const fs = require('fs')
const path = require('path')
const { CountryModel, ProvinceModel, CityModel } = require('../models/StateCity')

/**
 * Single source of truth for keeping the Country/Province/City reference
 * collections in sync with data/geo/{countries,provinces,cities}.json.
 * Runs automatically on every backend boot (see boot/mongo.js) — no manual
 * script to remember to re-run when the JSON files change. Cheap no-op when
 * already in sync (only a countDocuments() + JSON parse), unless force=true.
 */
async function ensureGeoData(force = false) {
  const dataDir = path.join(__dirname, '../data/geo')
  const countries = JSON.parse(fs.readFileSync(path.join(dataDir, 'countries.json'), 'utf8'))
  const provinces = JSON.parse(fs.readFileSync(path.join(dataDir, 'provinces.json'), 'utf8'))
  const cities = JSON.parse(fs.readFileSync(path.join(dataDir, 'cities.json'), 'utf8'))

  const provincesWithFaCount = provinces.filter((p) => p.name_fa).length
  const citiesWithFaCount = cities.filter((c) => c.name_fa).length

  const [countryCount, provinceCount, cityCount, provinceFaCount, cityFaCount] = await Promise.all([
    CountryModel.countDocuments(),
    ProvinceModel.countDocuments(),
    CityModel.countDocuments(),
    ProvinceModel.countDocuments({ name_fa: { $exists: true, $ne: null } }),
    CityModel.countDocuments({ name_fa: { $exists: true, $ne: null } })
  ])
  const inSync =
    countryCount === countries.length &&
    provinceCount === provinces.length &&
    cityCount === cities.length &&
    provinceFaCount === provincesWithFaCount &&
    cityFaCount === citiesWithFaCount
  if (!force && inSync) return

  console.log(`[boot] Geo reference data out of sync (countries: ${countryCount}/${countries.length}, provinces: ${provinceCount}/${provinces.length}, cities: ${cityCount}/${cities.length}, city name_fa: ${cityFaCount}/${citiesWithFaCount}) — reseeding...`)

  await CountryModel.deleteMany({})
  await ProvinceModel.deleteMany({})
  await CityModel.deleteMany({})

  await CountryModel.insertMany(countries)
  await ProvinceModel.insertMany(
    provinces.map((p) => ({ id: p.id, name: p.name, name_fa: p.name_fa, slug: p.slug, country_id: p.country_id }))
  )
  await CityModel.insertMany(
    cities.map((c) => ({
      id: c.id,
      name: c.name,
      name_fa: c.name_fa,
      slug: c.slug,
      province_id: c.province_id,
      country_id: c.country_id
    }))
  )

  console.log(`[boot] Geo reference data reseeded: ${countries.length} countries, ${provinces.length} provinces, ${cities.length} cities.`)
}

module.exports = { ensureGeoData }