Add email invites to Phabricator (logic only)

Summary:
Ref T7152. This builds the core of email invites and implements all the hard logic for them, covering it with a pile of tests.

There's no UI to create these yet, so users can't actually get invites (and administrators can't send them).

This stuff is a complicated mess because there are so many interactions between accounts, email addresses, email verification, email primary-ness, and user verification. However, I think I got it right and got test coverage everwhere.

The degree to which this is exception-driven is a little icky, but I think it's a reasonable way to get the testability we want while still making it hard for callers to get the flow wrong. In particular, I expect there to be at least two callers (one invite flow in the upstream, and one derived invite flow in Instances) so I believe there is merit in burying as much of this logic inside the Engine as is reasonably possible.

Test Plan: Unit tests only.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7152

Differential Revision: https://secure.phabricator.com/D11723

src/applications/auth/controller/PhabricatorAuthInviteController.php

@@ -0,0 +1,58 @@
+<?php
+
+final class PhabricatorAuthInviteController
+  extends PhabricatorAuthController {
+
+  public function shouldRequireLogin() {
+    return false;
+  }
+
+  public function handleRequest(AphrontRequest $request) {
+    $viewer = $this->getViewer();
+
+    $engine = id(new PhabricatorAuthInviteEngine())
+      ->setViewer($viewer);
+
+    if ($request->isFormPost()) {
+      $engine->setUserHasConfirmedVerify(true);
+    }
+
+    try {
+      $invite = $engine->processInviteCode($request->getURIData('code'));
+    } catch (PhabricatorAuthInviteDialogException $ex) {
+      $response = $this->newDialog()
+        ->setTitle($ex->getTitle())
+        ->appendParagraph($ex->getBody());
+
+      $submit_text = $ex->getSubmitButtonText();
+      if ($submit_text) {
+        $response->addSubmitButton($submit_text);
+      }
+
+      $submit_uri = $ex->getSubmitButtonURI();
+      if ($submit_uri) {
+        $response->setSubmitURI($submit_uri);
+      }
+
+      $cancel_uri = $ex->getCancelButtonURI();
+      $cancel_text = $ex->getCancelButtonText();
+      if ($cancel_uri && $cancel_text) {
+        $response->addCancelButton($cancel_uri, $cancel_text);
+      } else if ($cancel_uri) {
+        $response->addCancelButton($cancel_uri);
+      }
+
+      return $response;
+    } catch (PhabricatorAuthInviteRegisteredException $ex) {
+      // We're all set on processing this invite, just send the user home.
+      return id(new AphrontRedirectResponse())->setURI('/');
+    }
+
+
+    // TODO: This invite is good, but we need to drive the user through
+    // registration.
+    throw new Exception(pht('TODO: Build invite/registration workflow.'));
+  }
+
+
+}