Authentication issues

auth.js

const AUTH_URL = 'https://smartweather.weatherflow.com/authorize.html'

export const toAuthUrl = ({
  clientId: client_id,
  codeChallenge: code_challenge,
}) => {
  const params = {
    response_type: 'code',
    redirect_uri: '<REDIRECT_URL>',
    code_challenge_method: 'S256',
    client_id,
    code_challenge,
  }
  const queryString = new URLSearchParams(params).toString()

  return `${AUTH_URL}?${queryString}`
}

code.js

export const genVerifier = () =>
  self.crypto.getRandomValues(new Uint16Array(10)).join('')

export const toCodeChallenge = async (message) => {
  const data = new TextEncoder().encode(message)
  const hash = await crypto.subtle.digest('SHA-256', data)
  return base64UrlEncode(new Uint8Array(hash))
}

const base64UrlEncode = (data) =>
  btoa(String.fromCharCode.apply(null, data))
    .replace(/\+/g, '-')
    .replace(/\//g, '_')
    .replace(/=/g, '')

index.js

import { genVerifier, toCodeChallenge } from './code.js'
import { toAuthUrl } from './auth.js'
import { toToken } from './token.js'

const CLIENT_ID = <CLIENT_ID>

;(async () => {
  const codeVerifier = genVerifier()
  const codeChallenge = await toCodeChallenge(codeVerifier)
  
  const authUrl = toAuthUrl({ clientId: CLIENT_ID, codeChallenge })
  document.getElementById('authorize').setAttribute('href', authUrl)

  const code = new URLSearchParams(window.location.search).get('code') ?? ''
  if (code) {
    const token = await toToken({ clientId: CLIENT_ID, codeVerifier, code })
    console.log(token)
  }
})()

token.js

const TOKEN_URL = 'https://swd.weatherflow.com/id/oauth2/token'

export const toToken = async ({
  clientId: client_id,
  codeVerifier: code_verifier,
  code,
}) =>
  (
    await fetch(TOKEN_URL, {
      method: 'POST',
      body: new URLSearchParams({
        grant_type: 'authorization_code',
        client_id,
        code_verifier,
        code,
      }),
    })
  ).json()