Uses Cloudflare KV data store & Google ReCaptcha!

cloudflare-workers-signup-endpoint.js

// Note to self: Currently running here: https://dash.cloudflare.com/eb29900091c43bef22edfb71df934698/workers/edit/fanclub

/*
## Utility Functions
*/
const isEmailShaped = email => email && email.length > 5 && email.indexOf('@') > -1

const sendJSON = (data, status = 200) => new Response(
  typeof data !== 'string' ? JSON.stringify(data) : data, {
    headers: { 'Content-Type': 'application/json; charset=UTF-8' },
    status
  })

/*
## Data Methods
*/
const usersDB = {
  async find(key) {
    const result = await FANCLUB.get(key)
    return result && result.length >= 1 ? JSON.parse(result) : result
  },
  async create({name, email, ip, originalReferer, referer}) {
    return FANCLUB.put(email, JSON.stringify({name, email, ip, originalReferer, referer, verified: false}))
  },
  async list({ limit = 100 } = {}) {
    const results = await FANCLUB.list({ limit })
    return (results && results.keys).map(o => o.name)
  }
}

/*
## Request Handlers
*/
const handlers = {

  async listUsers(request) {
    const keyList = await usersDB.list({ limit: 100 })
    return sendJSON(keyList)
  },

  async signupUser(request) {
    try {
      const secret = await CONFIG.get('RECAPTCHA_SECRET')
      const ip = request.headers.get('CF-Connecting-IP')
      const body = JSON.parse(await request.text())
      const {name, email, originalReferer, referer} = body
      const {recaptcha} = body

      if (!isEmailShaped(email)) throw new Error('Invalid email agument')
      if (! (await verifyReCaptcha({response: recaptcha, remoteip: ip, secret}))) throw new Error('Verify Captcha & try again')
      if (await usersDB.find(email)) throw new Error('Email already registered!')

      await usersDB.create({name, email, ip, originalReferer, referer, verified: false})
      return sendJSON({message: `Successfully registered ${name}`})
    } catch (err) {
      return sendJSON({message: err.message, stack: err.stack}, 500)
    }
  }
}

/*
## ReCaptcha Dependency
More info: https://developers.google.com/recaptcha/docs/verify#api_request
*/
async function verifyReCaptcha({response, remoteip, secret}) {
  if (!secret) throw new Error('Admin Error: Please configure required server variable `RECAPTCHA_SECRET`.')
  if (!response) throw new Error('API Error: Missing parameter `recaptcha` or `response`.')

  return fetch(`https://www.google.com/recaptcha/api/siteverify`, {
    method: 'POST',
    body: new URLSearchParams({secret, response, remoteip}).toString()
  })
  .then(response => response.json())
  .then(data => {
    console.info('recaptcha response:', data)
    if (!data || !data.success) return false
    return {message: `successfully verified captcha`, ...data, success: data.success}
  })
}

/*
## Cloudflare Tie-in
*/
async function handleRequest(request) {
  if (typeof CONFIG === 'undefined' || typeof FANCLUB === 'undefined') return sendJSON({message: 'System Error: Key-value stores not configured.'})

  if (request.method === 'GET') {
    console.error('WARNING: DATA LEAK HERE!!!! REMOVE IN PROD!')
    return handlers.listUsers(request)
  } else if (request.method === 'POST') {
    return handlers.signupUser(request)
  } else {
    return sendJSON({message: 'The specified http path & method not supported.'}, 400)
  }
}

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request))
})