tokens.js

import dotenv from "dotenv"
const storedEnv = dotenv.config()
import fs from "node:fs/promises"
import { parse, stringify } from "envfile"

const sourcePath = '.env'

// https://stackoverflow.com/a/69058154/1413302
const isTokenExpired = (token) => (Date.now() >= JSON.parse(Buffer.from(token.split('.')[1], 'base64').toString()).exp * 1000)

/**
 * Use the privately stored refresh token to generate a new access token for
 * your RERUM-connected application. There is no way to authenticate this 
 * process, so protect your refresh token and replace it if it is exposed. 
 * NOTE: This fails without updating or throwing an error.
 */
async function generateNewAccessToken() {
    const tokenObject = await fetch(process.env.RERUM_ACCESS_TOKEN_URL, {
        method: 'POST',
        headers: {
            'Content-Type': 'application/json',
        },
        body: JSON.stringify({ "refresh_token": process.env.REFRESH_TOKEN }),
        timeout: 10000,
    }).then(res => res.json())
        .catch(err => console.error("Access token not updated: ", err))
    process.env.ACCESS_TOKEN = tokenObject.access_token
    try {
        const data = await fs.readFile('./.env', { encoding: 'utf8' })
        // Please note that this parse() will remove all #comments in the .env file.
        const env_file_obj = parse(data)
        env_file_obj.ACCESS_TOKEN = tokenObject.access_token
        await fs.writeFile('./.env', stringify(env_file_obj))
        console.log("TinyNode now has an updated access token.")
    }
    catch (env_error) {
        console.error("Could not write new token property to the file.  The access token has not been updated.")
        console.error(env_error)
    }
}

/**
 * This will conduct a simple check against the expiry date in your token.
 * This does not validate your access token, so you may still be rejected by 
 * your RERUM instance as unauthorized.
 */
function updateExpiredToken() {
    if (isTokenExpired(process.env.ACCESS_TOKEN)) {
        console.log("TinyNode detected an expired access token.  Updating the token now.")
        generateNewAccessToken()
    }
    else{
        console.log("TinyNode token is up to date")
    }
}

export {updateExpiredToken}