json'
import en from '@/locales/en.json'
import ja from '@/locales/ja.json'

Vue.use(VueI18n)

function detectLocale() {
  try {
    const saved = localStorage.getItem('locale')
    if (saved) return saved
  } catch (e) {
    // ignore
  }

  const list = (navigator.languages && navigator.languages.length
    ? navigator.languages
    : [navigator.language || 'en'])
    .map(l => String(l).toLowerCase())

  for (const l of list) {
    if (l.startsWith('ko')) return 'ko'
    if (l.startsWith('ja')) return 'ja'
    if (l.startsWith('en')) return 'en'
  }
  return 'en' // 매칭 실패 시 기본값
}

const i18n = new VueI18n({
  locale: detectLocale(),
  fallbackLocale: 'en',
  messages: { ko, en, ja },
  // 숫자/통화 포맷 정책
  numberFormats: {
    en: {
      decimal: {
        style: 'decimal',
        minimumFractionDigits: 0,
        maximumFractionDigits: 2
      },
      currency: {
        style: 'currency',
        currency: 'USD',
        currencyDisplay: 'symbol',
        minimumFractionDigits: 2,
        maximumFractionDigits: 2
      }
    },
    ko: {
      decimal: {
        style: 'decimal',
        minimumFractionDigits: 0,
        maximumFractionDigits: 2
      },
      currency: {
        style: 'currency',
        currency: 'KRW',
        currencyDisplay: 'symbol',
        minimumFractionDigits: 0,
        maximumFractionDigits: 0
      }
    },
    ja: {
      decimal: {
        style: 'decimal',
        minimumFractionDigits: 0,
        maximumFractionDigits: 2
      },
      currency: {
        style: 'currency',
        currency: 'JPY',
        currencyDisplay: 'symbol',
        minimumFractionDigits: 0,
        maximumFractionDigits: 0
      }
    }
  },
  // 날짜/시간 포맷(예시)
  dateTimeFormats: {
    en: {
      short: {
        year: 'numeric', month: '2-digit', day: '2-digit'
      }
    },
    ko: {
      short: {
        year: 'numeric', month: '2-digit', day: '2-digit'
      }
    },
    ja: {
      short: {
        year: 'numeric', month: '2-digit', day: '2-digit'
      }
    }
  },
  silentTranslationWarn: process.env.NODE_ENV === 'production',
  missing(locale, key) {
    if (process.env.NODE_ENV !== 'production') {
      // eslint-disable-next-line no-console
      console.warn(`[i18n missing] ${locale}: ${key}`)
    }
  }
})

export default i18n