[WIP] Fully implement "Sign in with GitHub"

[jankeromnes]

(Last salvaged commit from an old Janitor container. Exciting stuff!)

[jankeromnes]

This might help:

commit c14750daf21d604802a4064ae8d1a4f12f90e520
Author: Jan Keromnes <janx@linux.com>
Date:   Sun Oct 1 09:45:56 2017 +0000

    TEMP

diff --git a/app.js b/app.js
index 264f0ed..c55d626 100644
--- a/app.js
+++ b/app.js
@@ -163,22 +163,38 @@ boot.executeInParallel([
   // User login via GitHub.
   app.route(/^\/login\/github\/?$/, (data, match, end, query) => {
     const { req: request, res: response } = query;
-    const { user } = request;
-    if (!user) {
-      // Don't allow signing in only with GitHub just yet.
-      routes.notFoundPage(response, user);
-      return;
-    }
-
     github.authenticate(request, (error, accessToken, refreshToken) => {
+      const { user } = request;
       if (error) {
         log('[fail] github authenticate', error);
         routes.notFoundPage(response, user);
         return;
       }
 
-      users.refreshGitHubAccount(user, accessToken, refreshToken);
-      routes.redirect(response, '/settings/integrations/');
+      if (user) {
+        users.refreshGitHubAccount(user, accessToken, refreshToken, error => {
+          if (error) {
+            log('[fail] could not refresh github account', error);
+          }
+  
+          routes.redirect(response, '/settings/integrations/');
+        });
+        return;
+      }
+
+      // TODO multiple emails
+      github.getVerifiedEmails(accessToken, (error, verifiedEmails) => {
+        const users = db.get('users');
+        for (const verifiedEmail of verifiedEmails) {
+          if (users[verifiedEmail]) {
+            // TODO sign in
+          }
+        }
+
+        // Don't allow unregistered users to sign in with GitHub just yet.
+        // TODO "We don't have a Janitor account associated with the GitHub user that you used to sign in."
+        routes.notFoundPage(response, user);
+      });
     });
   });
 
diff --git a/lib/users.js b/lib/users.js
index 0154fa2..d4632ed 100644
--- a/lib/users.js
+++ b/lib/users.js
@@ -95,10 +95,10 @@ exports.resetSSHKeyPair = function (user) {
 };
 
 // Refresh a user's GitHub account details using an OAuth2 access token.
-exports.refreshGitHubAccount = function (user, accessToken, refreshToken) {
+exports.refreshGitHubAccount = function (user, accessToken, refreshToken, callback) {
   github.getUserProfile(accessToken, (error, profile) => {
     if (error) {
-      log('[fail] could not get github username', error);
+      callback(error);
       return;
     }
 
@@ -109,6 +109,7 @@ exports.refreshGitHubAccount = function (user, accessToken, refreshToken) {
     user.profile.name = user.profile.name || name;
 
     db.save();
+    callback();
 
     github.getSSHPublicKeys(username, (error, sshPublicKeys) => {
       if (error) {
@@ -290,6 +291,11 @@ function getOrCreateUser (email) {
     users[email] = user;
     db.save();
   }
+  
+  // Follow email aliases.
+  while (typeof user === 'string') {
+    user = users[user];
+  }
 
   // Temporary migration code: Previous users didn't have an SSH key pair.
   if (!user.keys.ssh) {