'use strict'

const path = require('path')
const reader = require('@maxmind/geoip2-node').Reader
const AppConstants = require('./app-constants')

let locationDb, timestamp

async function openLocationDb () {
  if (locationDb && isFresh()) return console.warn('Location database already open.')

  try {
    const dbPath = path.join(AppConstants.GEOIP_GEOLITE2_PATH, AppConstants.GEOIP_GEOLITE2_CITY_FILENAME)
    locationDb = await reader.open(dbPath)
  } catch (e) {
    return console.warn('Could not open location database:', e.message)
  }

  timestamp = Date.now()
  return true
}

async function readLocationData (ip, locales) {
  let locationArr

  if (!isFresh()) await openLocationDb()

  try {
    const data = locationDb.city(ip)
    const countryName = data.country?.names[locales.find(locale => data.country?.names[locale])] // find valid locale key and return its value
    const cityName = data.city?.names[locales.find(locale => data.city?.names[locale])]
    const subdivisionName = data.subdivisions?.[0].isoCode
    const subdivisionFiltered = /[A-z]{2,}/.test(subdivisionName) ? subdivisionName : null // return strings that are 2 or more letters, or null (avoid unfamiliar subdivisions like `E` or `09`)

    locationArr = [cityName, subdivisionFiltered, countryName].filter(str => str) // [city name, state code, country code] with non-null items.
  } catch (e) {
    return console.warn('Could not read location from database:', e.message)
  }

  return {
    shortLocation: locationArr.slice(0, 2).join(', '), // shows the first two location values from the ones available
    fullLocation: locationArr.join(', ') // shows up to three location values from the ones available
  }
}

function isFresh () {
  if (Date.now() - timestamp < 259200000) return true // 1000ms * 60s * 60m * 24h * 3 elapsed time is less than 24hrs
  return false
}

module.exports = {
  openLocationDb,
  readLocationData
}