328 lines
9.1 KiB
Markdown
328 lines
9.1 KiB
Markdown
### OAuth2 purpose
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A way for the `user` to tell `google` to give an access to `xorismesiti.gr` app
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<br>
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### Flow:
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| When | What | How |
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|-------|--------------------------|--------------------------------------------------|
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| 1 | Get Code | ` Front ⇢ Google ⇢ Back `|
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| 2 | Exchange Code with Token | ` Back ⇢ Google ⇢ Back ⇢ Front `|
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| 4 | Use Token | ` Front ⇢ Back ⇢ Google ⇢ Back ⇢ Front `|
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<br>
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### Details:
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1. Get Code
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1. Frontend **GET** to Google `https://accounts.google.com/o/oauth2` with callback url
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2. Google **302** to Backend `https://xorismesiti.gr/api/auth/callback` with authorization code
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2. Exchange Code with Token
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1. Backend **POST** the `code` to Google `https://oauth2.googleapis.com/token`
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2. Google **response** to Backend with an `access_token` and a `refresh token`
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3. Backend **response** to Frontend with the `access_token` in a `cookie`
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3. Use Token
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1. Frontend **GET** profile data from Backend `https://xorismesiti.gr/api/auth/profile` using the `cookie`
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2. Backend **GET** profile data from Google `https://www.googleapis.com/oauth2/v3/userinfo` using the `access_token` from Frontend `cookie`
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3. Google **response** to Backend with profile data
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4. Backend **response** to Frontend with profile data
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<br><br><br>
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# 1. Get Code
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1. Frontend **GET** to Google `https://accounts.google.com/o/oauth2` with callback url
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2. Google **302** to Backend `https://xorismesiti.gr/api/auth/callback` with authorization code
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### 1. Front **GET** to Google
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```sh
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GET https://accounts.google.com/o/oauth2/v2/auth?
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response_type=code& # This indicates you're using the "authorization code" flow.
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client_id=ABC34JHS9D& # Your Google API client ID created on the google API console.
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redirect_uri=https://xorismesiti.gr/api/auth/callback& # The URI Google will redirect to after the user consents.
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scope=email%20profile& # The permissions you're requesting (e.g., email, profile).
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state=xyz123 # A random string to protect against CSRF attacks.
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```
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### 2. Google **302** to Back
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```bash
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HTTP/1.1 302 Found
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Location: https://xorismesiti.gr/api/auth/callback?code=4/0AX4XfWgyVyz-uT8k7WiyLg0Q&state=xyz123
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Content-Type: text/html; charset=UTF-8
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Content-Length: 0
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```
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*Security: the state string should be validated upon receiving the response from Google, as it ensures that the response corresponds to the request.*
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<br><br><br>
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# 2. Exchange Code with Token
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1. Backend **POST** the `code` to Google `https://oauth2.googleapis.com/token`
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2. Google **response** to Backend with an `access_token` and a `refresh token`
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3. Backend **response** to Frontend with the `access_token` in a `cookie`
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### 1. Backend **POST** the `code` to Google
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```sh
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POST https://oauth2.googleapis.com/token
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Content-Type: application/x-www-form-urlencoded
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grant_type=authorization_code&
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code=AAAABCX4XfWgyVyziyLg0QHHHHH&
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client_id=ABC34JHS9D&
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client_secret=PASS1234&
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redirect_uri=https://xorismesiti.gr/callback
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```
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### 2. Google **response** to Backend
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```json
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{
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"access_token": "ya29.a0AfH6SMC8Op6zXZkHi2XITkDoOVzYXt3hTY6sny54UlWlxrnKlX5Xv78is7BEHekVX-VoA",
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"token_type": "Bearer",
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"expires_in": 3600,
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"refresh_token": "1//04d5XHqmn6Hdy3wTf5OYDP1SyBa74zEFURjddQ2A1cFw78PY13pQyWhlD2A6XhDQtKlrjAqU4kS3vGdMvckw",
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"scope": "email profile"
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}
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```
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### 3. Backend **response** to Frontend (for the initial request to Google)
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```json
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{
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"access_token": "ya29.a0AfH6SMC8Op6zXZkHi2XITkDoOVzYXt3hTY6sny54UlWlxrnKlX5Xv78is7BEHekVX-VoA",
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"token_type": "Bearer",
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"expires_in": 3600,
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}
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```
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<details>
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<summary>
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<h4>Backend code</h4>
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<br><br>
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<p>Implements the endpoint /auth/google/callback</p>
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<br>
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<ul>
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<li>Recieves authorization code from Google</li>
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<li>POST send the authorization code to https://oauth2.googleapis.com/token</li>
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<li>POST response the access & refresh tokens</li>
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<li>Respond the Fronend initial request with a cookie</li>
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</ul>
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</summary>
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```js
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// Backend callback URL: http://localhost:3000/auth/google/callback
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app.get('/auth/google/callback', async (req, res) => {
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const { code } = req.query; // Extract the code from the query string
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try {
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// Exchange the authorization code for access token and refresh token
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const response = await axios.post('https://oauth2.googleapis.com/token', null, {
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params: {
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code,
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client_id: clientId,
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client_secret: clientSecret,
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redirect_uri: redirectUri, // Same as in Step 1
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grant_type: 'authorization_code',
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},
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});
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const { access_token, refresh_token, expires_in } = response.data;
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// Store tokens in session or cookies
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res.cookie('access_token', access_token, { httpOnly: true, secure: true, maxAge: expires_in * 1000 });
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res.cookie('refresh_token', refresh_token, { httpOnly: true, secure: true });
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// Respond to frontend or redirect as needed
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res.send('Authentication successful! You can now use the app.');
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} catch (error) {
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console.error('Error exchanging code for tokens:', error);
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res.status(500).send('Error during authentication');
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}
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});
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```
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</details>
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<br><br><br>
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# 3. Use Token
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### 1. Frontend **GET** profile data from Backend
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```bash
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curl -X GET https://xorismesiti.gr/api/auth/profile \
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-H "Cookie: access_token=ya29.a0AfH6SMC8Op6zXZkHi2XITkDoOVzYXt3hTY6sny54UlWlxrnKlX5Xv78is7BEHekVX-VoA" \
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-H "Accept: application/json"
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```
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### 2. Backend **GET** profile data from Google
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```bash
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curl -X GET "https://www.googleapis.com/oauth2/v3/userinfo" \
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-H "Authorization: Bearer {access_token}" \
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-H "Accept: application/json"
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```
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### 3. Google **response** to Back with profile data
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```
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{
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"sub": "1234567890",
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"name": "John Doe",
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"given_name": "John",
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"family_name": "Doe",
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"profile": "https://plus.google.com/1234567890",
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"picture": "https://lh3.googleusercontent.com/a-/AOh14GgIXXl5JXzW0c1Szbl-e1Jch1vhl5rHhH65vlK6J5g5PqkGjj1O0p3t8bgVEOykQ6ykFSQ=s96",
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"email": "john.doe@example.com",
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"email_verified": true,
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"locale": "en"
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}
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```
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### 4. Backend **response** to Front with profile data
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```
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{
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"sub": "1234567890",
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"name": "John Doe",
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"picture": "https://lh3.googleusercontent.com/8bgVEOykQ6ykFSQ=s96",
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"email": "john.doe@example.com",
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}
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```
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### Frontend Code
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```js
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import React, { useState, useEffect } from 'react';
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import axios from 'axios';
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const App = () => {
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const [user, setUser] = useState(null);
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const [isAuthenticated, setIsAuthenticated] = useState(false);
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// Fetch user data from the backend's /profile endpoint
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const fetchUserData = async () => {
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try {
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const response = await axios.get('http://localhost:3000/profile', {
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withCredentials: true, // Important: Ensure cookies are sent with the request
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});
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setUser(response.data); // Set the user data from the response
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setIsAuthenticated(true);
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} catch (error) {
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console.error('Error fetching user profile:', error);
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}
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};
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useEffect(() => {
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// Check if the user is authenticated by checking the cookie
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if (document.cookie.includes('access_token')) {
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fetchUserData(); // Fetch user profile if the access token is available in cookies
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}
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}, []);
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return (
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<div className="App">
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<h1>Google OAuth2 with React</h1>
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{!isAuthenticated ? (
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<div>
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<p>Please log in with Google to access your profile:</p>
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<button onClick={() => window.location.href = 'http://localhost:3000/auth/google'}>
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Login with Google
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</button>
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</div>
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) : (
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<div>
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<h2>Welcome, {user?.name}</h2>
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<p>Email: {user?.email}</p>
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<img src={user?.picture} alt="Profile" />
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</div>
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)}
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</div>
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);
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};
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export default App;
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```
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-------------------------
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```bash
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GET https://xorismesiti.gr/api/user-profile
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Authorization: Bearer access-token-from-backend
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```
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```json
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{
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"sub": "1234567890",
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"name": "John Doe",
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"given_name": "John",
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"family_name": "Doe",
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"profile": "https://plus.google.com/1234567890",
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"picture": "https://lh3.googleusercontent.com/a-/AOh14GgIXXl5JXzW0c1Szbl-e1Jch1vhl5rHhH65vlK6J5g5PqkGjj1O0p3t8bgVEOykQ6ykFSQ=s96",
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"email": "john.doe@example.com",
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"email_verified": true,
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"locale": "en"
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}
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```
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```sh
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GET https://www.googleapis.com/oauth2/v3/userinfo
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Authorization: Bearer ya29.a0AfH6SMC8Op6zXZkHi2XITkDoOVzYXt3hTY6sny54UlWlxrnKlX5Xv78is7BEHekVX-VoA
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```
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```json
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{
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"sub": "1234567890",
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"name": "John Doe",
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"given_name": "John",
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"family_name": "Doe",
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"profile": "https://plus.google.com/1234567890",
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"picture": "https://lh3.googleusercontent.com/a-/AOh14GgIXXl5JXzW0c1Szbl-e1Jch1vhl5rHhH65vlK6J5g5PqkGjj1O0p3t8bgVEOykQ6ykFSQ=s96",
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"email": "john.doe@example.com",
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"email_verified": true,
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"locale": "en"
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}
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```
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```json
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{
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"access_token": "ya29.a0AfH6SMC8Op6zXZkHi2XITkDoOVzYXt3hTY6sny54UlWlxrnKlX5Xv78is7BEHekVX-VoA",
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"token_type": "Bearer",
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"expires_in": 3600
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}
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``` |