Firebase function to list provider logins past month

provider.ts

import * as functions from "firebase-functions"
import * as admin from "firebase-admin"

const getUsers = async (pageToken?: string) : Promise<admin.auth.UserRecord[]> => {
  const result = await admin.auth().listUsers(1000, pageToken)
  if (result.pageToken) {
    return [...result.users, ...await getUsers(result.pageToken)]
  }
  return result.users
}

const publish = functions.https.onRequest(async (req, res) => {
  const users = await getUsers()
  const logins = users.map(user => {
    return { lastSignIn: new Date(Date.parse(user.metadata.lastSignInTime)), providerId: user.providerData[0].providerId }
  })
  const providers = Array.from(new Set(logins.map(login => login.providerId)))
  const oneMonthAgo = new Date()
  oneMonthAgo.setMonth(oneMonthAgo.getMonth() - 1)
  const providerLogins = providers.map(provider => {
    return { provider, pastMonth: logins.filter(login => login.providerId === provider && login.lastSignIn >= oneMonthAgo).length }
  });
  const data = { providerLogins }
  res.send(data)
  res.end()
})

export = publish;