'use strict'

const fsp = require('fs').promises
const path = require('path')
const { DIRS } = require('./paths')

const FALLBACK = 'en-us'
let cache = {}

async function loadLang(code) {
  const file = path.join(DIRS.TRANSLATIONS, `${code}.json`)
  try {
    const raw = await fsp.readFile(file, 'utf8')
    const parsed = JSON.parse(raw)
    cache[code] = parsed
    return parsed
  } catch {
    return null
  }
}

async function init() {
  const files = await fsp.readdir(DIRS.TRANSLATIONS).catch(() => [])
  const langs = []
  for (const f of files) {
    if (!f.endsWith('.json')) continue
    const lang = await loadLang(f.replace(/\.json$/, ''))
    if (lang && lang.data && lang.texts) langs.push(lang)
  }
  return langs
}

function listLangs() {
  return Object.entries(cache).map(([code, lang]) => ({
    code,
    nameEn: (lang.data && lang.data.nameEn) || code,
    nameSelf: (lang.data && lang.data.nameSelf) || code
  }))
}

function getLang(code) {
  return cache[code] || cache[FALLBACK] || { texts: {}, data: {} }
}

function translate(code, key, ...args) {
  const lang = getLang(code)
  let text = (lang.texts && lang.texts[key]) ?? (cache[FALLBACK] && cache[FALLBACK].texts && cache[FALLBACK].texts[key]) ?? key
  args.forEach((v, i) => {
    text = String(text).split(`{${i}}`).join(String(v))
  })
  return text
}

module.exports = { init, listLangs, getLang, translate, loadLang, FALLBACK }