store access token and refresh token in the file system /tmp

utils/accessTokenHandler.ts

@@ -1,24 +1,22 @@
 import axios from 'axios'
 import CryptoJS from 'crypto-js'
-import Keyv from 'keyv'
-import KeyvFile from 'keyv-file'
 
 import apiConfig from '../config/api.json'
 
+// Just a disguise to obfuscate the client secret, used along with the following two functions
 const AES_SECRET_KEY = 'onedrive-vercel-index'
-
-export function obfuscateToken(token: string): string {
+function obfuscateToken(token: string): string {
   // Encrypt token with AES
   const encrypted = CryptoJS.AES.encrypt(token, AES_SECRET_KEY)
   return encrypted.toString()
 }
-
 export function revealObfuscatedToken(obfuscated: string): string {
   // Decrypt SHA256 obfuscated token
   const decrypted = CryptoJS.AES.decrypt(obfuscated, AES_SECRET_KEY)
   return decrypted.toString(CryptoJS.enc.Utf8)
 }
 
+// Generate the Microsoft OAuth 2.0 authorization URL, used for requesting the authorisation code
 export function generateAuthorisationUrl(): string {
   const { clientId, redirectUri, authApi } = apiConfig
   const authUrl = authApi.replace('/token', '/authorize')
@@ -34,6 +32,8 @@ export function generateAuthorisationUrl(): string {
   return `${authUrl}?${params.toString()}`
 }
 
+// The code returned from the Microsoft OAuth 2.0 authorization URL is a request URL with hostname
+// http://localhost and URL parameter code. This function extracts the code from the request URL
 export function extractAuthCodeFromRedirected(url: string): string {
   // Return empty string if the url is not the defined redirect uri
   if (!url.startsWith(apiConfig.redirectUri)) {
@@ -45,6 +45,9 @@ export function extractAuthCodeFromRedirected(url: string): string {
   return params.get('code') || ''
 }
 
+// After a successful authorisation, the code returned from the Microsoft OAuth 2.0 authorization URL
+// will be used to request an access token. This function requests the access token with the authorisation code
+// and returns the access token and refresh token on success.
 export async function requestTokenWithAuthCode(
   code: string
 ): Promise<
@@ -78,8 +81,3 @@ export async function requestTokenWithAuthCode(
       return { error, errorDescription: error_description, errorUri: error_uri }
     })
 }
-
-export function storeTokens(accessToken: string, refreshToken: string) {
-  // We can safely leverage Vercel's /tmp directory, and persist the tokens with file-system based KV storage
-  const kv = new Keyv({ store: new KeyvFile(), namespace: 'onedrive-vercel-index' })
-}

utils/odAuthTokenStore.ts

@@ -0,0 +1,32 @@
+// This should be only used on the server side, where the tokens are stored with KV store using
+// a file system based storage. The tokens are stored in the file system as JSON at /tmp path.
+
+import Keyv from 'keyv'
+import { KeyvFile } from 'keyv-file'
+
+const kv = new Keyv({
+  store: new KeyvFile(),
+})
+
+export async function storeOdAuthTokens({
+  accessToken,
+  accessTokenExpiry,
+  refreshToken,
+}: {
+  accessToken: string
+  accessTokenExpiry: number
+  refreshToken: string
+}): Promise<void> {
+  await kv.set('access_token', accessToken, accessTokenExpiry)
+  await kv.set('refresh_token', refreshToken)
+}
+
+export async function getOdAuthTokens(): Promise<{ accessToken: unknown; refreshToken: unknown }> {
+  const accessToken = await kv.get('access_token')
+  const refreshToken = await kv.get('refresh_token')
+
+  return {
+    accessToken,
+    refreshToken,
+  }
+}