Add consumable invites (#5814)

* Add consumable invites

* Add UI for generating invite codes

* Add tests

* Display max uses and expiration in invites table, delete invite

* Remove unused column and redundant validator

- Default follows not used, probably bad idea
- InviteCodeValidator is redundant because RegistrationsController
  checks invite code validity

* Add admin setting to disable invites

* Add admin UI for invites, configurable role for invite creation

- Admin UI that lists everyone's invites, always available
- Admin setting min_invite_role to control who can invite people
- Non-admin invite UI only visible if users are allowed to

* Do not remove invites from database, expire them instantly

4 files changed, 95 insertions, 3 deletions

diff --git a/app/controllers/admin/invites_controller.rb b/app/controllers/admin/invites_controller.rb
new file mode 100644
index 000000000..f4207e3e2
--- /dev/null
+++ b/app/controllers/admin/invites_controller.rb
@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Admin
+  class InvitesController < BaseController
+    def index
+      authorize :invite, :index?
+
+      @invites = Invite.includes(user: :account).page(params[:page])
+      @invite  = Invite.new
+    end
+
+    def create
+      authorize :invite, :create?
+
+      @invite      = Invite.new(resource_params)
+      @invite.user = current_user
+
+      if @invite.save
+        redirect_to admin_invites_path
+      else
+        @invites = Invite.page(params[:page])
+        render :index
+      end
+    end
+
+    def destroy
+      @invite = Invite.find(params[:id])
+      authorize @invite, :destroy?
+      @invite.expire!
+      redirect_to admin_invites_path
+    end
+  end
+end
diff --git a/app/controllers/admin/settings_controller.rb b/app/controllers/admin/settings_controller.rb
index d9199b3d5..eed5fb6b5 100644
--- a/app/controllers/admin/settings_controller.rb
+++ b/app/controllers/admin/settings_controller.rb
@@ -16,6 +16,7 @@ module Admin
       show_staff_badge
       bootstrap_timeline_accounts
       thumbnail
+      min_invite_role
     ).freeze
 
     BOOLEAN_SETTINGS = %w(
diff --git a/app/controllers/auth/registrations_controller.rb b/app/controllers/auth/registrations_controller.rb
index 223db96ff..da0b6512f 100644
--- a/app/controllers/auth/registrations_controller.rb
+++ b/app/controllers/auth/registrations_controller.rb
@@ -16,13 +16,16 @@ class Auth::RegistrationsController < Devise::RegistrationsController
 
   def build_resource(hash = nil)
     super(hash)
-    resource.locale = I18n.locale
+
+    resource.locale      = I18n.locale
+    resource.invite_code = params[:invite_code] if resource.invite_code.blank?
+
     resource.build_account if resource.account.nil?
   end
 
   def configure_sign_up_params
     devise_parameter_sanitizer.permit(:sign_up) do |u|
-      u.permit({ account_attributes: [:username] }, :email, :password, :password_confirmation)
+      u.permit({ account_attributes: [:username] }, :email, :password, :password_confirmation, :invite_code)
     end
   end
 
@@ -35,7 +38,19 @@ class Auth::RegistrationsController < Devise::RegistrationsController
   end
 
   def check_enabled_registrations
-    redirect_to root_path if single_user_mode? || !Setting.open_registrations
+    redirect_to root_path if single_user_mode? || !allowed_registrations?
+  end
+
+  def allowed_registrations?
+    Setting.open_registrations || (invite_code.present? && Invite.find_by(code: invite_code)&.valid_for_use?)
+  end
+
+  def invite_code
+    if params[:user]
+      params[:user][:invite_code]
+    else
+      params[:invite_code]
+    end
   end
 
   private
diff --git a/app/controllers/invites_controller.rb b/app/controllers/invites_controller.rb
new file mode 100644
index 000000000..38d6c8d73
--- /dev/null
+++ b/app/controllers/invites_controller.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class InvitesController < ApplicationController
+  include Authorization
+
+  layout 'admin'
+
+  before_action :authenticate_user!
+
+  def index
+    authorize :invite, :create?
+
+    @invites = Invite.where(user: current_user)
+    @invite  = Invite.new(expires_in: 1.day.to_i)
+  end
+
+  def create
+    authorize :invite, :create?
+
+    @invite      = Invite.new(resource_params)
+    @invite.user = current_user
+
+    if @invite.save
+      redirect_to invites_path
+    else
+      @invites = Invite.where(user: current_user)
+      render :index
+    end
+  end
+
+  def destroy
+    @invite = Invite.where(user: current_user).find(params[:id])
+    authorize @invite, :destroy?
+    @invite.expire!
+    redirect_to invites_path
+  end
+
+  private
+
+  def resource_params
+    params.require(:invite).permit(:max_uses, :expires_in)
+  end
+end