## GoogleOAuth

- User clicks 'Login'.
- Direct to /auth/google
- Forward users's request to Google
- Ask user if they grant permission
- User grants permission
- Redirect with callback
- Callback gets code from URL
- Send request to google with 'code' included
- Google checks the code in the URL and returns details about the user
- Get the user details, create new record in database

### Passport
Pasport is used to handle authentication.
```
const passport = require('passport');
```
#
### Google Strategy
```passport-google-oauth20``` is added to passport as a strategy.
```
const GoogleStrategy = require('passport-google-oauth20').Strategy;

passport.use(
  new GoogleStrategy({
    clientID: keys.googleClientID,
    clientSecret: keys.googleClientSecret,
    callbackURL: '/auth/google/callback'
  }, (accessToken, refreshToken, profile) => {
    console.log(accessToken, profile);
  })
);
```
#
### Direct user to Google
'google' tells passport to use the GoogleStrategy for authentication

scope tells us what we want to be returned
```
app.get('/auth/google', passport.authenticate('google', {
    scope: ['profile', 'email']
})
```
#
### Handle callback from Google with response code.
Google Strategy sees the code in callback URL and use it to return a profile
```
app.get('/auth/google/callback', passport.authenticate('google'));
```
#
### Serialize and Deserialize user
Used to create the cookie and to check the cookie later on.
```
passport.serializeUser((user, done) => {
  done(null, user.id);
});

passport.deserializeUser((id, done) => {
  User.findById(id).then(user => {
    done(null, user);
  });
});
```
#
### Cookie Session
npm install --save ```cookie-session``` to add support for cookies.

Add cookieSession to serverfile.js

maxAge is the time the browser should save the cookie.

Keys is an array of keys that is used to controll that the cookie is right.
```
const cookieSession = require('cookie-session');

app.use(
  cookieSession({
    maxAge: 30 * 24 * 60 * 60 * 1000,
    keys: [keys.cookieKey]
  })
);

```
#

```
passport.initialize()
passport.session()
```
Initialize is a middle-ware that initialises Passport.

Session is another middleware that alters the request object and change the 'user' value that is currently the session id (from the client cookie) into the true deserialized user object.
#
### Logout
Call .logout() and then redirect to homepage.
```
app.get('/api/logout', (req, res) => {
  req.logout();
  res.redirect('/');
});


<li><a href="/api/logout">Logout</a></li>
```

### Redirect when logging in
Another callback after authenticate redirect user when logging in.
```
app.get(
  '/auth/google/callback',
  passport.authenticate('google'),
  (req, res) => {
    res.redirect('/serveys');
  }
);
  ```