Add REST API for creating an account (#9572)

* Add REST API for creating an account

The method is available to apps with a token obtained via the client
credentials grant. It creates a user and account records, as well as
an access token for the app that initiated the request. The user is
unconfirmed, and an e-mail is sent as usual.

The method returns the access token, which the app should save for
later. The REST API is not available to users with unconfirmed
accounts, so the app must be smart to wait for the user to click a
link in their e-mail inbox.

The method is rate-limited by IP to 5 requests per 30 minutes.

* Redirect users back to app from confirmation if they were created with an app

* Add tests

* Return 403 on the method if registrations are not open

* Require agreement param to be true in the API when creating an account

2 files changed, 7 insertions, 3 deletions

diff --git a/app/views/user_mailer/confirmation_instructions.html.haml b/app/views/user_mailer/confirmation_instructions.html.haml
index 1f088a16f..f75f7529a 100644
--- a/app/views/user_mailer/confirmation_instructions.html.haml
+++ b/app/views/user_mailer/confirmation_instructions.html.haml
@@ -55,8 +55,12 @@
                             %tbody
                               %tr
                                 %td.button-primary
-                                  = link_to confirmation_url(@resource, confirmation_token: @token) do
-                                    %span= t 'devise.mailer.confirmation_instructions.action'
+                                  - if @resource.created_by_application
+                                    = link_to confirmation_url(@resource, confirmation_token: @token, redirect_to_app: 'true') do
+                                      %span= t 'devise.mailer.confirmation_instructions.action_with_app', app: @resource.created_by_application.name
+                                  - else
+                                    = link_to confirmation_url(@resource, confirmation_token: @token) do
+                                      %span= t 'devise.mailer.confirmation_instructions.action'
 
 %table.email-table{ cellspacing: 0, cellpadding: 0 }
   %tbody
diff --git a/app/views/user_mailer/confirmation_instructions.text.erb b/app/views/user_mailer/confirmation_instructions.text.erb
index e01eecb27..65b4626c6 100644
--- a/app/views/user_mailer/confirmation_instructions.text.erb
+++ b/app/views/user_mailer/confirmation_instructions.text.erb
@@ -4,7 +4,7 @@
 
 <%= t 'devise.mailer.confirmation_instructions.explanation', host: site_hostname %>
 
-=> <%= confirmation_url(@resource, confirmation_token: @token) %>
+=> <%= confirmation_url(@resource, confirmation_token: @token, redirect_to_app: @resource.created_by_application ? 'true' : nil) %>
 
 <%= strip_tags(t('devise.mailer.confirmation_instructions.extra_html', terms_path: about_more_url, policy_path: terms_url)) %>