spotify_token_cloudflare_worker.js

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

function makeErrorResponse(message) {
  return new Response(message, {
    status: 404,
    statusText: 'not found',
    headers: {
      'content-type': 'text/plain',
    },
  })
}

async function swap(request) {
  const requestData = await request.formData()
  const body = {}
  for (const entry of requestData.entries()) {
    body[entry[0]] = entry[1]
  }
  const requestCode = body["code"]
  if (requestCode == undefined) { 
    return makeErrorResponse("no required code parameter")
  }
  const grantData = 'grant_type=authorization_code'
  const redirectData = 'redirect_uri=' + SPOTIFY_REDIRECT_URI
  const codeData = 'code=' + requestCode
  const clientIdData = 'client_id=' + SPOTIFY_CLIENT_ID
  const clientSecretData = 'client_secret=' + SPOTIFY_CLIENT_SECRET
  const spotifyRequestBody = grantData + '&' 
  + redirectData + '&' 
  + codeData + '&' 
  +  clientIdData + '&' + 
  clientSecretData
  const init = {
    body: spotifyRequestBody,
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded"
    }
  }
  const url = 'https://accounts.spotify.com/api/token'
  const spotifyResponse = await fetch(url, init)
  if (spotifyResponse.status != 200) {
    const errorResponse = await spotifyResponse.text();
    return makeErrorResponse("Spotify returned error: " + errorResponse)
  }
  const spotifyJSON = await spotifyResponse.json()
  refreshToken = spotifyJSON["refresh_token"]
  const encryptedRefreshToken = await encrypt(refreshToken)
  spotifyJSON["refresh_token"] = encryptedRefreshToken
  const responseBody = JSON.stringify(spotifyJSON)
  return new Response(responseBody)
}

async function refresh(request) {
  const requestData = await request.formData()
  const body = {}
  for (const entry of requestData.entries()) {
    body[entry[0]] = entry[1]
  }
  const encryptedRefreshToken = body["refresh_token"]
  if (encryptedRefreshToken == undefined) {
    return makeErrorResponse("no required code parameter")
  }
  const encryptedRefreshTokenFixed = encryptedRefreshToken.replaceAll(" ", "+")
  const refreshToken = await decrypt(encryptedRefreshTokenFixed)
  const grantData = 'grant_type=refresh_token'
  const refreshTokenData = 'refresh_token=' + refreshToken
  const spotifyRequestBody = grantData + '&' + refreshTokenData
  const authorizationHeader = SPOTIFY_CLIENT_ID + ":" + SPOTIFY_CLIENT_SECRET
  const base64Header = btoa(authorizationHeader)
  const init = {
    body: spotifyRequestBody,
    method: "POST",
    headers: {
      "Content-Type": "application/x-www-form-urlencoded",
      "Authorization": "Basic " + base64Header
    }
  }
  const url = 'https://accounts.spotify.com/api/token'
  const spotifyResponse = await fetch(url, init)
  if (spotifyResponse.status != 200) {
    const errorResponse = await spotifyResponse.text();
    return makeErrorResponse("Spotify returned error: " + errorResponse)
  }
  const spotifyJSON = await spotifyResponse.json()
  const responseBody = JSON.stringify(spotifyJSON)
  return new Response(responseBody)
}

async function encrypt(decryptedMessage) {
  // TODO: put your encryption here. Cloudflare Workers support WebCrypto API
  return encryptedBase64
}

async function decrypt(encryptedBase64) {
  // TODO: put your decryption here. Cloudflare Workers support WebCrypto API
  return decryptedMessage
}


/**
 * Respond to the request
 * @param {Request} request
 */
 async function handleRequest(request) {

  const url = new URL(request.url)
  var path = url.pathname

  switch (path) {

    case "/swap":
    case "swap": 
    if (request.method != "POST") {
      return makeErrorResponse("this endpoint only takes POST!")
    }
    return await swap(request)
    
    case "/refresh":
    case "refresh":
    if (request.method != "POST") {
      return makeErrorResponse("this endpoint only takes POST!")
    }
    return await refresh(request)
    
    default:
    return makeErrorResponse("endpoint not found")
  }

}