update-csv.js

var c2j = require('csv-to-json')
var j2c = require('json-to-csv')
var fs = require('fs')
var apiKeys = JSON.parse(fs.readFileSync('apiKeys.json', 'utf8'))
var gMaps = require('@google/maps').createClient({
  key: apiKeys.gMapsKey,
  Promise: Promise // 'Promise' is the native constructor.
})
var toSleep = 50
const outputFileName = 'formatted.csv'

var fileObj = {
  filename: 'CarParkRates.csv'
}

var parseCallback = function (err, json) {
    // finds coordinates via maps and writes to new file
  if (err) {
    console.log(err)
  } else {
    findCoordViaMap(json)
  }
}

function findCoordViaMap (carparks) {
  var promises = []
  var computedCarparks = []
  for (var i = 0; i < carparks.length; i++) {
    if (carparks[i].CarPark !== '') {
      var newPromise = gMaps.geocode({address: carparks[i].CarPark, region: 'sg'}).asPromise()
      promises.push(newPromise)
      // console.log('request number ', i, ' made');
      sleep(toSleep)
    }
  }

  Promise.all(promises).then(values => {
    for (var i = 0; i < values.length; i++) {
      var result = values[i]
      for (var j = 0; j < carparks.length; j++) {
        var carpark = carparks[j]
        if (carpark.CarPark === result.query.address) {
          var newJson = getCarparkJson(carpark, result)
          if (!isEmpty(newJson)) {
            computedCarparks.push(newJson)
          }
        }
      }
    }
    // console.log(computedCarparks)
    // write json to new file
    writeToFile(computedCarparks)
  }).catch(function (err) {
    console.log(err) // some coding error in handling happened
  })
}

function writeToFile (carparks) {
  // write to JSON file (to be deprecated)
  var uniqueCarparks = arrUnique(carparks)
  var writeObj = {
    filename: 'rates.json',
    json: uniqueCarparks
  }

  var writeCallback = function (err) {
    if (err !== 'null') {
      console.log('JSON success!')
    } else {
      console.log(err)
    }
  }
  c2j.writeJsonToFile(writeObj, writeCallback)

  j2c(uniqueCarparks, outputFileName)
    .then(() => {
      console.log('CSV Success')
    })
    .catch(err => {
      console.log('CSV ERROR')
      console.log(err)
    })
}

function getCarparkJson (carpark, result) {
  if (result.json.results.length > 0) {
    return {
      CarPark: carpark.CarPark,
      // category causes duplication issues
      // Category: carpark.Category,
      Address: result.json.results[0].formatted_address,
      Location_Lat: result.json.results[0].geometry.location.lat,
      Location_Lng: result.json.results[0].geometry.location.lng,
      WeekDays_Rate_1: carpark.WeekDays_Rate_1,
      WeekDays_Rate_2: carpark.WeekDays_Rate_2,
      Saturday_Rate: carpark.Saturday_Rate,
      Sunday_PublicHoliday_Rate: carpark.Sunday_PublicHoliday_Rate,
      Lot_Avail_ID: '-'
    }
  } else {
    console.log(result)
    return {
    }
  }
}

c2j.parse(fileObj, parseCallback)

// funciton to sleep to avoid flooding google maps
function sleep (milliseconds) {
  var start = new Date().getTime()
  for (var i = 0; i < 1e7; i++) {
    if ((new Date().getTime() - start) > milliseconds) {
      break
    }
  }
}

function isEmpty (obj) {
  return JSON.stringify(obj) === JSON.stringify({})
}

function arrUnique (obj) {
  var uniques = []
  var stringify = {}
  for (var i = 0; i < obj.length; i++) {
    var keys = Object.keys(obj[i])
    keys.sort(function (a, b) { return a - b })
    var str = ''
    for (var j = 0; j < keys.length; j++) {
      str += JSON.stringify(keys[j])
      str += JSON.stringify(obj[i][keys[j]])
    }
    if (!stringify.hasOwnProperty(str)) {
      uniques.push(obj[i])
      stringify[str] = true
    }
  }
  return uniques
}