wikis: force wiki names to follow same rules as tag names.

Don't allow wiki pages to have invalid names.

This incidentally means that you can't create wiki pages for pools. For
example, you can't create a wiki titled "pool:almost_heart-warming".
This is not a valid tag name, so it's not a valid wiki name either. This
was done in a handful of cases to translate Pixiv tags to Danbooru pools
(see: <https://danbooru.donmai.us/wiki_page_versions?search[title_like]=pool:*>)

Also fix it so that titles are normalized before validation, not before save.

app/models/wiki_page.rb

@@ -3,14 +3,13 @@ class WikiPage < ApplicationRecord
 
   META_WIKIS = ["list_of_", "tag_group:", "pool_group:", "howto:", "about:", "help:", "template:"]
 
-  before_save :normalize_title
-  before_save :normalize_other_names
+  before_validation :normalize_title
+  before_validation :normalize_other_names
   before_save :update_dtext_links, if: :dtext_links_changed?
   after_save :create_version
 
-  validates_uniqueness_of :title, :case_sensitive => false
-  validates_presence_of :title
-  validates_presence_of :body, :unless => -> { is_deleted? || other_names.present? }
+  validates :title, tag_name: true, presence: true, uniqueness: true, if: :title_changed?
+  validates :body, presence: true, unless: -> { is_deleted? || other_names.present? }
   validate :validate_rename
   validate :validate_other_names
 
@@ -149,8 +148,7 @@ class WikiPage < ApplicationRecord
   end
 
   def self.normalize_title(title)
-    return if title.blank?
-    title.downcase.delete_prefix("~").gsub(/[[:space:]]+/, "_").gsub(/__/, "_").gsub(/\A_|_\z/, "")
+    title.to_s.downcase.delete_prefix("~").gsub(/[[:space:]]+/, "_").gsub(/__/, "_").gsub(/\A_|_\z/, "")
   end
 
   def normalize_title

test/functional/wiki_pages_controller_test.rb

@@ -109,13 +109,6 @@ class WikiPagesControllerTest < ActionDispatch::IntegrationTest
         assert_response 404
       end
 
-      should "render for a negated tag" do
-        as(@user) { @wiki_page.update(title: "-aaa") }
-
-        get wiki_page_path(@wiki_page.id)
-        assert_redirected_to wiki_page_path(@wiki_page.title)
-      end
-
       should "work for a title containing dots" do
         as(@user) { create(:wiki_page, title: "...") }
 

test/unit/wiki_page_test.rb

@@ -78,6 +78,29 @@ class WikiPageTest < ActiveSupport::TestCase
       end
     end
 
+    context "during title validation" do
+      # these values are allowed because they're normalized first
+      should allow_value(" foo ").for(:title).on(:create)
+      should allow_value("~foo").for(:title).on(:create)
+      should allow_value("_foo").for(:title).on(:create)
+      should allow_value("foo_").for(:title).on(:create)
+      should allow_value("foo__bar").for(:title).on(:create)
+      should allow_value("FOO").for(:title).on(:create)
+      should allow_value("foo bar").for(:title).on(:create)
+
+      should_not allow_value("").for(:title).on(:create)
+      should_not allow_value("___").for(:title).on(:create)
+      should_not allow_value("-foo").for(:title).on(:create)
+      should_not allow_value("/foo").for(:title).on(:create)
+      should_not allow_value("foo*bar").for(:title).on(:create)
+      should_not allow_value("foo,bar").for(:title).on(:create)
+      should_not allow_value("foo\abar").for(:title).on(:create)
+      should_not allow_value("café").for(:title).on(:create)
+      should_not allow_value("東方").for(:title).on(:create)
+      should_not allow_value("FAV:blah").for(:title).on(:create)
+      should_not allow_value("X"*171).for(:title).on(:create)
+    end
+
     context "with other names" do
       should "not allow artist wikis to have other names" do
         tag = create(:artist_tag)