refactor how artist notes are updated

app/models/artist.rb

@@ -6,9 +6,10 @@ class Artist < ActiveRecord::Base
   after_save :create_version
   after_save :save_url_string
   after_save :categorize_tag
+  after_save :update_wiki
   validates_uniqueness_of :name
-  validate :name_is_valid
-  validate :wiki_is_empty, :on => :create
+  validate :validate_name
+  validate :validate_wiki, :on => :create
   belongs_to :creator, :class_name => "User"
   has_many :members, :class_name => "Artist", :foreign_key => "group_name", :primary_key => "name"
   has_many :urls, :dependent => :destroy, :class_name => "ArtistUrl"
@@ -16,8 +17,7 @@ class Artist < ActiveRecord::Base
   has_one :wiki_page, :foreign_key => "title", :primary_key => "name"
   has_one :tag_alias, :foreign_key => "antecedent_name", :primary_key => "name"
   has_one :tag, :foreign_key => "name", :primary_key => "name"
-  accepts_nested_attributes_for :wiki_page
-  attr_accessible :body, :name, :url_string, :other_names, :other_names_comma, :group_name, :wiki_page_attributes, :notes, :as => [:member, :gold, :builder, :platinum, :janitor, :moderator, :default, :admin]
+  attr_accessible :body, :notes, :name, :url_string, :other_names, :other_names_comma, :group_name, :notes, :as => [:member, :gold, :builder, :platinum, :janitor, :moderator, :default, :admin]
   attr_accessible :is_active, :as => [:builder, :janitor, :moderator, :default, :admin]
   attr_accessible :is_banned, :as => :admin
 
@@ -99,7 +99,7 @@ class Artist < ActiveRecord::Base
       end
     end
 
-    def name_is_valid
+    def validate_name
       if name =~ /^[-~]/
         errors[:name] << "cannot begin with - or ~"
         false
@@ -219,47 +219,61 @@ class Artist < ActiveRecord::Base
   end
 
   module NoteMethods
+    extend ActiveSupport::Concern
+
     def notes
-      if wiki_page
-        wiki_page.body
-      else
-        nil
+      @notes || wiki_page.try(:body)
+    end
+
+    def notes=(text)
+      if notes != text
+        notes_will_change!
+        @notes = text
       end
     end
 
-    def notes=(msg)
-      if name_changed? && name_was.present?
-        old_wiki_page = WikiPage.titled(name_was).first
-      end
-    
-      if wiki_page
-        if name_changed? && name_was.present?
-          wiki_page.body = wiki_page.body + "\n\n" + msg
-        else
-          wiki_page.body = msg
-        end
-        if wiki_page.body_changed?
-          wiki_page.save
-          @notes_changed = true
-        end
-      elsif old_wiki_page
-        old_wiki_page.title = name
-        old_wiki_page.body = msg
-        if old_wiki_page.body_changed? || old_wiki_page.title_changed?
-          old_wiki_page.save
-          @notes_changed = true
-        end
-      elsif msg.present?
-        self.wiki_page = WikiPage.new(:title => name, :body => msg)
-        @notes_changed = true
+    def reload(options = nil)
+      if instance_variable_defined?(:@notes)
+        remove_instance_variable(:@notes)
       end
+
+      super
     end
 
     def notes_changed?
-      !!@notes_changed
+      attribute_changed?("notes")
     end
 
-    def wiki_is_empty
+    def notes_will_change!
+      attribute_will_change!("notes")
+    end
+
+    def update_wiki
+      if persisted? && name_changed? && name_was.present? && WikiPage.titled(name_was).exists?
+        # we're renaming the artist, so rename the corresponding wiki page
+        old_page = WikiPage.titled(name_was).first
+
+        if wiki_page.present?
+          # a wiki page with the new name already exists, so update the content
+          wiki_page.update(body: "#{wiki_page.body}\n\n#{@notes}")
+        else
+          # a wiki page doesn't already exist for the new name, so rename the old one
+          old_page.update(title: name, body: @notes)
+        end
+      elsif wiki_page.nil?
+        # if there are any notes, we need to create a new wiki page
+        if @notes.present?
+          create_wiki_page(body: @notes, title: name)
+        end
+      elsif wiki_page.body != @notes || wiki_page.title != name
+        # if anything changed, we need to update the wiki page
+        wiki_page.body = @notes unless @notes.nil?
+        wiki_page.title = name
+        wiki_page.save
+      end
+    end
+
+    def validate_wiki
       if WikiPage.titled(name).exists?
         errors.add(:name, "conflicts with a wiki page")
         return false