Sync AuthUser and User names

Callbacks are handy for this!

app/models/auth_user.rb

@@ -8,7 +8,23 @@ class AuthUser < AuthRecord
   validates :name, presence: true, uniqueness: {case_sensitive: false},
     length: {maximum: 20}
   
-  after_create do
+  has_one :user, foreign_key: :remote_id, inverse_of: :auth_user
+  
+  # It's important to keep AuthUser and User in sync. When we create an AuthUser
+  # (e.g. through the registration process), we create a matching User, too. And
+  # when the AuthUser's name changes, we update User to match.
+  #
+  # TODO: Should we sync deletions too? We don't do deletions anywhere in app
+  # right now, so I'll hold off to avoid leaving dead code around.
+  after_create :create_user
+  after_update :sync_name_with_user, if: :saved_change_to_name?
+
+  def create_user
     User.create(name: name, auth_server_id: 1, remote_id: id)
   end
+
+  def sync_name_with_user
+    user.name = name
+    user.save!
+  end
 end

app/models/user.rb

@@ -3,6 +3,8 @@ class User < ApplicationRecord
 
   PreviewTopContributorsCount = 3
 
+  belongs_to :auth_user, foreign_key: :remote_id, inverse_of: :user
+
   has_many :closet_hangers
   has_many :closet_lists
   has_many :closeted_items, through: :closet_hangers, source: :item
@@ -22,6 +24,13 @@ class User < ApplicationRecord
 
   scope :top_contributors, -> { order('points DESC').where('points > 0') }
 
+  after_update :sync_name_with_auth_user, if: :saved_change_to_name?
+
+  def sync_name_with_auth_user
+    auth_user.name = name
+    auth_user.save!
+  end
+
   def admin?
     name == 'matchu' # you know that's right.
   end