wiki pages, artists: fix normalization of other names.

Fix wiki pages and artists to normalize other names more consistently
and correctly.

For wiki pages, we strip leading / trailing / repeated underscores to
fix user typos, and we normalize to NFKC form to make search more consistent.

For artists, we allow leading / trailing / repeated underscores because
some artist names have these, and we normalize to NFC form because some
artists have weird names that would be lost by NFKC form. This does make
search less consistent.

app/models/artist.rb

@@ -3,11 +3,13 @@ class Artist < ApplicationRecord
   class RevertError < StandardError; end
 
   attr_accessor :url_string_changed
-  array_attribute :other_names
+
   deletable
 
-  before_validation :normalize_name
-  before_validation :normalize_other_names
+  normalize :name, :normalize_name
+  normalize :other_names, :normalize_other_names
+  array_attribute :other_names # XXX must come after `normalize :other_names`
+
   validate :validate_tag_category
   validates :name, tag_name: true, uniqueness: true
   before_save :update_tag_category
@@ -55,27 +57,26 @@ class Artist < ApplicationRecord
     end
   end
 
-  module NameMethods
-    extend ActiveSupport::Concern
-
-    module ClassMethods
+  concerning :NameMethods do
+    class_methods do
       def normalize_name(name)
         name.to_s.mb_chars.downcase.strip.gsub(/ /, '_').to_s
       end
-    end
 
-    def normalize_name
-      self.name = Artist.normalize_name(name)
+      def normalize_other_names(other_names)
+        other_names.map { |name| normalize_other_name(name) }.uniq.reject(&:blank?)
+      end
+
+      # XXX Differences from wiki page other names: allow uppercase, use NFC
+      # instead of NFKC, and allow repeated, leading, and trailing underscores.
+      def normalize_other_name(other_name)
+        other_name.to_s.unicode_normalize(:nfc).normalize_whitespace.squish.tr(" ", "_")
+      end
     end
 
     def pretty_name
       name.tr("_", " ")
     end
-
-    def normalize_other_names
-      self.other_names = other_names.map { |x| Artist.normalize_name(x) }.uniq
-      self.other_names -= [name]
-    end
   end
 
   module VersionMethods
@@ -145,8 +146,6 @@ class Artist < ApplicationRecord
         artist = Artist.new(params)
       end
 
-      artist.normalize_name
-      artist.normalize_other_names
       artist
     end
   end
@@ -284,7 +283,6 @@ class Artist < ApplicationRecord
   end
 
   include UrlMethods
-  include NameMethods
   include VersionMethods
   extend FactoryMethods
   include TagMethods

app/models/wiki_page.rb

@@ -3,12 +3,12 @@ class WikiPage < ApplicationRecord
 
   META_WIKIS = ["list_of_", "tag_group:", "pool_group:", "howto:", "about:", "help:", "template:"]
 
-  before_validation :normalize_other_names
   before_save :update_dtext_links, if: :dtext_links_changed?
   after_save :create_version
 
   normalize :title, :normalize_title
   normalize :body, :normalize_text
+  normalize :other_names, :normalize_other_names
 
   validates :title, tag_name: true, presence: true, uniqueness: true, if: :title_changed?
   validates :body, presence: true, unless: -> { is_deleted? || other_names.present? }
@@ -153,12 +153,12 @@ class WikiPage < ApplicationRecord
     title.to_s.downcase.delete_prefix("~").gsub(/[[:space:]]+/, "_").squeeze("_").gsub(/\A_|_\z/, "")
   end
 
-  def normalize_other_names
-    self.other_names = other_names.map { |name| WikiPage.normalize_other_name(name) }.uniq
+  def self.normalize_other_names(other_names)
+    other_names.map { |name| normalize_other_name(name) }.uniq.reject(&:blank?)
   end
 
   def self.normalize_other_name(name)
-    name.unicode_normalize(:nfkc).gsub(/[[:space:]]+/, " ").strip.tr(" ", "_")
+    name.to_s.unicode_normalize(:nfkc).normalize_whitespace.gsub(/[[:space:]]+/, "_").squeeze("_").gsub(/\A_|_\z/, "")
   end
 
   def category_name