Merge pull request keystonejs#935 from gautamsi/gautamsi/improve-twit…

…ter-login

improve twitter login from keystonejs#164 code.

test-projects/twitter-login/twitter.js

@@ -1,5 +1,5 @@
 const TwitterAuthStrategy = require('@keystone-alpha/keystone/auth/Twitter');
-const { startAuthedSession } = require('@keystone-alpha/session');
+const { startAuthedSession, endAuthedSession } = require('@keystone-alpha/session');
 const { appURL, twitterAppKey, twitterAppSecret } = require('./config');
 
 exports.configureTwitterAuth = function(keystone, server) {
@@ -37,29 +37,58 @@ exports.configureTwitterAuth = function(keystone, server) {
     });
   });
 
+  server.app.get('/api/signout', async (req, res, next) => {
+    try {
+      await endAuthedSession(req);
+      res.json({
+        success: true,
+      });
+    } catch (e) {
+      next(e);
+    }
+  });
+
   // Twitter will redirect the user to this URL after approval.
   server.app.get(
     '/auth/twitter/callback',
     twitterAuth.authenticateMiddleware({
       async verified(item, { list }, req, res) {
+        // You could try and find user by email address here to match users
+        // if you get the email data back from Twitter, then refer to
+        // connectItem, for example:
+        // await keystone.auth.User.twitter.connectItem(req, { item });
+        // ...
+
+        // If we don't have a matching user in our system, force redirect to
+        // the create step
         if (!item) {
-          return res.redirect('/auth/twitter/details');
+          return res.redirect('/auth/twitter/create');
         }
+
+        // Otheriwse create a session based on the user we have already
         await startAuthedSession(req, { item, list });
+        // Redirect on sign in
         res.redirect('/api/session');
       },
       failedVerification(error, req, res) {
-        console.log('🤔 Failed to verify Twitter login creds');
+        console.log('Failed to verify Twitter login creds');
         res.redirect('/');
       },
     })
   );
 
-  // Sample page to collect a name, submits to the completion step
-  server.app.get('/auth/twitter/details', (req, res) => {
+  // Sample page to collect a name, submits to the completion step which will
+  // create a user
+  server.app.get('/auth/twitter/create', (req, res) => {
+    // Redirect if we're already signed in
     if (req.user) {
       return res.redirect('/api/session');
     }
+    // If we don't have a keystoneTwitterSessionId at this point, the form
+    // submission will fail, so fail out to the first step
+    if (!req.session.keystoneTwitterSessionId) {
+      return res.redirect('/auth/twitter');
+    }
 
     res.send(`
         <form action="/auth/twitter/complete" method="post">
@@ -74,10 +103,12 @@ exports.configureTwitterAuth = function(keystone, server) {
     '/auth/twitter/complete',
     server.express.urlencoded({ extended: true }),
     async (req, res, next) => {
+      // Redirect if we're already signed in
       if (req.user) {
         return res.redirect('/api/session');
       }
 
+      // Create a new User
       try {
         const list = keystone.getListByKey('User');