import { get } from 'lodash-es'

import zh from './languages/zh.json'
import en from './languages/en.json'
import { reactive } from 'vue'

const Languages = {
  zh: zh,
  en: en
}

export type LanguagesType = keyof typeof Languages

const LocaleState = reactive<{
  locale: LanguagesType
}>({
  locale: 'zh'
})

type FlattenObject<T, Prefix extends string = ''> = T extends object
  ? {
      [K in keyof T & (string | number)]: FlattenObject<
        T[K],
        Prefix extends '' ? `${K}` : `${Prefix}.${K}`
      >
    }[keyof T & (string | number)]
  : Prefix

type FlattenKeys<T> = FlattenObject<T>

type TranslationKey = FlattenKeys<typeof zh>

function useLocale() {
  function setLocale(locale: LanguagesType) {
    LocaleState.locale = locale
  }

  function getLocale(): string {
    return LocaleState.locale
  }

  function t(key: TranslationKey, replacements?: Record<string, string>): string {
    let text: string =
      LocaleState.locale in Languages
        ? get(Languages[LocaleState.locale], key)
        : get(Languages['zh'], key)
    if (!text) {
      text = get(Languages['zh'], key)
      if (!text) {
        return key
      }
    }
    if (replacements) {
      Object.entries(replacements).forEach(([key, value]) => {
        text = text.replace(new RegExp(`{${key}}`, 'g'), value)
      })
    }
    return text
  }

  return {
    setLocale,
    getLocale,
    t
  }
}

export { useLocale }