// Usage: node scripts/add_user_count_to_csv.js [OPTS] [INPUT-FILE]
// Looks up the number of users for each domain in the input csv file and adds
// columns for the number of users in the domain, subdomains, and total.
const fs = require('fs')
const csv = require('csv/sync')
const minimist = require('minimist')
const UserGetter = require('../app/src/Features/User/UserGetter')
const { db, waitForDb } = require('../app/src/infrastructure/mongodb')
const _ = require('lodash')

const argv = minimist(process.argv.slice(2), {
  string: ['domain', 'output'],
  boolean: ['help'],
  alias: {
    domain: 'd',
    output: 'o',
  },
  default: {
    domain: 'Email domain',
    output: '/dev/stdout',
  },
})

if (argv.help || argv._.length > 1) {
  console.error(`Usage: node scripts/add_user_count_to_csv.js [OPTS] [INPUT-FILE]
    Looks up the number of users for each domain in the input file and adds
    columns for the number of users in the domain, subdomains, and total.

    Options:

        --domain    name of the csv column containing the email domain (default: "Email domain")
        --output    output file (default: /dev/stdout)
    `)
  process.exit(1)
}

const input = fs.readFileSync(argv._[0], 'utf8')
const records = csv.parse(input, { columns: true })

if (records.length === 0) {
  console.error('No records in input file')
  process.exit(1)
}

async function main() {
  await waitForDb()
  for (const record of records) {
    const domain = record[argv.domain]
    const { domainUserCount, subdomainUserCount } = await getUserCount(domain, {
      _id: 1,
    })
    record['Domain Users'] = domainUserCount
    record['Subdomain Users'] = subdomainUserCount
    record['Total Users'] = domainUserCount + subdomainUserCount
  }
  const output = csv.stringify(records, { header: true })
  fs.writeFileSync(argv.output, output)
}

async function getUserCount(domain) {
  const domainUsers = await UserGetter.promises.getUsersByHostname(domain, {
    _id: 1,
  })
  const subdomainUsers = await getUsersByHostnameWithSubdomain(domain, {
    _id: 1,
  })
  return {
    domainUserCount: domainUsers.length,
    subdomainUserCount: subdomainUsers.length,
  }
}

async function getUsersByHostnameWithSubdomain(domain, projection) {
  const reversedDomain = domain.trim().split('').reverse().join('')
  const reversedDomainRegex = _.escapeRegExp(reversedDomain)
  const query = {
    emails: { $exists: true },
    // look for users in subdomains of a domain, but not the domain itself
    // e.g. for domain 'foo.edu', match 'cs.foo.edu' but not 'foo.edu'
    // we use the reversed hostname index to do this efficiently
    // we need to escape the domain name to prevent '.' from matching any character
    'emails.reversedHostname': { $regex: '^' + reversedDomainRegex + '\\.' },
  }
  return await db.users.find(query, { projection }).toArray()
}

main()
  .then(() => {
    console.error('Done')
    process.exit(0)
  })
  .catch(err => {
    console.error(err)
    process.exit(1)
  })