Initial commit from Create Next App

.env.local.example

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+# Update these with your Firebase app's values.
+FIREBASE_CLIENT_EMAIL=my-example-app-email@example.com
+NEXT_PUBLIC_FIREBASE_PUBLIC_API_KEY=MyExampleAppAPIKey123
+NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN=my-example-app.firebaseapp.com
+NEXT_PUBLIC_FIREBASE_DATABASE_URL=https://my-example-app.firebaseio.com
+NEXT_PUBLIC_FIREBASE_PROJECT_ID=my-example-app-id
+
+# Your Firebase private key.
+FIREBASE_PRIVATE_KEY=some-key-here

.gitignore

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+# See https://help.github.com/articles/ignoring-files/ for more about ignoring files.
+
+# dependencies
+/node_modules
+/.pnp
+.pnp.js
+
+# testing
+/coverage
+
+# next.js
+/.next/
+/out/
+
+# production
+/build
+
+# misc
+.DS_Store
+*.pem
+
+# debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# local env files
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
+
+# vercel
+.vercel

README.md

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+# Example: Firebase authentication with a serverless API
+
+This example includes Firebase authentication and serverless [API routes](https://nextjs.org/docs/api-routes/introduction).
+
+## How to use
+
+Execute [`create-next-app`](https://github.com/vercel/next.js/tree/canary/packages/create-next-app) with [Yarn](https://yarnpkg.com/lang/en/docs/cli/create/) or [npx](https://github.com/zkat/npx#readme) to bootstrap the example:
+
+```bash
+npx create-next-app --example with-firebase-authentication with-firebase-authentication-app
+# or
+yarn create next-app --example with-firebase-authentication with-firebase-authentication-app
+```
+
+## Configuration
+
+Set up Firebase:
+
+- Create a project at the [Firebase console](https://console.firebase.google.com/).
+- Copy the contents of `.env.local.example` into a new file called `.env.local`
+- Get your account credentials from the Firebase console at _Project settings > Service accounts_, where you can click on _Generate new private key_ and download the credentials as a json file. It will contain keys such as `project_id`, `client_email` and `client_id`. Set them as environment variables in the `.env.local` file at the root of this project.
+- Get your authentication credentials from the Firebase console under _Project settings > General> Your apps_ Add a new web app if you don't already have one. Under _Firebase SDK snippet_ choose _Config_ to get the configuration as JSON. It will include keys like `apiKey`, `authDomain` and `databaseUrl`. Set the appropriate environment variables in the `.env.local` file at the root of this project.
+- Go to **Develop**, click on **Authentication** and in the **Sign-in method** tab enable authentication for the app.
+
+Install it and run:
+
+```bash
+npm install
+npm run dev
+# or
+yarn
+yarn dev
+```
+
+Deploy it to the cloud with [Vercel](https://vercel.com/import?filter=next.js&utm_source=github&utm_medium=readme&utm_campaign=next-example) ([Documentation](https://nextjs.org/docs/deployment)).
+
+After deploying, copy the deployment URL and navigate to your Firebase project's Authentication tab. Scroll down in the page to "Authorized domains" and add that URL to the list.

components/FirebaseAuth.js

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+/* globals window */
+import { useEffect, useState } from 'react'
+import StyledFirebaseAuth from 'react-firebaseui/StyledFirebaseAuth'
+import firebase from 'firebase/app'
+import 'firebase/auth'
+import initFirebase from '../utils/auth/initFirebase'
+import { setUserCookie } from '../utils/auth/userCookies'
+import { mapUserData } from '../utils/auth/mapUserData'
+
+// Init the Firebase app.
+initFirebase()
+
+const firebaseAuthConfig = {
+  signInFlow: 'popup',
+  // Auth providers
+  // https://github.com/firebase/firebaseui-web#configure-oauth-providers
+  signInOptions: [
+    {
+      provider: firebase.auth.EmailAuthProvider.PROVIDER_ID,
+      requireDisplayName: false,
+    },
+  ],
+  signInSuccessUrl: '/',
+  credentialHelper: 'none',
+  callbacks: {
+    signInSuccessWithAuthResult: async ({ user }, redirectUrl) => {
+      const userData = mapUserData(user)
+      setUserCookie(userData)
+    },
+  },
+}
+
+const FirebaseAuth = () => {
+  // Do not SSR FirebaseUI, because it is not supported.
+  // https://github.com/firebase/firebaseui-web/issues/213
+  const [renderAuth, setRenderAuth] = useState(false)
+  useEffect(() => {
+    if (typeof window !== 'undefined') {
+      setRenderAuth(true)
+    }
+  }, [])
+  return (
+    <div>
+      {renderAuth ? (
+        <StyledFirebaseAuth
+          uiConfig={firebaseAuthConfig}
+          firebaseAuth={firebase.auth()}
+        />
+      ) : null}
+    </div>
+  )
+}
+
+export default FirebaseAuth

package.json

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+{
+  "name": "with-firebase-authentication",
+  "version": "1.0.0",
+  "scripts": {
+    "dev": "next dev",
+    "build": "next build",
+    "start": "next start"
+  },
+  "dependencies": {
+    "firebase": "^7.15.5",
+    "firebase-admin": "^8.12.1",
+    "js-cookie": "2.2.1",
+    "next": "latest",
+    "react": "^16.13.1",
+    "react-dom": "^16.13.1",
+    "react-firebaseui": "4.1.0",
+    "swr": "0.2.3"
+  },
+  "license": "MIT"
+}

pages/api/getFood.js

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+import { verifyIdToken } from '../../utils/auth/firebaseAdmin'
+const favoriteFoods = ['pizza', 'burger', 'chips', 'tortilla']
+
+const getFood = async (req, res) => {
+  const token = req.headers.token
+
+  try {
+    await verifyIdToken(token)
+    return res.status(200).json({
+      food: favoriteFoods[Math.floor(Math.random() * favoriteFoods.length)],
+    })
+  } catch (error) {
+    return res.status(401).send('You are unauthorised')
+  }
+}
+
+export default getFood

pages/auth.js

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+import FirebaseAuth from '../components/FirebaseAuth'
+
+const Auth = () => {
+  return (
+    <div>
+      <p>Sign in</p>
+      <div>
+        <FirebaseAuth />
+      </div>
+    </div>
+  )
+}
+
+export default Auth

pages/example.js

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+import Link from 'next/link'
+
+const Example = (props) => {
+  return (
+    <div>
+      <p>
+        This page is static because it does not fetch any data or include the
+        authed user info.
+      </p>
+      <Link href={'/'}>
+        <a>Home</a>
+      </Link>
+    </div>
+  )
+}
+
+export default Example

pages/index.js

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+import useSWR from 'swr'
+import Link from 'next/link'
+import { useUser } from '../utils/auth/useUser'
+
+const fetcher = (url, token) =>
+  fetch(url, {
+    method: 'GET',
+    headers: new Headers({ 'Content-Type': 'application/json', token }),
+    credentials: 'same-origin',
+  }).then((res) => res.json())
+
+const Index = () => {
+  const { user, logout } = useUser()
+  const { data, error } = useSWR(
+    user ? ['/api/getFood', user.token] : null,
+    fetcher
+  )
+  if (!user) {
+    return (
+      <>
+        <p>Hi there!</p>
+        <p>
+          You are not signed in.{' '}
+          <Link href={'/auth'}>
+            <a>Sign in</a>
+          </Link>
+        </p>
+      </>
+    )
+  }
+
+  return (
+    <div>
+      <div>
+        <p>You're signed in. Email: {user.email}</p>
+        <p
+          style={{
+            display: 'inline-block',
+            color: 'blue',
+            textDecoration: 'underline',
+            cursor: 'pointer',
+          }}
+          onClick={() => logout()}
+        >
+          Log out
+        </p>
+      </div>
+      <div>
+        <Link href={'/example'}>
+          <a>Another example page</a>
+        </Link>
+      </div>
+      {error && <div>Failed to fetch food!</div>}
+      {data && !error ? (
+        <div>Your favorite food is {data.food}.</div>
+      ) : (
+        <div>Loading...</div>
+      )}
+    </div>
+  )
+}
+
+export default Index

utils/auth/firebaseAdmin.js

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+import * as admin from 'firebase-admin'
+
+export const verifyIdToken = (token) => {
+  const firebasePrivateKey = process.env.FIREBASE_PRIVATE_KEY
+
+  if (!admin.apps.length) {
+    admin.initializeApp({
+      credential: admin.credential.cert({
+        projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
+        clientEmail: process.env.FIREBASE_CLIENT_EMAIL,
+        // https://stackoverflow.com/a/41044630/1332513
+        privateKey: firebasePrivateKey.replace(/\\n/g, '\n'),
+      }),
+      databaseURL: process.env.NEXT_PUBLIC_FIREBASE_DATABASE_URL,
+    })
+  }
+
+  return admin
+    .auth()
+    .verifyIdToken(token)
+    .catch((error) => {
+      throw error
+    })
+}

utils/auth/initFirebase.js

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+import firebase from 'firebase/app'
+import 'firebase/auth'
+
+const config = {
+  apiKey: process.env.NEXT_PUBLIC_FIREBASE_PUBLIC_API_KEY,
+  authDomain: process.env.NEXT_PUBLIC_FIREBASE_AUTH_DOMAIN,
+  databaseURL: process.env.NEXT_PUBLIC_FIREBASE_DATABASE_URL,
+  projectId: process.env.NEXT_PUBLIC_FIREBASE_PROJECT_ID,
+}
+
+export default function initFirebase() {
+  if (!firebase.apps.length) {
+    firebase.initializeApp(config)
+  }
+}

utils/auth/mapUserData.js

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+export const mapUserData = (user) => {
+  const { uid, email, xa, ya } = user
+  return {
+    id: uid,
+    email,
+    token: xa || ya,
+  }
+}

utils/auth/useUser.js

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+import { useEffect, useState } from 'react'
+import { useRouter } from 'next/router'
+import firebase from 'firebase/app'
+import 'firebase/auth'
+import initFirebase from '../auth/initFirebase'
+import {
+  removeUserCookie,
+  setUserCookie,
+  getUserFromCookie,
+} from './userCookies'
+import { mapUserData } from './mapUserData'
+
+initFirebase()
+
+const useUser = () => {
+  const [user, setUser] = useState()
+  const router = useRouter()
+
+  const logout = async () => {
+    return firebase
+      .auth()
+      .signOut()
+      .then(() => {
+        // Sign-out successful.
+        router.push('/auth')
+      })
+      .catch((e) => {
+        console.error(e)
+      })
+  }
+
+  useEffect(() => {
+    // Firebase updates the id token every hour, this
+    // makes sure the react state and the cookie are
+    // both kept up to date
+    const cancelAuthListener = firebase.auth().onIdTokenChanged((user) => {
+      if (user) {
+        const userData = mapUserData(user)
+        setUserCookie(userData)
+        setUser(userData)
+      } else {
+        removeUserCookie()
+        setUser()
+      }
+    })
+
+    const userFromCookie = getUserFromCookie()
+    if (!userFromCookie) {
+      router.push('/')
+      return
+    }
+    setUser(userFromCookie)
+
+    return () => {
+      cancelAuthListener()
+    }
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [])
+
+  return { user, logout }
+}
+
+export { useUser }

utils/auth/userCookies.js

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+import cookies from 'js-cookie'
+
+export const getUserFromCookie = () => {
+  const cookie = cookies.get('auth')
+  if (!cookie) {
+    return
+  }
+  return JSON.parse(cookie)
+}
+
+export const setUserCookie = (user) => {
+  cookies.set('auth', user, {
+    // firebase id tokens expire in one hour
+    // set cookie expiry to match
+    expires: 1 / 24,
+  })
+}
+
+export const removeUserCookie = () => cookies.remove('auth')