Functions Samples Authorized HTTPS Endpoint TypeScript版

FirebaseはいくつかのサンプルをJavaScriptで公開してくれています🙏
そのサンプルの中のAuthorized HTTPS EndpointをTypeScriptで使いたかったので書き直してみました。

参考URL:
https://github.com/firebase/functions-samples/tree/master/authorized-https-endpoint
https://stackoverflow.com/questions/44383387/typescript-error-property-user-does-not-exist-on-type-request

/**
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License")
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import * as admin from 'firebase-admin'
import * as express from 'express'
import * as cookieParser from 'cookie-parser'
import * as cors from 'cors'

const app = express()

admin.initializeApp()

export interface AuthRequest extends express.Request {
  user?: admin.auth.DecodedIdToken
}

const validateFirebaseIdToken = async (req: AuthRequest, res: express.Response, next: express.NextFunction) => {
  console.log('Check if request is authorized with Firebase ID token')

  if ((!req.headers.authorization || !req.headers.authorization.startsWith('Bearer ')) &&
      !(req.cookies && req.cookies.__session)) {
    console.error('No Firebase ID token was passed as a Bearer token in the Authorization header.',
        'Make sure you authorize your request by providing the following HTTP header:',
        'Authorization: Bearer <Firebase ID Token>',
        'or by passing a "__session" cookie.')
    res.status(403).send('Unauthorized')
    return
  }

  let idToken
  if (req.headers.authorization && req.headers.authorization.startsWith('Bearer ')) {
    console.log('Found "Authorization" header')
    idToken = req.headers.authorization.split('Bearer ')[1]
  } else if(req.cookies) {
    console.log('Found "__session" cookie')
    idToken = req.cookies.__session
  } else {
    res.status(403).send('Unauthorized')
    return
  }

  try {
    const decodedIdToken = await admin.auth().verifyIdToken(idToken)
    console.log('ID Token correctly decoded', decodedIdToken)
    req.user = decodedIdToken
    next()
    return
  } catch (error) {
    console.error('Error while verifying Firebase ID token:', error)
    res.status(403).send('Unauthorized')
    return
  }
}

app.use(cors({origin: true}))
app.use(cookieParser())
app.use(validateFirebaseIdToken)
app.get('/hello', (req: AuthRequest, res: express.Response) => {
  res.send(`Hello ${req.user?.name}`)
})


// This HTTPS endpoint can only be accessed by your Firebase Users.
// Requests need to be authorized by providing an `Authorization` HTTP header
// with value `Bearer <Firebase ID Token>`.
exports.app = functions.https.onRequest(app)